Pregnancy - Third Trimester 29-40 weeks

In this section

What’s happening to your baby?

Weeks 29-32

She fully formed now. Her lungs continue to mature. Her brain and nervous system are developed. She responds to light and dark. She can differentiate between sweet and sour tastes. By week 32 she will measure about 39cm in length and her weight will be 3lb 12oz. Her fat stores continue to increase.

Weeks 33-36

Her movements decrease as she has less space to move around. She starts to lose her covering of lanugo. She now urinates and her intestine has filled with meconium (baby’s first bowel movement). She may turn so that her head is facing downwards. Her head can engage into your pelvis around this period of time. At week 36 she weighs in at 5lb 9oz and measures about 44cm in length.

Weeks 37-40

If she is born at this stage she will be classed as full term. The vernix that protects her skin begins to disappear. She has now fully matured and is ready to be born. The average birth weight is 7lb 71/2oz. She will be about 50cm long. She can arrive anything up to 2 weeks after her due date. Don’t worry if she is late, it will all be worth it!


What’s happening to your body?

Weeks 29-32

Your weight continues to increase; you will probably feel that you can’t get much bigger but you will (sorry). You may find that you start to experience Braxton Hicks contractions, which are tightenings across your tummy. These are normal but if you are worried that labour may be starting contact your midwife. You will probably feel hot most of the time.

To alleviate back pain, stand or sit up straight. When lying down, lie on your side with a pillow between your knees; avoid lying on your back.

Weeks 33-36

Your breasts are filling with colostrum and this may leak at times. Leg cramps are common at this point in pregnancy. Your belly button may “pop out” turning from an “insy” to an “outsy”. Your pelvic ligaments soften to prepare for birth. You may have swollen hands and feet due to fluid retention.

Once your baby moves down into your pelvis your breathing should become easier again. You’ll need to wee even more than ever.

Weeks 37-40

Your weight gain will slow down now. You may have a show; when the mucus plug that seals the uterus comes away. Once you reach week 37 your baby is full term and can be born at anytime. Only a small percentage of women give birth on their due date, so try not to be disappointed if you go beyond this. You will be allowed to go up to 2 weeks overdue before labour is induced. Although you may be allowed to go past 42 weeks if you want to avoid induction, but you will have to be closely monitored to make sure the placenta is still doing it’s job effectively.  Try to get plenty of rest.


Weight gain during pregnancy

During the third trimester of pregnancy you need to consume an average of 200 extra calories per day.

But before you reach for the biscuit tin, these should come from the following sources:

  • Protein – lean meat, fish, dairy produce, eggs, beans and pulses.
  • Carbohydrates – wholemeal bread, rice, pasta, cereals and potatoes.
  • Fruit and vegetables.
  • Healthy fats such as olive oil, nuts and nut oils, sunflower oil, oily fish and dairy foods.

A healthy weight gain is seen as being between 22 – 35lbs for a single pregnancy.

The breakdown of weight gain is as follows:

  • An average newborn baby weighs in at around 7lb 71/2oz.
  • Placenta 1lb 6oz.
  • Amniotic Fluid 1lb 3oz.
  • Extra Blood 2lb 12oz.
  • Increased Body Fluids 2lb 2oz.
  • Increased Breast Tissue 1lb.
  • Womb (Uterus) 2lb.
  • Increased Body Fat Layer 7lb 7oz.

For a twin pregnancy expect to gain somewhere in the region of 35 – 45lbs.

If you are worried by any aspect of your weight gain, seek advice from your midwife or GP.


Your baby’s head engaging

When your baby’s head moves down into your pelvis this is known as the head engaging. This can happen anytime from around 34 weeks to during labour. On average it happens at 37 weeks but some factors can affect when this happens. They are:

  • A large baby may not move down to the pelvis until contractions start.
  • If the baby is in a posterior position; when her back is against your back, she may not engage as early.
  • If you have strong stomach muscles, baby may engage later in pregnancy.
  • If you have a narrow pelvis it can take your baby longer to engage.
  • In first pregnancies the head may engage earlier, as subsequent babies tend to drop down near to labour.

Your midwife will measure how far your baby’s head is in the pelvis by dividing the head into fifths. Five-fifths into the pelvis means all the head has descended, where as three-fifths engaged would mean that three-fifths of the head is in the pelvis. The drawback with this method is that some midwives measure in reverse, for example; three-fifths engaged means that three-fifths of the head is still not in the pelvis.  Confused? That makes two of us! Ask your midwife which method she uses.

On your notes ENG stands for engaged whereas N/ENG is not engaged. Once your baby has engaged you should feel a relief from the discomfort you have been feeling such as heartburn and breathlessness, as it is not as squashed up there anymore.. hurray!


