Your Body & Baby in the Third Trimester

The third trimester starts around week 27 and goes until week 40 and beyond. During this final phase, you will notice many changes in your body as your pregnancy gets closer to the end. Each week, you might feel significant shifts as your baby grows. You may experience a heavier belly, Braxton Hicks contractions that can feel like real contractions, and common symptoms such as heartburn, shortness of breath, or varicose veins. It can feel like your body is both delicate and strong at the same time.

Your midwife or doctor will help you with your antenatal care as you prepare for labour and birth.

Illustration of four pregnant women in their third trimester sitting together in an antenatal class, listening and smiling, with soft lotus flower accents in the background.

As you move through the final weeks before birth, your body works incredibly hard to support both you and your growing baby. By week 30 or week 31, your uterus has risen high enough to gently press on your lungs, which can make shortness of breath more noticeable. Many pregnant women also find that heartburn becomes more frequent, a mix of your digestive system slowing down and the natural pressure from your beautiful bump.

Your weight gain may level out at times, and by week 32 or week 33 you might notice some swelling in your ankles or hands. This is common, and resting with your feet up can help.

By week 34, your uterus may be sitting as high as your ribs, which can bring occasional rib aches. You may also see more visible stretch marks or varicose veins, natural signs of the amazing changes your body is going through. Many women begin to notice Braxton Hicks contractions more often during this stage. Think of these as gentle practice sessions, your body’s way of preparing for the magical work of labour when the time is right.

How Your Baby is Growing in the Third Trimester

From week 27 to week 40, your baby experiences some of the most rapid growth of the entire pregnancy. By the start of the third trimester, your foetus is about the size of a large cauliflower and weighs around 1 kilogram. Over the coming weeks, your baby’s organs mature, fat layers develop under the skin, and the brain forms more complex connections.

By week 30, your baby’s eyes can open and close, and they respond to light and sound. The placenta continues to supply oxygen and nutrients while also filtering waste. Around week 33, the immune system starts to strengthen, preparing for life outside the womb.

From week 36 onwards, the baby’s head often moves into a head-down position ready for birth. The lungs are now well developed, although they will continue to mature right up to delivery. By week 40, your baby may weigh between 3 and 4 kilograms and measure around 50 centimetres long.

You might notice stronger kicks, stretching movements, and rolling sensations as your baby grows. Although space in the womb becomes more limited, the movements can feel more deliberate and reassuring.

What Changes in Your Body and Baby

Braxton Hicks and Practice Contractions

From around week 36 onwards, you may start to notice Braxton Hicks contractions more often. These gentle, irregular tightenings of the womb can feel like an unexpected squeeze or a tightening across your belly. They are your body’s way of quietly rehearsing for the big day, and while they can be a little uncomfortable, they are not the start of early labour.

Often, Braxton Hicks are short-lived and fade if you change position, take a gentle walk, or sip some water. Think of them as your body’s reminder that it knows exactly what to do when the time comes.

If you are ever unsure whether you are feeling practice contractions or true labour, your midwife is there to guide and reassure you. It can help to make a note of any patterns or changes so you feel more in tune with your body as you get closer to birth.

Monitoring Weeks 37 to 40 and Beyond

By week 37, your baby is considered full-term, which means you are closer than ever to meeting them. You might notice new aches in your hips as your baby drops lower into your pelvis, making more space for their big debut. Between week 38 and week 40, your body is in full preparation mode. You may feel stronger and more frequent Braxton Hicks contractions and a constant sense of pressure in your pelvis, especially as you get to week 39 or week 40.

If any common pregnancy symptoms suddenly intensify, for example, swelling in your face, blurred vision, or rapid weight gain, it’s important to check in quickly with your midwife or doctor. These can be signs of conditions like preeclampsia that need prompt attention.

Use this time to lean on your antenatal classes, finalise your birth plan, and take moments to connect with your baby. Whether it is through gentle belly rubs, talking to them, or playing your favourite calming music, these small rituals can help you feel grounded as you approach labour.

Cravings That Carry into the Third Trimester

Cravings often start earlier in pregnancy, but they can continue into the third trimester, sometimes with quirky twists. You might find yourself crunching on ice, dipping pickles into peanut butter, or even pairing ice cream with salty snacks. Some mothers develop a sudden love for fresh fruit, while others enjoy hearty comfort meals they never craved before.

Most cravings are harmless and simply reflect shifts in taste or your body’s changing needs. However, if you notice unusual cravings for non-food items like clay, soil, or ice chips, it could signal a condition called pica, which can sometimes be linked to iron deficiency. Mention these cravings to your midwife or doctor as part of your antenatal care so they can help keep both you and your baby healthy.