Risks and Complications in Pregnancy over 40

More women in their 30s are having babies now than in their 20s, as a growing number of women are delaying motherhood as they pursue education and career goals or wait to find the right partner. Delaying motherhood until later in life, has become more common in part due to greater equality and more opportunities, and also the availability of contraception and Assisted Reproductive Technologies (ART).

However, it’s also important to consider the challenges that can be present in a pregnancy over 40. The risks and complications can affect both mother and baby and include genetic risks, miscarriage, high blood pressure, pre-term delivery, caesarean section, maternal death and stillbirth.

Research shows that young people are not aware of the natural limits of female fertility and significantly overestimate the success rates of assisted reproductive technologies. Doctors from Imperial College and Chelsea & Westminster Hospital in London warn that most women are taking measures to preserve their fertility too late, when the ovarian reserve is already diminishing.

Although ART may shorten the time to pregnancy, enables assessment of eggs and embryos and improve the chances of fertility in women over 40, they should know that delaying motherhood comes with a series of risks and complications, writes the Royal College of Obstetricians and Gynaecologists (RCOG).

Risks of pregnancy after 40

Women experience a decline in fertility as they approach their fourth decade in life. A pregnancy after 40 comes with increased risk for the mother and can negatively impact her ability to carry a healthy baby to term. For example, on average a woman in her early 20s will have chromosomal abnormalities in about 17% of her eggs. But, this percentage jumps to nearly 80% by a woman’s early 40s.

These are the main risks of pregnancy after 40:

High blood pressure (hypertension)

Health problems that may have occurred later in life can be exacerbated by pregnancy because of weight gain and increased levels of the hormone progesterone. This can lead to high, or higher, levels of blood pressure.


Pre-eclampsia is a serious condition that complicates 3-7% of pregnancies in women over 40 and is the leading cause of maternal death in childbirth and possible miscarriages. It is said to be characterised by high blood pressure and may result in a fatal seizure.

Gestational Diabetes

Gestational diabetes occurs only during pregnancy and can happen to an otherwise diabetes-free woman, brought on by changes in hormones which make your cells less responsive to insulin. The risk of developing this condition is heightened if a mother is over 35 and medically obese with a BMI of over 30 kg/m2.

Studies link severe gestational diabetes to the risk of stillbirths and developing pre-eclampsia.

Placenta Abruption

Placenta abruption is a serious condition which is seen to be more common in pregnancies in women over 40. Placenta abruption occurs when the placenta separates from the wall of the uterus before birth. It is seen in about 1 in 100 pregnant women and usually happens in the 3rd trimester but can start any time during pregnancy.

Multiple Births

The chances of having twins or even triplets increase as a woman ages, caused by the unpredictable ways in which a woman’s fertilised eggs may divide. Multiple births present serious health risks, including premature birth and a higher chance of miscarriage.

Miscarriage and Maternal Death

Due to the increased chances of chromosomal abnormalities in women after 40, the incidences of abnormal eggs are higher and so are the chances of miscarriage. Unfortunately, around 1 in 3 pregnancies after 40 result in a miscarriage, often within the first 12 weeks of pregnancy.

Complications like those mentioned before – high blood pressure, pre-eclampsia, gestational diabetes and placenta abruption all add to the risk of maternal death during child birth.

Stillbirth or Preterm Baby

Advanced maternal age is associated with an increased risk of stillbirth. Women who are expecting a baby after 40 should be very closely monitored from their 36th week onwards.

Delivering a premature or small baby is another risk associated with advanced maternity.

Chromosomal Complications

With age, the quality of a woman’s eggs deteriorates affecting the way her eggs behave. The most common chromosomal abnormality is Down’s Syndrome.

The Office for National Statistics in the UK found that 1 in 200 babies born to women aged 40 or over have Down’s Syndrome, whereas babies born to mums aged 35-39 have a 1 in 700 chance of having Down’s Syndrome.

Approaching pregnancy over 40 with a good understanding of some of the risks and complications is the first step towards making an informed decision about your options and minimising the risks involved with both a natural pregnancy and pregnancy achieved through Assisted Reproductive Technologies.

For further information about fertility treatments, please don’t hesitate to contact us. Our patient personalised, one to one care means that we are on hand to support you through every stage of the journey. Despite the risks and complications that can occur, our expertise means that we are best place to offer excellent support and provide well-informed advice. We’re here to help you throughout pregnancy and beyond.