Pregnancy
Content
Stages of pregnancy
Your body will go through a number of changes during pregnancy and as your baby develops.
These can affect you in different ways.
How a baby develops during pregnancy
Your body goes through a lot of changes in pregnancy
Details
Conception
Conception means getting pregnant. An egg is released from one of your ovaries around
14 days before your period begins. This is called ovulation. This usually happens in the
middle of a 28-day menstrual cycle. However, it can vary between women and your cycle
may be longer or shorter than this.
After you have sex, this egg can be met by sperm from your partner in your fallopian
tube. One of the millions of sperm that your partner produces may fertilise the egg.
Sperm can survive in your fallopian tubes for up to seven days. Therefore, you don't need
to have sex at the exact time of ovulation to get pregnant.
Once fertilised, the egg will continue to travel along your fallopian tube towards your
womb (uterus) where it will bury itself in the lining. This process is called implantation.
Conception describes the process that starts with fertilisation and ends at implantation,
and this takes around seven days. The fertilised egg is growing all the time and is now
called an embryo.
Usually your womb loses its lining every month when you have your period. When you
become pregnant, this stops happening. You won’t have any periods while you’re
pregnant and missing a period is one of the early signs of pregnancy. However, some
women get some light bleeding at the time when the egg implants in the womb.
Pregnancy tests
You can buy pregnancy tests at pharmacies and supermarkets. Pregnancy tests work by
detecting a pregnancy hormone called beta-human chorionic gonadotrophin (hCG),
which will be in your urine if you're pregnant. Most types of pregnancy test can detect if
you’re pregnant from the first day of your first missed period. Some types can give a
result sooner than this. If the result of the test is positive, it indicates that you’re pregnant.
A pregnancy usually lasts for 37 to 42 weeks – the average is 40 weeks. This is calculated
from the first day of your last period and is often broken down into thirds, called
trimesters.
First trimester (one to 12 weeks)
Physical effects of pregnancy on you
Your body goes through a lot of hormonal changes in early pregnancy. This can lead to a
number of physical effects on you.
As well as missing your first period, you may notice that your breasts feel tender. Your
nipples and the area around them (the areola) may become darker too. You may find you
need to go to the toilet more often too, and you can feel very tired during your first
trimester.
Morning sickness
A common symptom in your first trimester is feeling sick and perhaps also vomiting.
This is known as ‘morning sickness’, but it can happen at any time of the day. The exact
reasons why you may get morning sickness aren't fully understood at present. However, it
may be because of the high levels of hormones that your body produces while you're
pregnant.
It may help to:
o eat little and often – you might find blander foods easier to eat
o get plenty of rest
o drink enough fluids
o stay away from smells and tastes that make you feel sick
o take a ginger supplement or drink ginger ale or tea
Morning sickness can make you feel very unwell but it’s important to remember that your
baby is unlikely to be affected by it. However, if you find you can’t keep any food or
fluids down, see your GP or midwife for advice. This is because you may become very
dehydrated, which can lead to complications.
Digestion problems
You may get constipated when you’re pregnant because pregnancy hormones relax and
slow the muscles of your digestive system and bowels. You can help to prevent
constipation by eating plenty of fibre-rich foods, such as green, leafy vegetables and fruit.
Also, make sure you drink enough fluids every day. The relaxation of the muscles in your
digestive system can also increase heartburn. Fatty foods and caffeine can make this
worse, so try not to have these.
Folic acid
It's important to take folic acid, both before you become pregnant (if possible) and until
at least week 12 of your pregnancy. Take 400 micrograms (µg) a day. Folic acid is
important for the development of your baby’s brain and spinal cord. It can prevent serious
problems, such as spina bifida.
If you have a health condition, such as diabetes, you may need to take a higher dose of
folic acid (up to 5000µg a day). Ask your GP or midwife what dose you need to take.
Smoking and alcohol
If you smoke, quitting will protect your baby from a number of health problems that can
occur during your pregnancy. It will also help your baby after he or she is born. This is
because smoking can affect your baby's chance of getting health conditions such as
asthma and colic. Your healthcare team will direct you to sources of support to help you
stop smoking.
The National Institute for Health and Care Excellence (NICE) recommends that you
don’t have any alcohol during the first three months of your pregnancy. This is because
it's linked to a number of developmental problems in babies. If you choose to drink
alcohol while you’re pregnant, limit yourself to one to two units, once or twice a week.
Your baby
During the first 12 weeks of your pregnancy, your baby will begin life as a tiny ball of
cells and develop quickly into an embryo.
