Waiting to have a baby in your late 30s and early 40s is becoming more common in the UK, and older mums report that they feel more patient and grounded than they would have if they’d started their families earlier. But there are some risks to delaying pregnancy, too.
For both men and women, fertility decreases with age. And women rarely become pregnant after the age of 45, even with fertility treatment.
The menopause represents the final and definite cut-off point for women’s fertility. This is when your ovaries stop producing eggs and make less oestrogen. The average age for menopause in the UK is 51, but an early menopause occurs before the age of 45, and a premature menopause is before the age of 40.
Usually, fertility starts to decline about 10 years before the menopause. So if your menopause kicks in at 51, the probability is that you will not be very fertile at all after the age of 41. If you have early or premature menopause, your fertility is likely to start reducing at 35 or 30, respectively.
We don’t fully understand why this is, but it seems that women are born with about one million eggs in their ovaries and these are lost through the process of cell death. By the age of about 40, a woman will only have about 10% of her eggs left and most of those eggs will be of poor quality – they are 40 years old, after all – increasing the risk of infertility.
The chances of miscarriage and ectopic pregnancy also increase with a women’s age.
As men age, their sperm quality declines genetically too. This process happens slowly, so there are many examples of much older men still fathering healthy children. However, there is some evidence that the children of older fathers do have an increased risk of developing certain illnesses and disorders, such as an increased risk of various learning disorders and mental health problems. A Swedish study found a link between a father’s age and the risk of his child developing several disorders, including autism, bipolar disorder, attention deficit hyperactivity disorder and schizophrenia.
If you become pregnant when you’re older, there’s a greater chance that your baby will be diagnosed with a chromosomal abnormality. For example, for a 25-year-old mum, the risk of conceiving a baby with Down’s syndrome is about one in 1,250. This compares to one in 100 for a 40-year-old mum.
Older mums also have a greater risk of developing serious pregnancy complications, such as pre-eclampsia, gestational diabetes, placenta praevia (low-lying placenta that may cover your cervix) or placental abruption (your placenta separating from your uterus too early).
If you do decide to get pregnant at an older age, it’s a good idea to have a thorough medical examination first. Eating a balanced diet, exercising regularly and generally taking good care of yourself can also help enormously.