In vitro fertilization and risk for hypertensive disorders of pregnancy: associations with treatment parameters.

backgroundAlthough in vitro fertilization has been associated with an increased risk for hypertensive disorders of pregnancy, the association of risk with in vitro fertilization treatment parameters is unclear.

objectiveTo evaluate risk for hypertensive disorders of pregnancy by maternal fertility status and in vitro fertilization treatment parameters. MATERIALS AND

methodsWomen in 8 states who underwent in vitro fertilization resulting in a live birth during 2004-2013 were linked to their infant's birth certificates. A 10:1 sample of births from non-in vitro fertilization deliveries were selected for comparison. Those with an indication of infertility treatment on the birth certificate were categorized as subfertile and omitted from the study population; all others were categorized as fertile. The in vitro fertilization pregnancies were additionally categorized by oocyte source (autologous versus donor) and embryo state (fresh versus thawed). Both the fertile and in vitro fertilization births were limited to singletons only, and the in vitro fertilization pregnancies were limited to those using partner sperm. Hypertensive disorders of pregnancy (including gestational hypertension and preeclampsia) were identified from the birth certificate, modeled using logistic regression, and reported as adjusted odds ratios and 95% confidence intervals. For analyses of in vitro fertilization pregnancies from autologous oocytes-fresh embryos, the reference group was fertile women (subgroup analysis 1). For analyses within the in vitro fertilization group, the reference group was autologous oocytes-fresh embryos (subgroup analysis 2).

resultsThe study population included 1,465,893 pregnancies (1,382,311 births to fertile women and 83,582 births to in vitro fertilization-treated women). Compared to fertile women, in vitro fertilization-treated women with autologous-fresh cycles were not at increased risk for hypertensive disorders of pregnancy (adjusted odds ratio, 1.04; 95% confidence interval, 0.99, 1.08). Among in vitro fertilization births (subgroup analysis 2), the risk for hypertensive disorders of pregnancy was increased for the autologous-thawed (adjusted odds ratio, 1.30; 95% confidence interval, 1.20, 1.40); donor-fresh (adjusted oddds ratio, 1.92; 95% confidence interval, 1.71, 2.15); and donor-thawed (adjusted odds ratio, 1.70; 95% confidence interval, 1.47, 1.96) groups. Excluding women with pregestational diabetes or chronic hypertension as well as adjusting for body mass index and infertility diagnoses did not substantially change the results. When stratified by <34 weeks (early-onset hypertensive disorders of pregnancy) versus ≥34 weeks (late-onset hypertensive disorders of pregnancy), only the donor-fresh group had an increased risk of early-onset hypertensive disorders of pregnancy, but the risks for all other oocyte source-embryo state groups compared to autologous-fresh were increased for late-onset hypertensive disorders of pregnancy.

conclusionThe risk for hypertensive disorders of pregnancy is increased for in vitro fertilization-treated women in pregnancies conceived via frozen embryo transfer (with both autologous or donor oocyte) and fresh donor oocyte embryo transfer. No increase in risk was seen with autologous oocyte-fresh embryo transfers in vitro fertilization cycles. Excluding women with pregestational diabetes or chronic hypertension as well as adjusting for body mass index and infertility diagnoses did not substantially change the results.