Pregnancy Third Trimester

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(Week 27-40+)

Week 27 The foetus measures about 34cm and weighs about 800g.

Week 28 You may be asked to attend a routine check up to test for pre-eclampsia. Women with Rhesus negative blood will also be tested for antibodies.If the mother has Rh negative blood but the baby is Rh positive she can develop antibodies to her babies blood during labour. This is not a problem in the first birth but can affect subsequent pregnancies and result in stillbirth. Fortunately treatment is simple and effective.

Week 29 Some women develop restless leg syndrome in their third trimester.This is sensations such as crawling tingling or even cramps and burning inside the foot or leg - often in the evening and at night disturbing sleep and making the mother feel she needs to get up and walk around. No-one knows what causes this harmless but irritating condition.

Week 30 Braxton Hicks contractions may begin around now. They are practice contractions which don’t usually hurt. These are irregular, painless contractions which feel like a squeezing sensation near the top of the uterus. If contractions become painful or occur four times an hour or more, the woman should call a doctor as she may be in early labour.

Week 31 The foetus can see now and tell light from dark. Your breasts start to produce colostrum about nowThis high calorie milk is produced by most pregnant mothers to feed the baby for the first few days after birth before normal milk starts.

Week 32 You may be asked to check in for another antenatal appointment with your midwife. The foetus is about 42cm and weighs 2.2kg. A baby born now has a good chance of survival.

Week 33 From now the baby should become settled in a head downwards position. A midwife or consultant can attempt to help to move it if necessary.

Week 34 The mother may find it more difficult to eat full meals as the expanded uterus presses on her stomach.

Week 35 If the mother has been told she may need a planned caesarean, now is a good time to discuss it further.

Week 36 The baby´s head may engage in the pelvis any time now.

Week 37 The baby´s lungs are practically mature now and it can survive unaided. The final weeks in the womb are to put on weight.

Week 38 Babies born from this week onward are not considered early.

Week 39 Another ante-natal appointment. The mother has reached her full size and weight by now.

Week 40 In theory the baby should be born this week. The mother´s cervix prepares for the birth by softening.

Week 41 First babies are often up to a week late but if there are signs of distress to mother or child the birth will be induced.