Doctors and midwives calculate due dates by taking the first day of your last period as day one and the due date as 40 weeks from then. This is most accurate for women with a regular 28-day menstrual cycle as it is based on 14 days to ovulation and fertilisation occurring approximately then. First time mums might be more likely to go overdue.

Statistically speaking, there’s only about a 5% chance your baby will be born exactly on their due date. Around 57.5% of women deliver somewhere between 39-41 weeks. This is called ‘at the term’ so the baby is considered to be fully developed. Around 26% of mums give birth to their baby between 37-38 weeks and around 7% between 34-36 weeks. A premature baby is the term given to a baby born before 37 completed weeks. Sometimes Mums of premature babies will spontaneously go into labour and sometimes the decision will be to deliver the baby immediately, either by caesarian or by artificial induction of the birth. In addition, multiple pregnancies tend to come early. Underweight women have a higher chance of delivering early as well.

Around 6.5% of pregnancies last longer than 41 weeks, and at that point, hospitals often induce labour, as the rates of stillbirth increase after this time. Births after 42 weeks are called ‘post-term.’

Discuss with your midwife, obstetrician or doctor so you are aware of all the options.

After your dating scan (see our article on scans) your due date may be updated, since it often gives a more accurate reading.

After your dating scan (see our article on scans) your due date may be updated, since it often gives a more accurate reading.

Our nutrition expert, Melissa Little, talks through some of the ideas people have about inducing labour.