About one in five women become pregnant naturally in the first three years after successful in vitro fertilisation, according to a new study.
Dr Annette Thwaites of University College London, UK, and colleagues investigated the rate of this type of pregnancy, as few previous studies have been carried out.
The team reviewed and brought together the current evidence and analysed 11 studies deemed reliable.
Rates of spontaneous pregnancy after IVF live birth ranged from ten to 33% of women. It was more likely in younger women, those with a shorter recorded duration of subfertility, and those who had fewer treatment cycles before success.
Overall, the rate was approximately 19%, but the team write in Human Reproduction today that this is a likely underestimate, as some pregnancies were probably not recorded in the studies.
They call for better quality evidence including larger sample sizes, such as national data-linked studies, to give a more accurate estimate of this rate.
Women should be advised that spontaneous pregnancy after an IVF baby is not a rare phenomenon, they say.
Dr Thwaites said that the findings are “in contrast with widely held views – by women and health professionals”.
IVF is now used for a wide range of causes of infertility, including cases where the woman does not have experienced infertility at all, she explained. For example, single women using donor sperm, women in same sex relationships, surrogates or those seeking to screen for serious genetic conditions.
Dr Thwaites said: “Knowing what is possible would empower women to plan their families and make informed choices regarding further fertility treatment and/or contraception.”
Thwaites, A. et al. How common is natural conception in women who have a live birth via assisted reproductive technology? Systematic review and meta-analysis. Human Reproduction 21 June 2023; doi: 10.1093/humanrep/dead121
Leave a Reply