History of abortion and subsequent risk of preeclampsia

OBJECTIVE: To examine the effect of abortion type, number and timing on risk of preeclampsia in subsequent pregnancies. STUDY DESIGN: We conducted a hospital-based, case-control study in Seattle and Tacoma, Washington, between 1998 and 2001. Preeclampsia cases (n = 199) and controls (n = 383) provided detailed information regarding their pregnancy histories and other covariates, such as prepregnancy weight and adult height. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. RESULTS: Multiparous women, both with a history of abortion and without, experienced decreases of 60% (adjusted OR = 0.40, 95% CI .23-.71) and 71% (adjusted OR = .29, 95% CI .16-.53), respectively, in risk of preeclampsia when compared to nulliparous women with no history of abortion. Type (spontaneous and/or induced), number and timing of prior abortion did not appear to influence the risk of preeclampsia among nulliparous women. CONCLUSION: These results confirm the work of others that multiparous women, both with and without a history of abortion, have a reduced risk of preeclampsia. However, much work remains with respect to exploring mechanistic hypotheses offering biologic explanations and examining possible confounding factors of this association, such as change in paternity and interpregnancy interval.