Premature birth

Calculating your due date isn’t an exact science. Here’s what you need to know if your baby arrives early…


Babies born before 28 weeks are actually a rarity, and many mums-to-be who suspect they’re going into premature labour discover that it’s a false alarm. Sometimes doctors will be able to stop a premature labour (using drug treatment) to allow the mum to carry to term. In fact, only about a third of women who go into premature labour will deliver prematurely.


A baby is considered premature (or preterm) if he is born before 37 weeks. But BLISS, the premature baby charity, breaks this down further and categorises 3537 weeks as moderately premature, 2934 weeks as very premature, and before 29 weeks as extremely premature.

‘Unless your baby is extremely premature, there are likely to be no long-term health problems,’ says a spokesperson for BLISS. ‘The vast majority of premature babies go on to live healthy lives that are no different from those of their peers.’ Dr Ronald Lamont, consultant obstetrician and gynaecologist and spokesperson for the Royal College of Obstetricians and Gynaecologists (RCOG) agrees. ‘We don’t get worried about serious health issues for premature babies until they get below about 34 weeks of gestation,’ he says. ‘Fifty per cent of all preterm births occur after 35 weeks, and after this point it doesn’t cause a lot of problems really. There may be a few difficulties with jaundice and feeding but, other than that, not much.’

Little fighters

Very premature babies may need to spend time in hospital before their lungs and brain are fully developed: they may also need some help with breathing to begin with. If the premature baby is very small, he may need to be on a ventilator for some time. Babies born before 25 weeks are also more likely to suffer from respiratory distress syndrome and immature lungs. These problems do not usually occur after 34 weeks. Even before that, survival rates are about 90 per cent by the time you get to 30 weeks.

For women who do go into extremely premature labour, assistance is very close at hand. A spokesperson for BLISS explains: ‘With advances in the medical care babies are receiving, as well as improved knowledge of how to care for them, more and more babies born at 25, 24 and even 23 weeks gestation are surviving and going on to lead healthy and happy lives.’

For more information and support, call the BLISS Family Support helpline on 0500 618140 or visit


How are due dates calculated?

Pregnancy due dates are calculated from the first day of your last menstrual period. A normal pregnancy lasts between 37 and 41 completed weeks, so a baby’s gestation is usually around 40 weeks at delivery. As this method of predicting a baby’s due date only works if you have very regular periods – and always ovulate in the middle of your cycle – it is not always accurate. For this reason, the National Institute for Clinical Excellence (NICE) recommends that all pregnant women be offered an early ultrasound scan between 10 weeks and 14 weeks to determine the gestational age of your baby.

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