Baby’s weight and height may have tapered off as she awaits the arrival of her birthday. The normal length of a pregnancy is regarded as any time from 37 to 42 weeks. However, once your due date passes, doctors will be careful about you being ‘postdates’ and are likely to induce your labour if you go more than 10 to 14 days after your due date.
The universal use of a ’40 week’ gestation was first developed by a German obstetrician called Naegele in the 1800s. He declared that a pregnancy should last 10 lunar months or 40 weeks, which is 280 days, or about 9 calendar months (although we now know that a lunar month is 29.53 solar days, meaning 295 days, which is closer to 42 weeks!)
A study done in 1990 found that the average length of a human pregnancy was about 40 weeks + 8 days for first time mothers, and 40 weeks + 3 days for mothers having their second or subsequent babies. The average Australian baby weighs between 3.5 kg for boys and 3.2 kg for girls, but this can range from 2.8kg to 4.5kg and still be considered “normal”. The average length of a baby is around 50cm from head to toe, but this can range from 46cm to 56cms. The other important measurement that will be taken once baby is born is head circumference, which is usually around 35cm, but can range from 33cm to 37cm. Hopefully you’re getting the idea that there is no such thing as average – especially when it comes to meeting your baby, who will be a unique little being made up of DNA from you and your partner.
Just like adults, all babies are different and develop at varying rates in the womb. This information gives a general idea of your baby’s development and progress.