By week 10, all your baby’s organs, such as its heart and lungs, are present, even if they
are not yet fully formed. Your baby is now known as a fetus. Your placenta is fully
formed. This structure develops on your womb and is linked to your baby by the
umbilical cord. Through this, nutrients are transferred from your blood into your baby. In
return, all the waste products from your baby are transferred back into your circulation,
so that you can get rid of them.
By week 12, your baby may be almost 8cm long. Their eyes are formed but tightly shut,
and their ears are still forming. Their brain is growing most rapidly, which means that
your baby’s head is much larger than their body.
Second trimester (13 to 27 weeks)
Physical effects of pregnancy on you
Your pregnancy will start to show during the second trimester – exactly when this
happens varies between women.
As your abdomen and breasts grow, you may get stretch marks. These are harmless and
will usually fade after your baby is born. You can try different moisturisers and lotions to
prevent stretch marks but none have been proven to work.
If you were vomiting or felt sick in your first trimester, this will usually get better by the
time you're 16 weeks pregnant. However, you may get backache and pain in your pelvis
because pregnancy hormones cause your ligaments and tendons to relax. This can cause
changes to your posture as your baby grows.
You may first feel your baby move around when you're 18 to 20 weeks pregnant.
However, this can vary – it can be a few weeks earlier if it's not your first pregnancy. The
movements will become much more vigorous and obvious as your baby gets bigger and
stronger.
If you haven’t felt your baby move by the time you're 24 weeks pregnant, contact your
midwife. He or she will arrange for you to have an ultrasound to check all is well with
your baby.
Your baby
In the second trimester, your baby's organs mature and their skeleton starts to harden.
Your baby will have bowel movements and their kidneys also begin to work and pass
small amounts of urine.
By 20 weeks, your baby is able to hear and is covered in fine hair called lanugo. If you
have a scan at this stage, it's often possible to find out whether your baby is a boy or a
girl.
By the end of the second trimester, your baby has a chance of surviving if he or she is
born prematurely. However, your baby would need intensive care.
Also by the end of the second trimester, your baby grows fingernails, and teeth may start
to grow under their gums.
Third trimester (28 to 40 weeks)
Physical effects of pregnancy on you
You may find the extra weight you’re carrying makes you tired, and you may get breathless as
your expanding womb reduces the space for your lungs. Your baby's head may press on your
bladder, so you might need to go to the toilet more often too.
You may have trouble finding a comfortable position to sleep in. This is because your baby's
head may drop down into your pelvis (engage) ready for delivery. This is usually towards the end
of your pregnancy, from around 36 weeks onwards. You might find it helps to put pillows
between your knees and to support your abdomen when you lie on your side.
Braxton-Hicks contractions – practice contractions – can start in the second trimester, but are
much more common in the third. These can be mistaken for labour, but the difference is that real
labour contractions are regular and usually cause some pain. Most women only get one or two
Braxton-Hicks contractions every hour and they fade away rather than getting stronger over time.
Your baby
Your baby's lungs mature throughout the third trimester. Your baby makes breathing movements,
even though their lungs don't work properly until birth. Their eyes can also open and close by
this time. Your baby will kick and stretch and respond to sound.
Your baby will be developing fat stores and it’s likely that they will turn into a head-down
position in preparation for birth.
Weight gain in pregnancy
You will put on weight during your pregnancy – the exact amount varies between women. Your
midwife will weigh you at your first appointment and also measure your height. He or she will
use these measurements to work out your body mass index (BMI). Unless you’re very over- or
underweight, your midwife probably won't weigh you again as it isn't usually necessary.
However, it's possible you might need to be weighed later on.
If you're concerned about your weight gain, talk to your midwife or GP. He or she will be able to
tell you whether it’s too much or too little.
The weight you gain during pregnancy doesn’t mean that you’re getting fat. The extra weight is
made up of:
your developing baby, placenta and amniotic fluid
the growth of your womb and breasts
the increased blood in your circulation
water retention
essential fat stores
How your baby develops in the womb
Click to open full-size image (153 KB)
FAQs
Can I fly when I am pregnant?
Answer
If your pregnancy hasn’t caused any complications to your health, there is no evidence that
flying is unsafe for you or your baby. However, there are recommendations for when it may be
best to stop travelling by plane. Airlines also have their own guidelines and rules for taking
pregnant passengers.
