Women who have conceived through IVF may be more likely to develop pre-eclampsia during pregnancy than pregnant women who have not, according to a recent study in the US. The researchers, who are presenting their findings at this year's American Society for Reproductive Medicine conference in Orlando, suggest that exposing embryos to laboratory conditions during IVF may lead to poor development of the placenta and its blood supply.
Analysis of data from six previously published studies showed a 40 percent increase in risk of pre-eclampsia in women who conceived by IVF compared to non-IVF assisted pregnancies. According to information from NHS Choices, mild pre-eclampsia can affect up to ten percent of all first-time pregnancies in the UK. The risk to IVF patients reported in this recent study would be equivalent to an increase from 10 to 14 percent. The findings also suggested the risk of a more severe form of the condition that can be life-threatening to both mother and baby increased from two percent for all pregnancies in the UK to nearly three percent for IVF pregnancies.
The authors conclude that this evidence may support the theory that growing eggs outside of the body during IVF treatment can reduce their ability to implant successfully into the uterus. They suggest this can prevent the correct formation of the placenta - the organ that delivers blood, nutrients and oxygen from mother to baby - leading to pre-eclampsia. But the exact causes of pre-eclampsia are still not well understood and the study itself provides no direct evidence of changes to the egg or consequent poor implantation.
However, women undergoing IVF may have a higher risk of developing pre-eclampsia for a number of reasons. First-time mothers and women who are older, expecting more than one baby, have reported fertility problems or have a family history of pre-eclampsia have been identified as being more likely to develop the condition. Although the current study accounted for the age of the mother, the number of previous pregnancies and multiple births, they did not consider all currently identified risk factors.
Charles Kingsland, a consultant gynaecologist at Liverpool Women's Hospital and a member of the British Fertility Society, told the Telegraph that women who struggle to conceive 'will have more difficulty in maintaining the pregnancy'. He urged women undergoing IVF not to be worried by the findings.
Pre-eclampsia develops during the second half of pregnancy when there has been a problem with the formation of the placenta. This leads to high blood pressure and fluid retention in the mother and growth restriction for the baby. The condition is usually mild but approximately six women and several hundred babies die every year in the UK due to pre-eclampsia and related complications.
This study has yet to be published in a peer reviewed journal and the researchers only looked at a subset of studies looking into the relationship between IVF and pre-eclampsia.