It was a German obstetrician Franz Naegele (1778–1851) whose rule calculated the length of pregnancy. His rule adds nine months and seven days to the first day of the last menstrual period.
This rule doesn’t take into account a person’s age, race, previous pregnancies, and births. In addition, many women regard the 40‐week date as a deadline, which if crossed, may then place the baby under stress – this is not the case.
Considering these calculations, devised in the 1700s, are hugely out of date, fantastic new research published in April 2021 in the Australian and New Zealand Journal of Obstetrics and Gynaecology analysed the medical literature relating to “variables on the length of pregnancy, the expected date of confinement, and prolonged pregnancy.
The research showed that “a number of factors were found to significantly influence the length of a pregnancy, including ethnicity, height, variations in the menstrual cycle, the timing of ovulation, parity and maternal weight.” (Lawson 2020).
See the full paper: https://obgyn.onlinelibrary.wiley.com/doi/10.1111/ajo.13253
Your due date is the date when your baby will most likely not make an appearance.
Did you know, the World Health Organisation (WHO) does not talk about ‘due dates’, they talk about your ‘due period’. And your ‘due period’ can be between 37 and 42 weeks pregnant. I think you will agree: that is quite a window.
96% of babies do not arrive on their due date but yet, there is so much pressure surrounding this date. When you decide to tell people you are expecting a baby “When is your due date?” is always one of the first questions you are asked.
Statistically, from the beginning of your pregnancy you are putting pressure on yourself and your baby regarding a date. It might not seem like a big deal at the beginning of your pregnancy but as this date draws closer you will hear things like:
Do you think the baby will be late?
Were you late when you were born?
Mine was overdue too.
Do you think the baby will be on time?
All my babies were early.
Being late or overdue isn’t a positive thing in everyday life and this poor baby, before it is even born it is late.
A few facts to think about:
- 96% of babies don’t come on their ‘due date’.
- 87% of spontaneous births happen in week 41+.
- One in four babies are induced.
- Ultrasounds have an error margin of +/- 5 days, meaning that your ‘due date’ may not actually be your due date!
- Your baby releases a protein into your system which signals to the brain to start birth. This happens after the final organ is ready, the lungs. This can happen from 37 weeks pregnant.
It’s clear that, left to their own devices, nearly nine out of 10 babies will make their appearance of their own accord, naturally, after the due date. And, whilst it’s important to be looking out for signs that your baby is struggling. 40+ weeks you should have more monitoring, sometimes daily monitoring is offered.
Are you feeling pressured surrounding your due date, from friends and family or your medical team?
If this is you, what can you do?:
- Nothing. If there’s nothing wrong, do nothing. Wait. Sleep. Go for nice walks. Take warm baths.
- Have a due month. “I am due in February” or “I am due at the beginning of March”.
- Breathe and take your time. If there’s no emergency and no one’s at risk, try and stay calm.
- If your doctor hasn’t identified any real risks to you or your baby’s health, feel able to say no to medical intervention. Your birth, your choice.
Not all berries are ripe and ready at the same time, babies are no different.
Pause, breathe, stay call.
It’s your baby, your birth, your choice.
Trust your instincts.