Third Trimester

This guide presents a summary of each week both for you as well as for what's happening with the little one inside. So click on the week that relates to you and you can quickly see what may be relevant to you. We have tailored a summary as well as more detail information for those that want a little more detail. Wherever you see italics and or click thru you will be taken to a page with more information. At SRC we are helping women have happier and healthier pregnancies as well as helping them speed up their recovery, so they can do what matters most - is nurturing their newborn children.

  • Week 28

    Your Baby

    • Baby weighs approx 1.2kg
    • Baby very active now
    • Brain now developing grooves
    • More REM sleep

    Focus on you

    • More difficult to sleep
    • Breasts start to produce Colostrum
    • Stretch marks


    Baby’s head to rump measurement is 25cm; head to toe 38 cm. Baby’s weights is about 1.2 kg.

    This week the amount of tissue in your baby's brain increases, and the surface of its brain begins to change from being smooth, to forming grooves, ridges and indentations.

    More REM (Rapid Eye Movement) sleep in week 28, this is important for your baby’s brain. Studies have shown that newborns spend a large portion of their time in REM sleep, so your little one is getting in lots of practice beforehand. The reason REM sleep is important is that this is the time when the areas of your baby’s brain that are associated with the functions of learning and memory become stimulated.


    Around this time your Doctor may order some blood tests, glucose tolerance test, and a test to see if you are anemic.  In addition if you are Rhesus negative, your tests will involve a further antibody screening. You may also have a vaginal swab to test for beta haemolytic streptococcus. These bacteria can be found in the cervix and can go undiagnosed other than by means of this test.   Treatment of this infection pre vaginal delivery is the best way to deal with this infection to reduce the risk of the infection being transferred to baby.

    Gestational Diabetes - this is the second most common disorder in pregnancy. The placenta produces hormones that help the baby to grow and develop, but these hormones also impair the action of the mother’s insulin. This is called insulin resistance. As the pregnancy progresses, the mother’s energy needs increase and her insulin needs are also higher than normal. Some women are unable to produce extra insulin and blood glucose levels rise. 

    Your breasts may start producing colostrum, an early form of breast milk. This is a clear to yellowish coloured thick fluid, which is very high in antibodies and fat. If you have breastfed a baby previously, you may find you produce colostrum a little earlier.

  • Week 29

    Your Baby

    • Weight 1.4kg
    • Airways and lungs maturing
    • Baby can still move round easil

    Focus on you

    • Swollen and puffy legs arms and face
    • dilated veins on breasts more prominent
    • Feeling hot ++


    Baby’s head to rump measurement is 26cm; crown to toe 39 cm. Baby’s weights is approximately 1.4kg.

    Within the last 4-5 weeks your baby has doubled its weight.

    There is still room for complete body movements and changes of position.

    Your baby’s airways are further maturing, the bronchioles and alveoli increasing in number. Surfactant continues to be released. It takes up to eight years for a child’s respiratory system to mature fully so these are still early days.


    Your legs hands and face may be swollen and this can make you feel uncomfortable. This is due to the fact that you have a larger than normal blood volume and your vessels are dilated because of the pregnancy hormones. Veins can leak some fluid into the surrounding tissues making your legs and arms swollen.

    Your breasts begin to feel increasingly heavy and dense. Dilated veins are becoming more and more apparent and your nipples will continue to darken. These changes are essential to prepare your breasts to produce milk for your baby.

    Feeling very hot during the third trimester is very common.

  • Week 30

    Your Baby

    • Baby's brain has grown and nervous system is almost mature
    • Weighs 1.5kgs
    • More fat deposits under skin

    Focus on you

    • Difficult to sleep
    • Feeling tired
    • Varicose veins of legs and vulva


    Baby’s head to rump measurement is 27cm; crown to toe 40 cm. Baby’s weights is approximately 1.5kg.

    Your baby is storing nutrients from your body such as protein, iron and calcium for its own development when born. Your baby will have a 6mth store of iron when born.

    As your baby increases in size it won't be able to cartwheel for much longer as space is becoming more and more limited as the weeks progress. It will be a few weeks before your baby takes up its final position pre-birth. Your baby also begins to control its own body temperature. The hair that covered the skin is now decreasing, while the hair on the scalp lengthens. The head and body are now fully in proportion.

    Your baby’s brain has grown and their nervous system is almost mature. At birth, they will have millions of neurons just waiting for lots of stimulation from you.

    Your baby’s fingernails are almost at the end of its fingertips this week. Some babies’ need their nails cut in the first few days after birth, otherwise they tend scratch their little faces.