Explanation
If you choose to fly after you're 28 weeks pregnant, your airline will ask you to provide a letter
from your GP or midwife. This will need to confirm your due date and that he or she doesn’t
think you’re at an increased risk of complications by flying. After 37 weeks, if you’re pregnant
with one baby, there is a much higher chance that you will go into labour. This is because most
babies are born within two weeks of either side of their due date. If you’re pregnant with more
than one baby, this chance is higher from week 34 because twins (or more) often have shorter
pregnancies.
Some airlines won’t let pregnant women fly from 37 weeks, while others have an earlier cut-off
date.
Check with the airline before you book tickets. It may be more difficult to get travel insurance
after a certain point in your pregnancy too.
If you have any complications of pregnancy, or other existing health conditions, discuss with
your GP or midwife how flying could affect you. If you’re planning a long-haul flight, your risk
of deep vein thrombosis (DVT) may be higher when you’re pregnant. Make sure you drink
enough fluids and flex your ankles to encourage the flow of blood.
Flying hasn’t been shown to increase your chance of premature labour. However, if you were to
go into labour while on a plane, you’re likely to be far away from medical help. Also consider
the risk of infection and availability of health facilities at your destination in case problems
develop while you’re away.
Can my unborn child hear me?
Answer
Towards the end of your second trimester (13 to 27 weeks), your baby can hear a variety of
sounds from inside and outside your body. These sounds can include your voice and music.
Explanation
From week 16, your baby’s ears are fully formed and will begin transmitting sounds to your
baby. By week 21, your baby will become familiar with the sound of your heart beating and your
stomach rumbling. Your voice will also reach your baby in your womb and he or she will begin
to recognise you speaking. Your baby may also react to noises. Some people like to play music
for their baby to hear when they’re pregnant.
Is it safe to exercise during pregnancy?
Answer
Exercising when you’re pregnant can be beneficial to you and your unborn baby. However, some
activities aren’t suitable when you’re pregnant so you may need to adapt your usual routine as
your pregnancy progresses.
Explanation
There has been a lot of research to study the benefits of continuing or beginning regular exercise
during pregnancy. If you keep up exercise when you’re pregnant, you’re more likely to:
sleep better
have more energy
have better mental health and wellbeing
improve your posture
have less swollen ankles and hands
get fewer varicose veins
If you have developed diabetes during your pregnancy (gestational diabetes), exercise may help
to treat it. It may also help to prevent the condition from developing in the first place. This is
because exercising can help you to control your blood sugar levels better.
You need to take some precautions when choosing what type of exercise to do. Contact sports
aren’t suitable when you’re pregnant because of the risk of injury to your baby. Contact sports
include anything that carries a risk of you being hit in the abdomen, such as judo, squash or
hockey.
Activities that increase your risk of falling, such as horse riding, skiing, gymnastics and cycling,
are also not recommended. When you’re pregnant, you shouldn’t scuba dive, no matter what
your skill level is. This is because your baby can’t be protected against the effects of problems,
such as decompression sickness. Exercising at high altitudes can reduce blood flow to your baby
too.
The hormones you produce when you're pregnant can make your joints weaker. Therefore, it's a
good idea to warm up before you exercise and cool down afterwards.
Don’t do any exercise that involves you lying flat on your back after week 16 of your pregnancy.
This is because your womb can press on the large veins in your abdomen and may disrupt blood
flow to your baby. You may find you get hotter during exercise than you did when you weren’t
pregnant. Make sure you drink enough fluids and don’t exercise in hot or humid conditions.
If you feel any unusual symptoms during exercise, such as dizziness or pain, it's best to stop. See
your GP or midwife immediately afterwards.
My baby is in the breech position. What does this mean?
Answer
The breech position means that, inside your womb, your baby's bottom or feet are pointing down
towards your cervix and vagina. The majority of babies move their head downwards before they
are born. This is the natural position that makes birth more straightforward.
Explanation
By the time babies are ready to be born, only around three in 100 will still be in the breech
position. All the rest will have turned in the womb to be head downwards at some point before
the mother goes into labour.
When you go to your later antenatal appointments, your GP or midwife will check the position of
your baby. If your baby is breech at 36 weeks, he or she may refer you to an obstetrician (a
doctor who specialises in pregnancy and childbirth).
Your doctor will discuss a procedure to try to turn your baby so that they are head down before
birth. In this procedure, your midwife or doctor will place their hands on your abdomen and try
to move your baby inside your womb. He or she will try to turn your baby to do either a forward
or backward somersault. This is called external cephalic version and you will go into hospital to
have it done. An external cephalic version can feel uncomfortable at times – be sure to ask your
doctor to stop if it's painful.
