Infertility treatment linked with slightly higher risk of pregnancy complications

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Women who become pregnant using infertility treatments, such as in vitro fertilization, have a slightly higher risk of a complication according to a new study by researchers at ICES, Research Institute of the McGill University Health Centre (RI-MUHC) and St. Michael’s Hospital. These complications can include bleeding, serious infections and admission to the intensive care unit (ICU) around the time of delivery.

The rate of such severe complications in Canada is approximately 10 to 15 for every 1,000 births. Maternal deaths are even rarer, occurring in 10 or fewer per 100,000 births. During pregnancy, such complications are often sudden and difficult to predict. Thus, it is important to identify women who may be at risk for these events so that negative outcomes, including death, may be averted.

"We found that 30.8 per 1,000 of the women in our study, who received an infertility treatment, experienced a severe pregnancy complication. When compared with a group of women of approximately the same age and with similar characteristics who gave birth without the use of infertility treatment, 22.2 per 1,000 of the untreated women experienced a severe pregnancy complication," says lead author Dr. Natalie Dayan, Director of Obstetric Medicine in the Division of General Internal Medicine at the McGill University Health Centre and a clinician-scientist at the RI-MUHC.

"It is important to remember that the absolute number of women who develop these complications remains quite small, meaning that for the vast majority of women or couples who cannot conceive naturally, this treatment is a very safe and effective method of becoming pregnant and having a child," adds Dr. Dayan, who is also an Assistant Professor in the Department of Medicine, Division of General Internal Medicine at McGill’s Faculty of Medicine.

In Canada, one in six couples is affected by infertility and many turn to assisted reproductive technology. As a result, these treatments result in approximately 18,000 births in Canada each year. Fertility experts in Ontario have recently generated data to not only evaluate the success rate of these treatments, but also to conduct appropriate surveillance of the mother's health after treatment.

The researchers looked at this data from 813,719 births in Ontario hospitals between 2006 and 2012. They identified 11,546 women who conceived through infertility treatment and matched them with 47,553 women with similar characteristics who conceived without any assistance. Women who conceive with infertility treatments are typically older, are more often first-time mothers or pregnant with twins than are women who conceive ‘naturally,’ and these characteristics often mean a high-risk pregnancy.

Although the study, published in the CMAJ, does suggest a small added risk from the treatment itself, the authors note that "[w]hether specific components of treatment using in vitro fertilization, such as the dose of ovarian hyperstimulation or fresh versus frozen embryo transfer, contribute to these complications, or whether the increased risk is a reflection of a typical woman who requires or choose in vitro fertilization, remains to be determined." An interesting finding is that the higher risk of one of these pregnancy complications was found among recipients of in vitro fertilization, but not among those who received other types of infertility treatments, such as intrauterine insemination or ovulation induction with medication.

In recent years, the medical and scientific community has emphasized the importance of optimal maternal health before infertility treatment. Fertility specialists often consult with other experts to ensure good control of any health conditions before pregnancy, and often choose to implant only one embryo per mother to avoid risks associated with twin or triplet pregnancies.

When asked what women and their practitioners should do with this information, senior author Joel Ray, researcher at ICES and the Li Ka Shing Knowledge Institute of St. Michael's Hospital, said “The first step is to monitor women for such side effects. Women who are felt to be at higher risk should be informed about these small but important health risks. If infertility treatment is chosen by the patient and her doctor, she may need to be followed more closely during pregnancy by obstetricians and medical specialists with experience in high-risk pregnancies.”

The researchers add that future planned studies will look more closely at the factors that led to these pregnancy complications, with the eventual goal of allowing physicians to further customize treatments to each individual woman who seeks reproductive assistance, to optimize the chance of a successful and healthy pregnancy.


The article “Infertility treatment and risk of severe maternal morbidity: a propensity score matched cohort study,” by Natalie Dayan et al. is published in the February 4, 2019 issue of CMAJ.

This work was funded by the Canadian Institutes of Health Research (CIHR).

ICES is an independent, non-profit research institute that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy. In October 2018, the institute formerly known as the Institute for Clinical Evaluative Sciences formally adopted the initialism ICES as its official name. For the latest ICES news, follow us on Twitter: @ICESOntario

The Research Institute of the McGill University Health Centre (RI-MUHC) is a world-renowned biomedical and healthcare research centre. The Institute, which is affiliated with the Faculty of Medicine of McGill University, is the research arm of the McGill University Health Centre (MUHC) – an academic health centre located in Montreal, Canada, that has a mandate to focus on complex care within its community. The RI-MUHC supports over 460 researchers and close to 1,300 research trainees devoted to a broad spectrum of fundamental, clinical and health outcomes research at the Glen and the Montreal General Hospital sites of the MUHC. Its research facilities offer a dynamic multidisciplinary environment that fosters collaboration and leverages discovery aimed at improving the health of individual patients across their lifespan. The RI-MUHC is supported in part by the Fonds de recherche du Québec – Santé (FRQS).

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