    With your ligaments loosening in preparation for birth, it is a good idea to ensure you maintain good posture. With your breasts and belly adding weight to your front, it is just as important not too over correct your spinal curve.

    Insomnia may be a problem for you now, despite how tired you are when you go to bed. This is a common condition in the third trimester and there is little which can be done about it. It can be very difficult to find a comfortable position especially if you are carrying a lot of fluid.

    Varicose veins in your legs and vulva may be an issue. They are not helped by the pressure of your uterus on the major blood vessels in your pelvis. Unfortunately, they are likely to get worse before they get better.  Vulval varicose veins can be very painful. Usually they disappear after birth, though some women can continue to experience them. . If the pain is more than minor discomfort you may find pain relief with SRC Pregnancy Shorts/Leggings.

    This week the placenta weighs on average 430g.

  • Week 31

    Your Baby

    • Baby now 38cm
    • Long periods of REM sleep
    • Brain synapses forming in the millions

    Focus on you

    • Short of breath
    • Iron may be low
    • Feeling of having to visit more often


    Baby’s head to rump measurement is 28cm; crown to toe 41 cm. Baby’s weights is approximately 1.6kg.

    Your baby is spending long periods of time in REM (Rapid Eye Movement) sleep. This is a stage of sleep which is so important that some researchers say humans actually have 3 states of being, awake, asleep and in REM sleep.

    Complex brain and nerve activity continues to occur.  The connections or synapses in your baby’s brain are forming by the millions.


    You may find you suffer from lower leg cramps during pregnancy especially at night. This may be attributed to fatigue of the leg muscles due to carrying extra weight and some breathlessness. Lactic acid may build up in the muscle during the day and cause cramping at night.

    As your uterus is now taking up a large area of your abdomen you may find you need to visit the toilet more often, again due to the pressure of your baby but at this stage of your pregnancy the pressure is on your bladder as space is becoming restricted.

    Your body’s iron stores could be diminishing now, so it’s very important you do what you can to boost them.

  • Week 32

    Your Baby

    • Baby 1.8kg and approx. 42cm long
    • Skin less translucent
    • Baby sleeping most of the time

    Focus on you

    • Braxton Hicks more common now
    • Weight gain in line with baby's growth
    • Bones calcifying


    Baby’s head to rump measurement is 29cm; crown to toe 42 cm. Baby’s weights is approximately 1.7kg.

    Your baby’s skin is less translucent and looks more like the perfect skin of a little baby. More fat cells are being deposited under its skin and plumping out those skin folds.

    With less room to move, your baby sleeps up to 95 per cent of the time, however there will still be  some very active periods.


    Your weight should be going up in line with your baby’s growth. Some women gain as much as half a kilogram per week in these weeks. Fluid retention can also add weight, and this can be largely unavoidable in the third trimester.

    You will not be seeing your practitioner fortnightly until 36 weeks and then weekly thereafter. Problems such as pre- eclampsia, gestational diabetes and premature labour are more common during  the third trimester hence the more regular visits.

    Braxton Hicks may be more common now, as your body prepares for birth.

  • Week 33

    Your Baby

    • Baby producing surfactant
    • Weight 2.0kg approx
    • Amniotic fluid about 1 litre now

    Focus on you

    • Incontinence
    • Indigestion
    • Lots of Braxton Hicks
    • Back pain and Sciatica
    • Top of uterus just below ribs now


    Baby’s head to rump measurement is 30cm; crown to toe 43 cm. Baby’s weights is approximately 2.0kg.

    Your baby’s lungs are maturing even more in week 33. If your baby were born now, it is likely to need some support to help it breathe, but perhaps not. Its own little body is producing surfactant which will help their airways to stay open and not collapse.

    The amniotic fluid which is surrounding your baby is peaking in volume around now. There is about 1L of it. The volume of amniotic fluid is representative of how well your baby’s kidneys are working. They should now be producing around 500ml/day.

    Although your baby may have developed sufficiently enough to support life outside the uterus,  the lungs, along with all the other well-developed organs and digestive tract, will benefit greatly from remaining in the womb to mature until full term.


    Sciatica, lower back pain and pelvic girdle pain can be at their worst from here on. The increased weight of your baby altering your posture and the laxity of your ligaments can make the pain and discomfort almost unbearable for some women.  If the pain is more than minor discomfort you may find pain relief with SRC Pregnancy Shorts/Leggings.

    The top of your uterus (fundus) is now sitting just below your rib cage.