If your baby remains breech, even after an external cephalic version, your doctor will talk to you
about your options for the birth. Depending on your individual circumstances you may choose to
have either a vaginal breech birth or a caesarean. Your doctor will help you to decide the best
option for you.
What will it feel like when my baby kicks? Will it hurt?
Answer
At first, your baby's movements can feel like 'flutters' in your lower abdomen (tummy). Later on,
as he or she grows and develops, you may feel your baby kick, swish or roll.
Explanation
From around week 18, you may begin to feel slight movements from your baby. If you have had
a baby before, you may notice the movements earlier than this because you recognise the
sensation.
As your baby continues to grow and get stronger, you will feel more definite and vigorous
kicking and prodding. As the space inside your abdomen gets more cramped for your baby, you
may be more affected by their movements. For example, your baby can press on your bladder or
keep you awake at night.
Some babies are more active than others but it's important to recognise your own baby’s pattern
of activity. If you notice any sudden change in the pattern of your baby's movements, contact
your GP or midwife. He or she can check that all is well.
When does my baby’s heart start beating during pregnancy?
Answer
The cells that make up your baby’s heart will start making beating movements from very early in
their development. By the end of your first month of pregnancy, your baby's heart will begin to
beat properly. Like all your baby’s organs, the heart is a complex structure that will continue to
develop and grow with your baby throughout your pregnancy. When you’re about six weeks
pregnant, your baby's heart will be pumping blood around its body and out along the umbilical
cord to the placenta.
Explanation
By week 11 of your pregnancy, all your baby’s organs will be present in various stages of
development. Gradually, each organ takes on its complete form, grows larger and begins to carry
out its proper function. By the time your baby is born, he or she can survive outside your womb.
When you're around 12 weeks pregnant you will have your first ultrasound scan. A sonographer
(a person specially trained to carry out ultrasound) will be able to detect your baby’s heartbeat
and listen to it using ultrasound. When you have your 20-week scan, your baby’s beating heart
will be visible. Your sonographer will check everything is working as it should.
Later in your pregnancy, your GP or midwife will be able to hear your baby’s heartbeat with a
stethoscope.
During pregnancy, labour and birth, your antenatal team can monitor your baby’s heart using a
range of other medical techniques. This can help diagnose your baby’s health and can also help if
you need to make decisions about when and where you give birth.
Resources
Further information
National
Childbirth
0300
Trust
(NCT)
330
0700
www.nct.org.uk
Royal
College
of
Obstetricians
and
Gynaecologists
cycle
sheet.
Womenshealth.gov.
www.rcog.org.uk
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and
the
menstrual
fact
www.womenshealth.gov, published 16 July 2012
Planning a pregnancy. Family Planning Association. www.fpa.org.uk, accessed 8 January
2014
Common
pregnancy
complaints
and
www.emedicine.medscape.com, published 5 June 2012
questions.
Medscape.
How your baby grows during pregnancy. American College of Obstetricians and
Gynecologists. www.acog.org, published August 2011
Huancahuari N. Emergencies in early pregnancy. Emerg Med Clin North Am 2012;
30(4):837–47. doi:10.1016/j.emc.2012.08.005.
Am I pregnant? Terrence Higgins Trust. www.tht.org.uk, published 1 June 2012
Antenatal care routine care for the healthy pregnant woman. National Institute for Health
and Care Excellence (NICE), March 2008. www.nice.org.uk
Physiological changes in pregnancy. PatientPlus. www.patient.co.uk/patientplus.asp,
published 25 January 2013
Matthews A, Dowswell T, Haas DM, et al. Interventions for nausea and vomiting in early
pregnancy.
Cochrane
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Systematic
Reviews
2010,
Issue
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doi:10.1002/14651858.CD007575.pub2
Morning sickness. American College of Obstetricians and Gynecologists. www.acog.org,
published October 2012
Nausea and vomiting in pregnancy – including hyperemesis gravidarum. PatientPlus.
