PREECLAMPSIA - A NESTED, CASE-CONTROL STUDY OF RISK-FACTORS AND THEIRINTERACTIONS

OBJECTIVE: To study the risk factors for preeclampsia and their intera ctions. STUDY DESIGN: We used a nested, case-control study design to a nalyze data collected in the Delivery Interview Program, 1977-1980, Bo ston Hospital for Women (now known as the Brigham and Women's Hospital ), Boston. Cases (n=386) of obstetrician-diagnosed preeclampsia were c ompared with randomly selected controls (n=2,355). Using multiple logi stic regression, we derived maximum likelihood estimates of adjusted o dds ratios (ORs) and 95% confidence intervals (Cls). RESULTS: The foll owing risk factors were statistically significantly associated with pr eeclampsia: urinary tract infection (UTI) during pregnancy (OR 1.6, 95 % CI 1.1-2.5), primiparity (OR 3.8, 95% CI 2.8-5.2), black race (OR 1. 5, 95% CI 1.1-1.9), less than a high school education (PX 2.0, 95% CI 1.1-3.6), exposure to diethylstilbestrol in utero (OX 2.4, 95% CI 1.2- 2.4), body mass index (kg/m(2)) >30 (OX 2.7, 95% CI 1.6-4.4) and cigar ette smoking (OA 0.6, 95% CI 0.5-0.8). When evaluating interactions be tween variables, we found that primiparas who had UTI during pregnancy were five times more likely (OX 5.3, 95% CI 2.9-9.7) to have preeclam psia than were primiparas who did not have UTI during pregnancy. CONCL USION: It is possible that the preeclampsia associated with some of th e risk factors we identified could be modified by the use of prophylac tic drugs or other interventions. The primipara with a UTI would be a most likely beneficiary.