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Infertility

Pregnancy at an older age

Using the time left wisely and with a clear aim

Today, a large share of women in Europe have their first child after 30, and pregnancies after 40 are becoming more and more common. Biology, however, has not changed. A woman's fertility starts to decline at around 35 and more sharply after 38, and after 42-43 the chances with her own eggs are low.

In medicine, a pregnancy counts as a pregnancy at an older age when the woman is 35 or older at the expected due date. The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) stress in a joint statement that this limit is arbitrary. The risk does not rise suddenly at 35, but gradually, and some risks become significant only from 40.

What changes with age?

The number of eggs falls, and the share of eggs with chromosomal abnormalities rises. After 41, more than 50% of embryos have a chromosomal abnormality. This explains three things: why pregnancy takes longer, why miscarriages become more common and why the success of IVF falls. According to the official figures of the UK authority HFEA (2024), the live birth rate per embryo transfer with a woman's own eggs is about 38% up to the age of 34 and 1-2% at 43 to 44.

The risk of miscarriage rises from 15-20% in women aged 25 to 29 to more than 60% after 40. The man's age also seems to play an important role. Several studies show a link between more miscarriages and possible sperm dysfunction in men over 50. More in the article “Recurrent pregnancy loss”.

When does the assessment start?

The American Society for Reproductive Medicine recommends an assessment after six months of trying from the age of 35, and straight away from 40. The waiting time for younger couples does not apply here. A year lost at 42 counts for much more than a year lost at 30.

What is the right strategy?

At an older age, it is especially important not to lose time with treatments that are not indicated. The doctor treats hormonal disorders that can be corrected quickly (thyroid, prolactin, metabolism) in parallel and not one after the other. Age determines the choice of treatment and the move to assisted reproduction. The older the woman, the sooner an invasive method is needed. After 43, egg donation is the path with the highest chances. The doctor discusses this honestly and respects the couple's decisions.

How should a woman prepare for pregnancy?

With age, conditions that complicate pregnancy become more common: high blood pressure, type 2 diabetes, excess weight and fibroids. Many of them cause no symptoms. This is why preparation before conception is even more important at an older age: checking blood pressure, blood sugar and weight, controlling known conditions well, reviewing medicines, stopping smoking and taking folic acid at least one month before conception.

What are the risks in pregnancy?

The large American FASTER study compared women under 35 with women over 40. In the women over 40, gestational diabetes (7.3% versus 2.9%), a low-lying placenta (1.9% versus 0.5%), placental abruption (1.6% versus 0.7%), preterm birth (11.8% versus 7.8%), low birth weight (7.5% versus 5.2%) and cesarean section (40.5% versus 21.7%) were clearly more common. Loss of the baby around the time of birth was also more common (0.7% versus 0.3%).

A British study of about 76,000 pregnancies also showed a higher risk of preeclampsia in women over 40. According to the joint statement of ACOG and SMFM, high blood pressure before pregnancy, type 2 diabetes, difficulties during labor and admission of the newborn to intensive care also become more common with age.

Stillbirth. The risk of stillbirth rises with the mother's age and with the length of pregnancy after 37 weeks. According to the Royal College of Obstetricians and Gynaecologists (RCOG), the risk at 40 weeks is about 1 in 500 in women over 40 and about 1 in 1,000 in women under 35. A woman over 40 therefore has a similar risk at 40 weeks to that of a woman under 35 at 42 weeks. In women pregnant for the first time, the risk is higher in every week.

How common are chromosomal abnormalities in the baby?

With the mother's age, the risk of chromosomal abnormalities in the baby also rises. According to the joint statement of ACOG and SMFM, the overall risk of a chromosomal abnormality is about 1 in 84 at 35 and about 1 in 40 at 40. For trisomy 21 (Down syndrome), it is about 1 in 294 at 35 and about 1 in 86 at 40. The guidelines recommend offering prenatal testing to all pregnant women regardless of age, either as a blood screening test, with or without nuchal translucency measurement, or as a cell-free DNA test, and a diagnostic test when needed. The woman makes the decision after good counseling.

What care does the pregnancy need?

Aspirin. An age of 35 or more is a risk factor for preeclampsia. According to the joint statement of ACOG and SMFM, low-dose aspirin from 12 to 16 weeks until birth is recommended when, in addition to age, there is at least one other risk factor, for example a first pregnancy, excess weight or preeclampsia in the family.

Ultrasound. A detailed examination of the baby's organs is recommended, especially when no prenatal testing has been done. In women aged 40 and over, the joint statement recommends a growth scan in the last trimester and additional monitoring of the baby from 32 to 36 weeks. For women aged 35 to 39 without other risk factors, the data are not sufficient for this recommendation.

Timing of birth. In women aged 40 and over, the joint statement recommends birth or induction of labor at 39 weeks. A birth in this week does not raise the risk for the newborn, and the rates of cesarean section and high blood pressure in pregnancy may fall. A large randomized trial in the New England Journal of Medicine (2016) showed in women aged 35 and over that induction at 39 weeks does not increase the number of cesarean sections and has no disadvantages for mother and baby. The RCOG also sees induction in women over 40 as a reasonable option.

The gynecologist, and when needed a center for fetal medicine, looks after the pregnancy itself. It is important that the gynecologist has all findings from the time before pregnancy.

When does egg freezing make sense?

For women who want a child later, egg freezing gives the best results before the age of 35. Measuring the reserve and an honest discussion about the chances help to make the right decision in time. More in the article “Diminished ovarian reserve”.

What about mental strain and quality of life?

Wanting a child at an older age often comes with pressure: the feeling that time is running out, comments from other people and guilt about past decisions. Decisions have to be made quickly, and every unsuccessful attempt weighs more heavily. ESHRE sees psychosocial support as a routine part of fertility treatment. At an older age it matters even more, because emotional exhaustion often leads couples to stop treatment early, and the time lost cannot be made up. Honest information about the real chances, without making them look better or worse than they are, helps the couple to decide calmly.

The practice's approach

Sources: American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine – Pregnancy at age 35 years or older, Obstetric Care Consensus No. 11 (2022). Royal College of Obstetricians and Gynaecologists – Induction of labour at term in older mothers, Scientific Impact Paper No. 34 (2013). American Society for Reproductive Medicine – Female age-related fertility decline, Committee Opinion. HFEA – Fertility treatment 2024: trends and figures. Cleary-Goldman J et al., Impact of maternal age on obstetric outcome (FASTER), Obstetrics and Gynecology 2005. Khalil A et al., Maternal age and adverse pregnancy outcome, Ultrasound in Obstetrics and Gynecology 2013. Walker KF et al., Randomized trial of labor induction in women 35 years of age or older, New England Journal of Medicine 2016. Franasiak JM et al., Fertility and Sterility 2014. Gameiro S et al., ESHRE guideline: routine psychosocial care in infertility and medically assisted reproduction, Human Reproduction 2015. Gameiro S et al., Why do patients discontinue fertility treatment? A systematic review of reasons and predictors of discontinuation, Human Reproduction Update 2012.