www.patient.co.uk/patientplus.asp, published 12 December 2012
Common problems of pregnancy. PatientPlus. www.patient.co.uk/patientplus.asp,
published 10 July 2013
Pre-pregnancy counselling. PatientPlus. www.patient.co.uk/patientplus.asp, published 28
September 2013
Tobacco, alcohol, drugs, and pregnancy. American College of Obstetricians and
Gynecologists. www.acog.org, published December 2013
Stages of pregnancy. Womenshealth.gov. www.womenshealth.gov, published 27
September 2010
Your baby’s movements in pregnancy. Royal College of Obstetricians and
Gynaecologists. www.rcog.org.uk, published August 2012
Extremely low birth weight infant. Medscape. www.emedicine.medscape.com, published
2 October 2012
The last 3 months – the third trimester. Women's and Children's Health Network.
www.cyh.com, published 28 October 2013
Normal labor and delivery. Medscape. www.emedicine.medscape.com, published 1
October 2013
If your baby is in breech. American College of Obstetricians and Gynecologists.
www.acog.org, published August 2011
A breech baby at the end of pregnancy. Royal College of Obstetricians and
Gynaecologists. www.rcog.org.uk, published February 2008
Turning a breech baby in the womb (external cephalic version). Royal College of
Obstetricians and Gynaecologists. www.rcog.org.uk, published February 2008
Reduced fetal movements. Royal College of Obstetricians and Gynaecologists.
www.rcog.org.uk, published February 2011
Exercise during pregnancy. American College of Obstetricians and Gynecologists.
www.acog.org, published August 2011
Staying healthy and safe. Womenshealth.gov. www.womenshealth.gov, published 27
September 2010
Gestational
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Royal
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Obstetricians
and
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www.rcog.org.uk, published March 2013
Recreational exercise and pregnancy: information for you. Royal College of Obstetricians
and Gynaecologists. www.rcog.org.uk, published September 2006
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2014
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www.cyh.com, published 28 October 2013
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www.rcog.org.uk, published January 2011
Having twins. American College of Obstetricians and Gynecologists. www.acog.org,
published June 2012
Travel-related deep vein thrombosis. National Travel Health Network and Centre.
www.nathnac.org, published November 2011
Your body will go through a number of changes during pregnancy and as your baby develops.
These can affect you in different ways.
How a baby develops during pregnancy
Your body goes through a lot of changes in pregnancy
Details
Conception
Conception means getting pregnant. An egg is released from one of your ovaries around
14 days before your period begins. This is called ovulation. This usually happens in the
middle of a 28-day menstrual cycle. However, it can vary between women and your cycle
may be longer or shorter than this.
After you have sex, this egg can be met by sperm from your partner in your fallopian
tube. One of the millions of sperm that your partner produces may fertilise the egg.
Sperm can survive in your fallopian tubes for up to seven days. Therefore, you don't need
to have sex at the exact time of ovulation to get pregnant.
Once fertilised, the egg will continue to travel along your fallopian tube towards your
womb (uterus) where it will bury itself in the lining. This process is called implantation.
Conception describes the process that starts with fertilisation and ends at implantation,
and this takes around seven days. The fertilised egg is growing all the time and is now
called an embryo.
Usually your womb loses its lining every month when you have your period. When you
become pregnant, this stops happening. You won’t have any periods while you’re
pregnant and missing a period is one of the early signs of pregnancy. However, some
women get some light bleeding at the time when the egg implants in the womb.
Pregnancy tests
You can buy pregnancy tests at pharmacies and supermarkets. Pregnancy tests work by
detecting a pregnancy hormone called beta-human chorionic gonadotrophin (hCG),
which will be in your urine if you're pregnant. Most types of pregnancy test can detect if
you’re pregnant from the first day of your first missed period. Some types can give a
result sooner than this. If the result of the test is positive, it indicates that you’re pregnant.
A pregnancy usually lasts for 37 to 42 weeks – the average is 40 weeks. This is calculated
from the first day of your last period and is often broken down into thirds, called
trimesters.
First trimester (one to 12 weeks)
Physical effects of pregnancy on you
Your body goes through a lot of hormonal changes in early pregnancy. This can lead to a
number of physical effects on you.
As well as missing your first period, you may notice that your breasts feel tender. Your
nipples and the area around them (the areola) may become darker too. You may find you
need to go to the toilet more often too, and you can feel very tired during your first
trimester.
Morning sickness
A common symptom in your first trimester is feeling sick and perhaps also vomiting.
This is known as ‘morning sickness’, but it can happen at any time of the day. The exact
reasons why you may get morning sickness aren't fully understood at present. However, it
may be because of the high levels of hormones that your body produces while you're
pregnant.
