Pregnancy Guide: Third Trimester

You’ve made it to the final leg of the journey – and what a journey it’s been. Now it’s time to start preparing for that special day, and this is an important time for Dad to get involved as Mum will be needing lots of rest. You may be counting down the days until that special one, but only 5% of babies are born on their actual due date, so it’s important to be prepared for anything.

We’ve put together some of the changes that your body and baby might go through in weeks 29 – 40+, along with some tips on how to prepare and make this life changing part of your journey a little bit easier.

Don’t forget to check out our previous posts on your first and second trimesters, and look out for further posts in this series.

Pregnant mum holding her bump with daughter on lap


Physical changes

  • You will grow and grow. At week 29 you may not be able to see your legs when standing.
  • You may experience more heartburn as your womb pushes into your stomach and shortness of breath as it pushes on your diaphragm.
  • Your belly button can go from an innie to an outie!
  • Nails might grow faster and skin can plump out, reducing wrinkles.
  • If you didn’t see them before, you may start to notice varicose veins and stretch marks.
  • Similar to your previous trimesters, migraines, haemorrhoids, cramps, back pain and forgetfulness can continue.
  • The food you eat now travels through you slower so that your baby can absorb it better. This can lead to more constipation and gas.
  • You may feel even more tired and a bit clumsy – your weight gain along with ligament changes mean you might feel a bit off balance.
  • Ligaments in feet can spread permanently. Some women go up a whole shoe size during pregnancy.
  • Restless leg syndrome is common in this trimester.
  • Braxton Hicks contractions are also common. You’ll feel tightening in your stomach but they shouldn’t be painful.
  • You are more susceptible to urinary tract infections, so speak to your healthcare professional if you feel burning when you wee.
  • Don’t worry if you leak a little bit of wee when you cough or laugh; it’s due to your pelvic floor muscles relaxing in preparation for labour and is completely normal.
  • ‘Bloody show’ (a mixture of mucus and a little bit of blood) may appear in your toilet or underwear – you’re probably only a few days away from labour at this point!
  • Once your water breaks, labour will be just around the corner.
  • Labour starts slowly with contractions spaced widely apart. Once they’re every 5 minutes and last for 30 or more seconds, call your midwife or labour ward that you’re going to or, if you’re having a home birth, call your midwife to come to you.

What’s going on inside?

Your baby will be kicking lots now, and by counting the kicks, you can ensure everything’s going well. You may need to contact your healthcare professional if you feel fewer than 10 movements in 2 hours (not just kicks but any movement), although your baby may just be resting – try eating a light snack to perk them up and start counting again.

  • Week 29 – your baby is half the size they will be at birth
  • Week 30 – they’re fully developed, but there’s still a little bit more work to do
  • Week 31 – they can tell when it’s light or dark outside your tummy
  • Week 32 – they can have dreams at this stage!
  • Week 33 – they’re the size of a pineapple
  • Week 34 – they weigh around 5 pounds
  • Week 35 – they might ‘engage’ (turn so their head is down ready for birth)
  • Week 36 – they’re around 50cm long and quickly gaining fat
  • Week 37 – they’ll move further into the pelvis
  • Week 38 – they’re full term and the size of a marrow
  • Week 39 – they’re the size of a small watermelon and boys tend to be a bit heavier than girls
  • Week 40 – if they haven’t already, they’ll be all set to make their debut

Did you know: by week 40, your uterus has stretched to around 500 times its original size!

Emotional changes

  • You may feel the sudden urge to clean and prepare – this is called nesting. It’s normal to want to have your house ready and free of germs for your newborn, but if you find yourself cleaning the same things over and over again you should talk to your midwife, as this may be a sign of a mental health problem.
  • You may experience a ‘natural high’ over the excitement of having your baby.
  • Mood swings similar to the first trimester can return as you edge closer to the reality of having your baby. Remember, 1 in 5 women and 1 in 10 men suffer from depression during or after pregnancy, so it’s important to contact your healthcare professional if either of you are experiencing unusually low moods.
  • You may start to have anxieties over the birthing process: wondering how you’ll cope with contractions, pain relief decisions, getting to the hospital in time, having a caesarean, delivery complications, etc. It’s normal to worry about these things, but speak to your midwife if worries are excessive and affecting your everyday life.
  • Some women find breathing exercises and medication can help to calm their mind. If that’s not for you, try focusing on doing things you like – reading, walking, spending time with friends, etc.

Did you know: you may lactate at the sound of a crying baby before you’ve even given birth! This happens when hormones stimulate the mammary glands to prepare you for feeding your baby.

Difficult issues

Preterm labour

  • Some women are at greater risk for preterm labour, such as those pregnant with multiples, those who have had previous preterm births, have an infection in the amniotic sac or have an excess of amniotic fluid.
  • Look out for abnormal vaginal pressure or discharge, diarrhoea, lower back pain or tightness in the lower abdomen.
  • Premature babies are at higher risk for health problems, specifically to do with their lungs, as lungs don’t develop until quite far into the third trimester.
  • Risks are also increased for women who are underweight or overweight, so ensure you’re eating a balanced and healthy diet, and getting enough gentle exercise.

Other complications

  • Contact your midwife if you feel that your baby’s movements are slowing down, as this may be a sign that they’re having problems.
  • Some itchiness is normal, but if you have lots, especially on the palms of your hands or soles of your feet, contact your midwife as you may have obstetric cholestasis which affects 1 in 140 pregnant women in the UK and requires medical attention.
  • Tell your midwife if you’ve been suffering from severe headaches, blurred vision or excessive swelling in the hands, ankles or face as these can be signs of pre-eclampsia.
  • Group B Streptococcus is a normal bacterium that’s carried by 25% of women, but if it’s passed to the baby during labour it can be fatal for them. If it’s been detected, you’ve had a baby who’s been infected previously or you go into labour before 37 weeks, you’ll be given antibiotics which can prevent the infection in newborns.
  • Around 16% of women develop gestational diabetes during pregnancy. It normally disappears after birth but it can cause problems for the baby such as macrosomia (excessive growth) which increases the likelihood of a caesarean and risks of birth injuries. It’s important to get tested for GDB so that it can be caught early and managed properly.


