Pregnancy and birth over 35

There are benefits to having a baby after 35 years old. Older women and birthing people are more likely to show an increase in happiness after having a baby than those younger than them (Myrskylä et al, 2017). 

Likelihood of getting pregnant after having sex 

No matter what your age, the biggest factor in getting pregnant is how often you have sex (BPAS, No date). The more you have sex, the more likely you are to get pregnant.

There is a slight increase in difficulty becoming pregnant as you get older. Chances of getting pregnant within a year for women and birthing people are (NICE, 2013):  

• for those aged 19-26 years old, 92 in 100 are pregnant
• for those aged 27-34 years old, 86 in 100 are pregnant
• for those aged 35-39 years old, 82 in 100 are pregnant

If you have trouble getting pregnant over the course of a year, it is likely you will get pregnant if you carry on trying for another year (NICE, 2013).

After the age of 35, the age of the father is as much a factor as the woman’s age (NICE, 2013). 

Likelihood of getting pregnant by artificial insemination  

For those not having sex to get pregnant, the pattern of fertility reducing with age is the same, but with a lower starting point.

• For those under 35, between 50 and 60 in 100 are pregnant after one cycle (or one year of IUI), and between 40 and 50 in 100 are not. 
• For those over 35, between 33 and 50 in 100 are pregnant after one cycle (or one year of IUI), and between 50 and 67 in 100 are not. 

The chances of being pregnant increases with more cycles. 

Risks of having a baby after 35 

The birth of a first baby is more likely to be complicated than having a subsequent baby, no matter how old you are.  

As people get older, the chance of other health issues rises. These health issues are what is relevant, and not the age by itself (Morris et al, 2018).  

Conditions associated with higher maternal age include (Fuchs et al, 2018):

• Chronic hypertension 
• Gestational diabetes 
• Placenta praevia  

Hypertension of pregnancy is more likely in parents under 30, less likely between 30 and 34, and then more likely over 35 (Fuchs et al, 2018). 

Other factors to consider

Older women and birthing people are also more likely to (Fuchs et al, 2018):  

• Use assisted reproduction techniques, such as in vitro fertilisation (IVF) 
• Have invasive procedures in pregnancy, like amniocentesis. 

The chance of having a baby with a fetal anomaly such as Down, Edwards or Patau’s syndromes increases from the age of 25. It is highest over the age of 45. Older women and birthing people are also more likely to have multiple pregnancies (such as twins or triplets) (BPAS, No date).

Is my baby more likely to be born early?

Some research suggests that premature birth (babies born before 37 weeks) follows a U-shaped curve. This would mean that most cases are found in those under the age of 25 or over the age of 40 (Fuchs et al, 2018).  

This research found that premature birth happened naturally to women and birthing people under 25. For those over 40 it followed induction or caesarean birth (Fuchs et al, 2018).  

Other research removed potential reasons for premature birth such as social background or genetic factors. This then found that maternal age had no effect on the chance of premature birth (Goisis et al, 2017).  

Is miscarriage more likely over 35?

The chance of miscarriage increases to older mothers and fathers, and is most likely if the mother is over 35 and the father is over 40. But you are still more likely to have a healthy pregnancy than a miscarriage even if you are over 40 (Miscarriage, why me?).

Implications for care for those over 35

Antenatal care and care in labour

Antenatal care and care in labour for women and birthing people over the age of 35 is the same as for those under 35 unless there are other risk factors (NICE, 2021a; NICE, 2023).

Pre-eclampsia and gestational hypertension

Pre-eclampsia and gestational hypertension are moderate risk factors for women and birthing people over 40. This will lead to them being offered additional antenatal care (NICE, 2019). 

Induction and caesarean birth

Doctors may offer induction earlier (at 40 weeks rather than 41-42 weeks) to reduce any possible impact on the baby (Knight et al, 2017). However, this is not included in the NICE guideline for induction of labour (NICE, 2021b).

Following a caesarean birth, the mother or birthing person has a higher risk of serious complications if they are over 35 years old (Korb et al, 2019).

How to stay healthy

As with any pregnancy it is important to eat healthily and exercise regularly. It’s also important to access antenatal care.  

Smoking was found to be a greater risk of death for mothers or birthing people over 35 than for younger parents (McCall et al, 2017). You can access NHS services to help you quit.

Advantages of being an older parent

Research suggests that older parents may be more likely to look after themselves while pregnant. For example, by drinking less alcohol and seeing the value in antenatal care. This might help offset any negative effects of being pregnant at an older age (Goisis et al, 2017).

Older parents tend to have gained education and social stability, which might explain why they have been found to be happier than younger parents (Myrskyla et al, 2017).