1. Length of Pregnancy.
Due dates are estimates. There is a wealth of evidence that suggests there are huge variations in length of pregnancy.
Your genes, ethnicity and menstrual cycle can all influence the length of pregnancy your baby needs. Baby will send chemical signals to say when they are ready to be born.
2. Ageing Placenta
There is no evidence to suggest that your placenta will start to fail in late pregnancy.
There is no evidence to suggest an ageing placenta is the cause of stillbirths.
In fact, the concern for longer pregnancies is that baby may be large. To grow large, the placenta must still be providing nutrients to them!
3. Your Age
In 2006, a population study by Reddy reported the risk of stillbirth by length of pregnancy and mother’s age. Below are some risks of stillbirths for mothers who are otherwise well.
AGE less than 35 years; 0.53/1000 at week 37-38.
0.87/1000 at week 39-40.
0.69/1000 at week 41.
AGE 35-39 years; 0.67/1000 at week 37-38.
1.24/1000 at week 39-40.
1.05/1000 at week 41.
AGE over 40 years; 0.94/1000 at week 37-38.
1.5/1000 at week 39-40.
2.16/1000 at week 41.
As you can see, the risk is low for all ages.
A study by Knight, 2017, looked at whether being induced lowered the risk of stillbirth at 39, 40, or 41 weeks.
At 39 weeks there was no significant difference in stillbirths or perinatal deaths but an increase in the caesarean rate, from 29% to 35%
At 40 weeks induction reduced perinatal deaths slightly for mothers over 35 years old from 2.6/1000 to 0.8/1000.
Caesarean rate increased from 33% to 39%.
IVF pregnancy
The NICE Guidelines 2008, does not list IVF being a reason for induction of pregnancy.
Mothers who conceive by IVF are on average older. Maternal age maybe the reason she is labelled high risk and for induction at 40 weeks to be suggested. (See Age comments above.)
“There is no evidence to show whether early labour induction improves outcomes for IVF babies.” (RCOG Query bank reply 2013b)
Waters breaking before labour starts.
If you waters release before labour starts, you will be offered an induction if labour hasn’t started by 24 hours.
This is a choice, not a must.
60-95% of labours begin with 24 hours anyway, 90% within 48 hours.
The risk of infection is cited as the reason to induce women. Women are told the risk doubles which sounds scary. But, the risk is low to start with.
This risk is 1/100, compared with 0.5/100 if membranes are intact when labour starts.
Your health.
Maternal health factors such as Obstetric Cholestasis, high blood pressure, Pre-eclampsia, Gestational Diabetes, Type 1 and 2 Diabetes are all risk factors and would need careful consideration and discussion with your Obstetrician.
USEFUL RESOURCES
The AIMS Guide to Induction of Labour.
In your Own Time by Dr Sara Wickham.
Inducing Labour by Dr Sara Wickham.
I hope you find this information useful.
Do get in touch if you would like any more information.
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