It may help to:
o eat little and often – you might find blander foods easier to eat
o get plenty of rest
o drink enough fluids
o stay away from smells and tastes that make you feel sick
o take a ginger supplement or drink ginger ale or tea
Morning sickness can make you feel very unwell but it’s important to remember that your
baby is unlikely to be affected by it. However, if you find you can’t keep any food or
fluids down, see your GP or midwife for advice. This is because you may become very
dehydrated, which can lead to complications.
Digestion problems
You may get constipated when you’re pregnant because pregnancy hormones relax and
slow the muscles of your digestive system and bowels. You can help to prevent
constipation by eating plenty of fibre-rich foods, such as green, leafy vegetables and fruit.
Also, make sure you drink enough fluids every day. The relaxation of the muscles in your
digestive system can also increase heartburn. Fatty foods and caffeine can make this
worse, so try not to have these.
Folic acid
It's important to take folic acid, both before you become pregnant (if possible) and until
at least week 12 of your pregnancy. Take 400 micrograms (µg) a day. Folic acid is
important for the development of your baby’s brain and spinal cord. It can prevent serious
problems, such as spina bifida.
If you have a health condition, such as diabetes, you may need to take a higher dose of
folic acid (up to 5000µg a day). Ask your GP or midwife what dose you need to take.
Smoking and alcohol
If you smoke, quitting will protect your baby from a number of health problems that can
occur during your pregnancy. It will also help your baby after he or she is born. This is
because smoking can affect your baby's chance of getting health conditions such as
asthma and colic. Your healthcare team will direct you to sources of support to help you
stop smoking.
The National Institute for Health and Care Excellence (NICE) recommends that you
don’t have any alcohol during the first three months of your pregnancy. This is because
it's linked to a number of developmental problems in babies. If you choose to drink
alcohol while you’re pregnant, limit yourself to one to two units, once or twice a week.
Your baby
During the first 12 weeks of your pregnancy, your baby will begin life as a tiny ball of
cells and develop quickly into an embryo.
By week 10, all your baby’s organs, such as its heart and lungs, are present, even if they
are not yet fully formed. Your baby is now known as a fetus. Your placenta is fully
formed. This structure develops on your womb and is linked to your baby by the
umbilical cord. Through this, nutrients are transferred from your blood into your baby. In
return, all the waste products from your baby are transferred back into your circulation,
so that you can get rid of them.
By week 12, your baby may be almost 8cm long. Their eyes are formed but tightly shut,
and their ears are still forming. Their brain is growing most rapidly, which means that
your baby’s head is much larger than their body.
Second trimester (13 to 27 weeks)
Physical effects of pregnancy on you
Your pregnancy will start to show during the second trimester – exactly when this
happens varies between women.
As your abdomen and breasts grow, you may get stretch marks. These are harmless and
will usually fade after your baby is born. You can try different moisturisers and lotions to
prevent stretch marks but none have been proven to work.
If you were vomiting or felt sick in your first trimester, this will usually get better by the
time you're 16 weeks pregnant. However, you may get backache and pain in your pelvis
because pregnancy hormones cause your ligaments and tendons to relax. This can cause
changes to your posture as your baby grows.
You may first feel your baby move around when you're 18 to 20 weeks pregnant.
However, this can vary – it can be a few weeks earlier if it's not your first pregnancy. The
movements will become much more vigorous and obvious as your baby gets bigger and
stronger.
If you haven’t felt your baby move by the time you're 24 weeks pregnant, contact your
midwife. He or she will arrange for you to have an ultrasound to check all is well with
your baby.
Your baby
In the second trimester, your baby's organs mature and their skeleton starts to harden.
Your baby will have bowel movements and their kidneys also begin to work and pass
small amounts of urine.
By 20 weeks, your baby is able to hear and is covered in fine hair called lanugo. If you
have a scan at this stage, it's often possible to find out whether your baby is a boy or a
girl.
By the end of the second trimester, your baby has a chance of surviving if he or she is
born prematurely. However, your baby would need intensive care.
Also by the end of the second trimester, your baby grows fingernails, and teeth may start
to grow under their gums.
Third trimester (28 to 40 weeks)
Physical effects of pregnancy on you
You may find the extra weight you’re carrying makes you tired, and you may get breathless as
your expanding womb reduces the space for your lungs. Your baby's head may press on your
bladder, so you might need to go to the toilet more often too.
You may have trouble finding a comfortable position to sleep in. This is because your baby's
head may drop down into your pelvis (engage) ready for delivery. This is usually towards the end
of your pregnancy, from around 36 weeks onwards. You might find it helps to put pillows
between your knees and to support your abdomen when you lie on your side.