    Mild incontinence may be something that you are also experiencing as your pelvic floor muscles are under strain. This is more common in women who have been pregnant before. When you laugh, sneeze, cough or lift something heavy, a small amount of urine may leak out of your bladder.

    Heartburn may still be a problem; your baby is pushing your stomach and intestines up and out of their normal positions. This means you are unable to digest your food comfortably.

    You may notice an increase in the number of Braxton Hick’s contractions. These should remain painless. They also help to create an increase in the amount of oxygenated blood to the placenta.

    Your weight gain should be between 10 and 12.5 kilos. You may start to gain weight faster from this week on, as your baby also grows very rapidly at this time.

  • Week 34

    Your Baby

    • Lanugo starting to diminish now
    • Vernix still protecting skin
    • Adrenal gland producing cortisol for surfactant production

    Focus on you

    • increasing back pain
    • Indigestion
    • Varicose veins


    Baby’s head to rump measurement is 32cm; crown to toe 44cm. Baby’s weights is approximately 2.25kg.

    All organs are developed fully except the lungs, which will continue to prepare themselves for breathing air after birth. Although the lungs aren't fully developed, almost all babies born at 34 weeks will survive, but will probably experience some initial breathing difficulties.

    Boys’ testicles will migrate down from his abdomen into his scrotum. Some boys will have undescended testicles at birth, though they usually descend within the first year.

    Your baby is opening and closing its eyes easily now, blinking, screwing up its eyes and practicing how to focus (albeit limited). When strong light filters through your abdominal wall your baby may move away from it. The irises are also now light sensitive, and will dilate and contract depending on exposure to light.

    The Vernix which has been covering your baby’s skin is still shielding it at week 34. The soft downy hair (lanugo) which has been covering its skin is starting to disappear this week.

    More cortisol is being produced this week, by the adrenal glands which sit on the top of your baby’s kidneys. Cortisol production allows surfactant production.


    The top of your uterus is about 14.5 centimetres from your belly button this week. Your lungs and diaphragm are being compressed and the baby is sitting high in your belly. It still hasn’t “dropped” into your pelvis.  

    You are hot even when everyone else feels cold; your internal temperature is generally a couple of degrees higher. If you place your hand just above the skin on your tummy now, you’ll feel a radiant heat coming off your body.

    Pre-eclampsia - this is the most common disorder of pregnancy and most often develops in first pregnancies. Symptoms include elevated blood pressure, protein showing in urine and fluid retention.  Blood tests are used to further diagnose and monitor the condition. If pre-eclampsia is suspected the mother and baby will be kept under very close medical supervision. Treatment in the early stages is complete bed rest. If there is thought to be any risk to the baby or mother, labour will be induced.

  • Week 35

    Your Baby

    • Intense brain growth
    • Baby running low on space now
    • Baby gaining approx 250gms per week
    • Amniotic fluid will start to reduce now

    Focus on you

    • Colostrum leaking now
    • Blood for Rhesus Negative screening


    Baby’s head to rump measurement is 33cm; crown to toe 45cm. Baby’s weights is approximately 2.5kg.

    Fat has continued to build up under your baby's skin, and is responsible for providing energy and regulating body temperature. These fat deposits have also changed the appearance of the skin, making it pinker (rather than red) and less wrinkled.

    Lots of brain growth is occurring for your baby this week. The neurons and early connections in their brain are developing.

    Less movement from your baby now. There isn’t the space for it to move around as it was a couple of weeks ago.


    If your baby has been lying in the breech position until now, hopefully this week or next it will turn to be head down. This may give you some relief if that hard and bony head has been sitting up under your ribs. You may even feel pressure on the pelvic bones as your baby's head engages.

    Colostrum may be leaking from your nipples this week. You may notice it has dried and crusted on your nipples when you take your bra off.

    The amniotic fluid surrounding baby will begin to reduce now.

    Due to the displacement of your large blood vessels and the load on your heart, palpitations are very common. You should not feel any pain.

    Your weight gain should be approximately 9-13 kilos. This is an average and will be different for every mum to be.

  • Week 36

    Your Baby

    • Baby now weighs 2.75 kg approx
    • Baby is approx 46 cm long
    • Baby's head may start to engage now
    • Baby's bowel now has meconium in it

    Focus on you

    • Breathing easier now as baby engages
    • frequent visits to the toilet
    • Pelvic Girdle pain


    Baby’s head to rump measurement is 34cm; crown to toe 46cm. Baby’s weights is approximately 2.75kg.

    Your baby’s bowel is filled with meconium, the sticky, black tarry substance which will form its first bowel motion.