Massaging your perineum

Everyone wants to avoid tearing or having an episiotomy during birth. By massaging natural moisturising oils into your perineum (the area between your vagina and your anus), you can improve the elasticity of the skin so that it stretches more effectively during birth.

Oils that can be used include:

  • Almond
  • Wheat germ
  • Olive
  • Pure Vegetable Oil
  • Vitamin E

It would be advisable to start massaging your perineum around the 33rd week of pregnancy, for a couple of minutes a day. An effective way to do this is to insert your thumb into your vagina to massage from the inside, whilst massaging with your fingers on the outside.


Braxton Hicks contractions

Braxton Hicks contractions; otherwise known as practise contractions were named after the doctor who first referred to them in 1872. They are caused by the uterine muscles contracting. You have these contractions throughout most of your pregnancy, but will only become aware of them towards the end of the second trimester or during the third trimester. They will become more apparent the further through pregnancy you get.

Unlike contractions that you have during labour, Braxton Hicks contractions are not close together and do not happen regularly. Although they can become uncomfortable they should not be painful or intense. They will not become stronger or more frequent, unlike proper contractions.

To ease any discomfort:

  • Have a relaxing bath.
  • Rest in a comfortable position.
  • Try walking around.
  • Drink plenty of fluids.

If the contractions become painful, intense or regular (more than 4 per hour) then consult your midwife or GP.


Pelvic floor exercises

The pelvic floor muscles stretch along the base of your pelvis. They keep the bladder closed to prevent incontinence. They enable us to control when we pass a stool and when we break wind. The pelvic floor muscles also support the organs in the pelvis. They can enhance your sexual pleasure and that of your partner when well toned.

One of the best pieces of advice that you can follow during pregnancy, is to do your pelvic floor exercises. It is not stressed enough how important it is too look after them. You should start exercising them from the third trimester of pregnancy and continue after birth. These exercises should be done every day.

The best way to find how to tighten your pelvic floor muscles, is to have a wee and then try to stop midflow, these are the muscles you need to use. Don’t do this frequently when weeing, as it can stop you from emptying your bladder properly. Now tighten these muscles and hold for the count of 10, repeat 10 times. Then squeeze these muscles and release quickly, do these 10 times. Do each set of exercises 5 times each per day, fitting them into your daily routine.


A show – mucus plug

Towards the final stages of pregnancy, around week 37, you may have a show. This means that the mucus plug that has sealed the cervix during pregnancy comes away. It can be lost up to a few weeks before birth. This jelly like plug is yellowish and can be streaked with blood. You may not even be aware when this plug has come away. There is no need to contact the midwife when you have a show, as it does not necessarily mean labour is about to start.


Waters Breaking

When the membranes of the amniotic sac rupture, this is known as your waters breaking. Your baby is protected in this sac surrounded by amniotic fluid, so when this bag breaks the amniotic fluid is released. Some women experience a gush of fluid when this happens, whereas others find they leak a small flow of fluid over a longer period of time.

When your waters break this usually signifies the onset of labour and the majority of women go into labour within 48 hours. If your labour has not begun after 48 hours, the medical team will want to induce labour as there is a significant risk of infection. Once your waters have broken you should refrain from bathing and intercourse. The fluid released should be clear, not brown or green, which would indicate the presence of meconium (baby’s first bowel movement). Meconium in the waters can show that the baby is in distress, so you would need to go to the hospital straightaway.

Some women find that their waters break during established labour. Others will have their membranes ruptured by the midwife to speed up labour. In rare cases babies have been born with the sac of fluid still intact, which is then opened by the midwife.


Birth partner

The role of a birthing partner is to support you during labour and birth. They should offer you both emotional support and encouragement. They also need to be familiar with your birth plan so that they can communicate your wishes to the midwife. It would be beneficial for your birth partner to attend some antenatal classes with you, so that they can remind you on issues such as breathing properly  (you will probably respond to any advise with a variety of obscenities, but this is a good emotional release for you!).

Hospital policy usually allows one or two birth partners during a vaginal birth. If you have a caesarean it will probably be one, check with your hospital to find out their rules relating to this. In some cases your partner may not be able to accompany you during an emergency caesarean; this would depend on the circumstances. During a home birth you could have more people present (leave room for the midwife though).

Most women choose one or two of the following as birthing partners:

  • Partner.
  • Friend / mum / sister.
  • Doula – this is a professional birth companion, with knowledge and experience of birth. She can offer support and advice during labour and birth. She will meet with you during pregnancy so that she is clear of your wishes and aims for labour. She can discuss the best way to meet these goals. She may also be trained in complimentary therapies such as reflexology, massage and visualisation techniques. A doula can also instil confidence in a nervous birth partner. The UK Doula Association will be able to provide you with more information and a list of doulas in your area.

    More information about the UK Doula Association >>