Braxton-Hicks contractions – practice contractions – can start in the second trimester, but are
much more common in the third. These can be mistaken for labour, but the difference is that real
labour contractions are regular and usually cause some pain. Most women only get one or two
Braxton-Hicks contractions every hour and they fade away rather than getting stronger over time.
Your baby
Your baby's lungs mature throughout the third trimester. Your baby makes breathing movements,
even though their lungs don't work properly until birth. Their eyes can also open and close by
this time. Your baby will kick and stretch and respond to sound.
Your baby will be developing fat stores and it’s likely that they will turn into a head-down
position in preparation for birth.
Weight gain in pregnancy
You will put on weight during your pregnancy – the exact amount varies between women. Your
midwife will weigh you at your first appointment and also measure your height. He or she will
use these measurements to work out your body mass index (BMI). Unless you’re very over- or
underweight, your midwife probably won't weigh you again as it isn't usually necessary.
However, it's possible you might need to be weighed later on.
If you're concerned about your weight gain, talk to your midwife or GP. He or she will be able to
tell you whether it’s too much or too little.
The weight you gain during pregnancy doesn’t mean that you’re getting fat. The extra weight is
made up of:
your developing baby, placenta and amniotic fluid
the growth of your womb and breasts
the increased blood in your circulation
water retention
essential fat stores
How your baby develops in the womb
Click to open full-size image (153 KB)
FAQs
Can I fly when I am pregnant?
Answer
If your pregnancy hasn’t caused any complications to your health, there is no evidence that
flying is unsafe for you or your baby. However, there are recommendations for when it may be
best to stop travelling by plane. Airlines also have their own guidelines and rules for taking
pregnant passengers.
Explanation
If you choose to fly after you're 28 weeks pregnant, your airline will ask you to provide a letter
from your GP or midwife. This will need to confirm your due date and that he or she doesn’t
think you’re at an increased risk of complications by flying. After 37 weeks, if you’re pregnant
with one baby, there is a much higher chance that you will go into labour. This is because most
babies are born within two weeks of either side of their due date. If you’re pregnant with more
than one baby, this chance is higher from week 34 because twins (or more) often have shorter
pregnancies.
Some airlines won’t let pregnant women fly from 37 weeks, while others have an earlier cut-off
date.
Check with the airline before you book tickets. It may be more difficult to get travel insurance
after a certain point in your pregnancy too.
If you have any complications of pregnancy, or other existing health conditions, discuss with
your GP or midwife how flying could affect you. If you’re planning a long-haul flight, your risk
of deep vein thrombosis (DVT) may be higher when you’re pregnant. Make sure you drink
enough fluids and flex your ankles to encourage the flow of blood.
Flying hasn’t been shown to increase your chance of premature labour. However, if you were to
go into labour while on a plane, you’re likely to be far away from medical help. Also consider
the risk of infection and availability of health facilities at your destination in case problems
develop while you’re away.
Can my unborn child hear me?
Answer
Towards the end of your second trimester (13 to 27 weeks), your baby can hear a variety of
sounds from inside and outside your body. These sounds can include your voice and music.
Explanation
From week 16, your baby’s ears are fully formed and will begin transmitting sounds to your
baby. By week 21, your baby will become familiar with the sound of your heart beating and your
stomach rumbling. Your voice will also reach your baby in your womb and he or she will begin
to recognise you speaking. Your baby may also react to noises. Some people like to play music
for their baby to hear when they’re pregnant.
Is it safe to exercise during pregnancy?
Answer
Exercising when you’re pregnant can be beneficial to you and your unborn baby. However, some
activities aren’t suitable when you’re pregnant so you may need to adapt your usual routine as
your pregnancy progresses.
Explanation
There has been a lot of research to study the benefits of continuing or beginning regular exercise
during pregnancy. If you keep up exercise when you’re pregnant, you’re more likely to:
sleep better
have more energy
have better mental health and wellbeing
improve your posture
have less swollen ankles and hands
get fewer varicose veins
If you have developed diabetes during your pregnancy (gestational diabetes), exercise may help
to treat it. It may also help to prevent the condition from developing in the first place. This is
because exercising can help you to control your blood sugar levels better.
You need to take some precautions when choosing what type of exercise to do. Contact sports
aren’t suitable when you’re pregnant because of the risk of injury to your baby. Contact sports
include anything that carries a risk of you being hit in the abdomen, such as judo, squash or
hockey.
