Is a pregnancy achieved through IVF at greater risk? What the studies show

After months or years of trying, a positive test brings with it a new worry: ‘Is my pregnancy at risk because it’s the result of IVF?’ The honest answer can be summed up in two sentences. Yes, certain risks are slightly higher than after natural conception. No, they do not justify anxiety or living as if you were ill: they justify close monitoring.

The figures, for a single pregnancy

The largest meta-analysis on the subject, published in 2016, compared over 160,000 pregnancies achieved through assisted reproduction with over two million spontaneous pregnancies. For a single pregnancy, it found the following relative risks:

A previous meta-analysis, published in 2012, found comparable orders of magnitude for preterm birth, low birth weight and malformations.

How to interpret a relative risk

‘1.6 times higher’ does not mean ‘a 60 per cent risk’. If a complication affects, for example, 5 out of 100 pregnancies in the general population, a relative risk of 1.6 brings this to 8 out of 100: 92 out of 100 pregnancies therefore remain free of this complication. For rare events, such as perinatal mortality or serious malformations, the risk remains low in absolute terms, even when multiplied. Always ask your doctor for the absolute figure that applies to your situation.

IVF or infertility?

Some of these differences do not stem from the technique itself, but from the factors that made IVF necessary: age, infertility itself, and certain associated medical conditions. A major review published in 2019 on the health of children conceived via IVF highlights that studies comparing siblings born to the same mother – one via IVF and the other naturally – find smaller differences. The authors describe the excess risk as ‘modest’.

Fresh or frozen embryos: different risks

Frozen embryo transfers do not have the same profile as fresh transfers. A 2018 meta-analysis showed that following a frozen transfer, the risks of preterm birth, low birth weight and small-for-gestational-age babies were lower than following a fresh transfer. Conversely, the risks of pregnancy-induced hypertension and a baby being large for gestational age were higher, by approximately 30 per cent and 50 per cent respectively. There was no difference in the incidence of malformations or perinatal mortality.

The type of cycle in which the frozen transfer takes place is also a factor

A frozen embryo can be transferred during a natural cycle, involving ovulation, or during a hormone replacement (HRT) cycle, where the endometrium is prepared using hormones and there is no ovulation, and therefore no corpus luteum. However, the corpus luteum appears to play a role in the adaptation of the mother’s blood vessels at the start of pregnancy. In a 2019 American study, pre-eclampsia affected 12.8 per cent of women following a transfer in a hormone replacement (HRT) cycle, compared with 3.9 per cent in a modified natural cycle. A 2023 meta-analysis, covering more than 110,000 embryo transfers, found the risk of pre-eclampsia to be approximately half as high in natural cycles, although the quality of the data remains modest. For women who ovulate, the authors therefore favour the natural cycle. The choice between the two is detailed in natural cycle or hormone replacement (HRT) cycle.

The primary risk factor: twins

None of the above figures carries as much weight as multiple pregnancies. According to US data on assisted reproduction, 64 per cent of twins were born prematurely, compared with 14 per cent of single births, and 55 per cent had a low birth weight, compared with 9 per cent. This is the main reason why single-embryo transfer is now recommended in most situations: see one embryo or two.

Egg donation and maternal age

Egg donation is associated with a higher risk of pre-eclampsia, and the recipient’s age adds its own risks: high blood pressure, gestational diabetes and caesarean section. Age-specific guidelines can be found in pregnancy after the age of 40. For women at high risk of pre-eclampsia, a large randomised trial published in 2017 showed that a low daily dose of aspirin, taken from the end of the first trimester until 36 weeks, significantly reduced the incidence of pre-term pre-eclampsia: 1.6 per cent compared with 4.3 per cent. It is up to your obstetrician to advise whether this applies to you; do not start anything on your own.

What this means for your antenatal care

• Tell your doctor that the pregnancy was achieved through IVF, and specify whether it was a fresh or frozen transfer, a natural or hormone replacement (HRT) cycle, and whether or not it involved egg donation.
• Have your blood pressure checked regularly, and report any headaches, visual disturbances or sudden swelling of the hands and face immediately.
• Screening for gestational diabetes and the ultrasound scan to check the position of the placenta are particularly important at this stage.

Details of how antenatal care is organised in your country, following the first ultrasound scan, are set out in the article on returning home, and information on the early stages of pregnancy can be found in the first ultrasound scan after IVF. If you would like to obtain the information your obstetrician will need from the Greek clinic, please write to me.

Frequently asked questions

Source: https://fertilitegrece.com/en/blog/ivf-pregnancy-risks/ — Triada Baloukoudis, IVF patient coordination in Greece. General information, not medical or legal advice. Printed on

Triada Baloukoudis
Independent IVF patient coordinator in Thessaloniki, with 24 years of experience supporting patients travelling from abroad. More · Contact · Facebook