    Appointments with your healthcare provider are now weekly.

    Should your baby turn and “engage” into your pelvis this will allow you to breathe more easily. The down side is that you will need to visit the toilet more often.

    Your pelvic bones continue to be influenced by Relaxin and Progesterone and are loosening more in these last few weeks which can mean you are in pain.

  • Week 37

    Your Baby

    • Lanugo now being reabsorbed
    • Vernix being absorbed

    Focus on you

    • Pack your hospital & labour bags
    • Vaginal discharge increases


    Baby’s head to rump measurement is 35cm; crown to toe 47cm. Baby’s weights is approximately 3.0kg.

    Your baby is packing on the weight this week, around 500 grams in fact.

    Lanugo, that soft downy hair which has been covering your baby’s skin is being reabsorbed this week. Much of it will end up in your baby’s gut and will be included along with other waste products in its meconium. Vernix the white greasy coating on its skin will also be reabsorbed.


    You should also get your hospital and labour bag packed and ready.

    Your vaginal discharge will increase now and you could need to wear a liner for extra absorbency. This is completely normal.

    Your total pregnancy weight gain should be between 9 and 13.5 kilos.

  • Week 38

    Your Baby

    • Baby now weighs 3.1 kg approx.
    • Baby now 49cm long
    • Baby's movements slow down

    Focus on you

    • swelling of legs and hands
    • feeling generally "uncomfortable"
    • Breasts producing colostrum


    Baby’s head to rump measurement is 36cm; crown to toe 49cm. Baby’s weights is approximately 3.1kg.

    Baby’s movements have slowed now as there is less and less room to move.


    Finding a comfortable position to lie or sit in can seem virtually impossible.

    Your legs, feet and hands may be very swollen which can be very painful. By now you could be feeling very uncomfortable and wanting to get the baby out!

    Your breasts may be producing even more colostrum this week, to the point where some women will need to use breast pads to absorb leakage.

    You may also experience numbness or tingling in the pelvis. This is also a result of the added pressure of your baby, and is a common complaint at this time.

  • Week 39

    Your Baby

    • More surfactant production
    • Baby now 3.25 kg average
    • Length 50 cm approx
    • Baby still laying down fat

    Focus on you

    • Braxton Hicks contractions continue
    • walking may now be difficult
    • Feeling very tired and awkward
    • Work out your after delivery recovery plan


    Baby’s head to rump measurement is 36cm; crown to toe 50cm. Baby’s weights is approximately 3.25kg.

    Your baby will still gain weight during the last week or two of pregnancy. By now, there is very little room for your baby to move.

    All your baby's organs are developed and in the right place. The lungs are the last thing to fully mature, and your baby is still producing surfactant (the lining of moisture present on healthy lungs). The brain continues to grow and matures during this last weeks.

    Your baby continues to lose the lanugo hair but some of the Vernix remains. This aids in delivery and post birth. Usually, it is left on the baby after the birth for as long as possible.


    As your baby gets ready for labour, you may experience your fundus dropping slightly as your baby sits lower in your body, closer to the birth canal. Your cervix is starting to soften in preparation.

    You will now be about as big as you can get during pregnancy, and no doubt you feel it too! 

  • Week 40-42

    Your Baby

    • Baby's weight can be approx. 3.5kg
    • Baby is now in position to go through birth canal
    • Length can be between 50-52cm

    Focus on you

    • Vulval pressure may increase
    • "Waters" may break now
    • You may experience a "show"


    Baby’s head to rump measurement is 37-38cm; crown to toe 50-52cm. Baby’s weights is approximately 3.4kg.

    Your baby is most likely positioned in readiness for the journey through the birth canal and it is now just a matter of waiting for labour to begin.

    Your baby’s eyes will probably be blue when he/she is born. If their eyes are going to be a colour other than blue, they will change within a few weeks or so of birth. Your baby's fingernails are long, and may need a trim.

    Antibodies continue to be transferred to your baby through the placenta. Breast milk is also an important source of antibodies for your baby after he/she is born, particularly colostrum, secreted for the first few days before your milk comes through.


    Usually by this stage, you are well and truly ready for the pregnancy to be over. Only 5% per cent of babies are born on their due date so it is not uncommon for pregnancies especially first pregnancies to run overtime.

    If you reach 42 weeks, most health care professionals will agree that the baby should be delivered if it is in the proper presentation. You may be monitored for another few days in the hope that you will go into labour, or your health care professional may discuss the possibility of inducing labour or performing a caesarian section.

    The placenta now weighs approximately 650g