Activities that increase your risk of falling, such as horse riding, skiing, gymnastics and cycling,
are also not recommended. When you’re pregnant, you shouldn’t scuba dive, no matter what
your skill level is. This is because your baby can’t be protected against the effects of problems,
such as decompression sickness. Exercising at high altitudes can reduce blood flow to your baby
too.
The hormones you produce when you're pregnant can make your joints weaker. Therefore, it's a
good idea to warm up before you exercise and cool down afterwards.
Don’t do any exercise that involves you lying flat on your back after week 16 of your pregnancy.
This is because your womb can press on the large veins in your abdomen and may disrupt blood
flow to your baby. You may find you get hotter during exercise than you did when you weren’t
pregnant. Make sure you drink enough fluids and don’t exercise in hot or humid conditions.
If you feel any unusual symptoms during exercise, such as dizziness or pain, it's best to stop. See
your GP or midwife immediately afterwards.
My baby is in the breech position. What does this mean?
Answer
The breech position means that, inside your womb, your baby's bottom or feet are pointing down
towards your cervix and vagina. The majority of babies move their head downwards before they
are born. This is the natural position that makes birth more straightforward.
Explanation
By the time babies are ready to be born, only around three in 100 will still be in the breech
position. All the rest will have turned in the womb to be head downwards at some point before
the mother goes into labour.
When you go to your later antenatal appointments, your GP or midwife will check the position of
your baby. If your baby is breech at 36 weeks, he or she may refer you to an obstetrician (a
doctor who specialises in pregnancy and childbirth).
Your doctor will discuss a procedure to try to turn your baby so that they are head down before
birth. In this procedure, your midwife or doctor will place their hands on your abdomen and try
to move your baby inside your womb. He or she will try to turn your baby to do either a forward
or backward somersault. This is called external cephalic version and you will go into hospital to
have it done. An external cephalic version can feel uncomfortable at times – be sure to ask your
doctor to stop if it's painful.
If your baby remains breech, even after an external cephalic version, your doctor will talk to you
about your options for the birth. Depending on your individual circumstances you may choose to
have either a vaginal breech birth or a caesarean. Your doctor will help you to decide the best
option for you.
What will it feel like when my baby kicks? Will it hurt?
Answer
At first, your baby's movements can feel like 'flutters' in your lower abdomen (tummy). Later on,
as he or she grows and develops, you may feel your baby kick, swish or roll.
Explanation
From around week 18, you may begin to feel slight movements from your baby. If you have had
a baby before, you may notice the movements earlier than this because you recognise the
sensation.
As your baby continues to grow and get stronger, you will feel more definite and vigorous
kicking and prodding. As the space inside your abdomen gets more cramped for your baby, you
may be more affected by their movements. For example, your baby can press on your bladder or
keep you awake at night.
Some babies are more active than others but it's important to recognise your own baby’s pattern
of activity. If you notice any sudden change in the pattern of your baby's movements, contact
your GP or midwife. He or she can check that all is well.
When does my baby’s heart start beating during pregnancy?
Answer
The cells that make up your baby’s heart will start making beating movements from very early in
their development. By the end of your first month of pregnancy, your baby's heart will begin to
beat properly. Like all your baby’s organs, the heart is a complex structure that will continue to
develop and grow with your baby throughout your pregnancy. When you’re about six weeks
pregnant, your baby's heart will be pumping blood around its body and out along the umbilical
cord to the placenta.
Explanation
By week 11 of your pregnancy, all your baby’s organs will be present in various stages of
development. Gradually, each organ takes on its complete form, grows larger and begins to carry
out its proper function. By the time your baby is born, he or she can survive outside your womb.
When you're around 12 weeks pregnant you will have your first ultrasound scan. A sonographer
(a person specially trained to carry out ultrasound) will be able to detect your baby’s heartbeat
and listen to it using ultrasound. When you have your 20-week scan, your baby’s beating heart
will be visible. Your sonographer will check everything is working as it should.
Later in your pregnancy, your GP or midwife will be able to hear your baby’s heartbeat with a
stethoscope.
During pregnancy, labour and birth, your antenatal team can monitor your baby’s heart using a
range of other medical techniques. This can help diagnose your baby’s health and can also help if
you need to make decisions about when and where you give birth.
Resources
Further information
National
Childbirth
0300
Trust
(NCT)
330
0700
www.nct.org.uk
Royal
College
of
Obstetricians
and
Gynaecologists
cycle
sheet.
Womenshealth.gov.
www.rcog.org.uk
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