Gestational hypertension in pregnancies supported by infertility treatments: role of infertility, treatments, and multiple gestations.

OBJECTIVE: To investigate the association between infertility treatments and gestational hypertension and preeclampsia.
DESIGN: Retrospective observational cohort.
SETTING: General population, United States and Canada. PATIENT(S): Five thousand one hundred fifty-one women with non-malformed infants participating in the Slone Epidemiology Center Birth Defects Study between 1998 and 2006. INTERVENTION(S): Women were interviewed within 6 months after delivery about sociodemographic and medical factors, about the onset of gestational hypertension and preeclampsia, and about infertility treatments. MAIN OUTCOME MEASURE(S): We estimated relative risks and 95% confidence intervals by using unconditional logistic regression. RESULT(S): The incidence of gestational hypertension was 8.9% (423/4,762) among women without infertility treatments and was 15.8% (55/349) among women undergoing infertility treatments. Compared with spontaneous pregnancies, the crude relative risk for gestational hypertension in pregnancies resulting from infertility treatments was 1.9 (95% confidence interval, 1.4-2.6). Multivariate adjustment for parity and prepregnancy body mass index resulted in a relative risk of 1.6 (1.1-2.1). Further adjustment for multiple pregnancies, or restriction of the analyses to singleton pregnancies, moved the relative risk to 1.3. Each specific infertility procedure or drug was associated with a similarly elevated risk, which disappeared after adjustment for multiple gestations. Results were similar for preeclampsia. CONCLUSION(S): Pregnancies resulting from infertility treatments have a higher incidence of gestational hypertension and preeclampsia than do spontaneous conceptions. This increased risk is largely explained by the higher frequency of multiple gestations.