What to eat

Pregnant lady in third trimester eating salad

  • From the start of the third trimester you’ll need 200-300 more calories a day.
  • As your baby grows, you may have trouble eating normal sized meals. Try smaller, more frequent meals.
  • Continue with the nutritious foods you ate in your first and second trimester. Focus on fibre, protein, calcium and iron with foods such as leafy green vegetables, nuts, seeds, pulses, wholegrains, fruit, yoghurt, cheese, chicken, lean meat, oily fish, eggs, etc.
  • When you cook, make extra and freeze it so that you have meals for when you’re home from the hospital and too busy and tired to cook.
  • Continue to drink lots of water.

Things to avoid

  • Sleeping on your stomach or back which can decrease blood flow and cause shortness of breath. Sleeping on your back during this stage has also been linked to increased risks of stillbirth.
  • Continue to avoid strong chemicals, cigarettes and alcohol, and foods that can be bad for you and your baby: raw, seared or rare foods, unpasteurised dairy, raw eggs, raw bean sprouts, high mercury fish or foods with lots of preservatives or chemicals.
  • Saunas and steam baths – they can change your internal body temperature and create problems for your baby.
  • Sitting for extended periods. This can become uncomfortable and is bad for your circulation.
  • Holding onto your wee – this can cause UTIs.
  • Flying at this stage is not recommended as it increases your risks of developing blood clots and the high altitude can interfere with oxygen getting to your baby.

Did you know: 1 in every 4 to 5 women in the UK have caesareans. They’re done for many reasons such as your baby being in the wrong position, preeclampsia, infections, a low-lying placenta, etc.

Well-being tips

  • If you’re suffering from restless leg syndrome, try stretching your legs, hot or cold packs, warm baths, massages or relaxation techniques.
  • It’s advised that you sleep on your left side during this part of your pregnancy – it’s the safest position for you and your baby.
  • Get as much rest as you can. Around 78% of pregnant women experience sleep problems, and they’re more prominent in the third trimester, so it’s important to rest even if you can’t sleep.
  • Practice slow rhythmic breathing which can help you to feel more relaxed and be able to cope better with labour.
  • Massage the perineum (the area between the vagina and the anus) to reduce chances of it splitting during birth.
  • If your feet are swollen, rest with them up at a level higher than your heart for about an hour each day.
  • Grab some ‘me’ time before the baby arrives – pamper yourself, get together with friends or try a mum-to-be spa day.

Pregnant couple looking at baby scans and shoes

To do

  • Decide on a birth partner and a backup birth partner, just in case your first choice is delayed getting to the birth for any reason. They should be understanding, respectful, and feel comfortable in a (probably messy) hospital environment.
  • Finalise your birth plan: birth partner, pain relief, if you want an injection to deliver the placenta, etc. Your midwife can help you come up with this plan.
  • Pack your hospital bag – do it early in this trimester so that you’re not panicking at the last minute. Pack comfy clothes and slippers, toiletries, snacks, water in a spray bottle, chargers, a going home outfit for your little one, etc.
  • If you have other children, organise childcare for when you go into labour.
  • If you haven’t already, join an antenatal class to prepare you for what will happen during labour.
  • Continue to stay active. If there are no complications with your pregnancy, it’s OK to stay active right up until you give birth.
  • Prepare for your newborn: clothes, a cot, a pram, etc. Start by making a list of what you think you’ll need and focus on the essentials, as other things can be bought once the baby has arrived or may be given to you at your baby shower! Make sure to wash all baby clothes with a hypoallergenic detergent to remove any irritants.
  • If you’re planning on breastfeeding, get fitted for and buy some feeding bras.
  • Hire or buy a TENS machine which can help with pain relief during labour.
  • Start thinking of baby names! Although there’s no rush – you have up to 6 weeks after your baby’s born to register their birth (or 21 days in Scotland).


  • If this is your first baby, you will have an appointment at 31 weeks to discuss tests from your last appointment, measure your uterus and blood pressure, and test your urine for protein.
  • At 34 weeks, you will have a similar appointment, and also receive information on caesareans.
  • At 36 weeks, you will have a similar appointment where your midwife will also check the position of your baby and give you information on things such as breastfeeding, caring for your baby, postnatal depression, etc.
  • At 38 weeks you will have a similar appointment and discuss what happens if your pregnancy lasts longer than 41 weeks.
  • If this is your first baby, you will have a similar appointment at 40 weeks.
  • At 41 weeks you may, again, have a similar appointment, which will include a membrane sweep and a discussion on induction options. 1 in 4 women who have a membrane sweep go into labour within 48 hours.
  • At 42 weeks, if you’ve not had your baby and chosen not to be induced, you’ll be offered increased monitoring.

And we’ve made it! Once you’re across that finishing line you’re going to feel a rollercoaster of emotions. It’s OK to feel a little lost at this time – bringing a tiny human into this world is a huge thing and your body and mind have been through so much in these last 9 months.

We hope this has helped you to understand what can happen in this magical part of your pregnancy journey, and we hope that everything goes well with your beautiful bundle of joy.

Let us know in the comments below if you have any questions or tips on getting through the third trimester!

Infographic with info on the third trimester