Incidence and Predictors of Severe Obstetric Morbidity: Case-Control Study

Abstract

Records at 25 maternity units in London covering a 1-year period during 1997-1998 were reviewed to determine the frequency of severe obstetrical morbidity and to identify predictors. The study population of 48,865 women delivering infants during this period included 588 who met criteria for severe obstetrical morbidity. Four conditions were considered: severe bleeding; severe preeclampsia, including hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome and eclampsia; severe sepsis: and uterine rupture. Four control subjects were chosen for each case subject to better detect differences in predictive factors. The incidence of severe obstetrical morbidity in this review was 12 per 1000 deliveries (95% confidence interval, 11.2-13.2). Five maternal deaths were ascribed directly to the study conditions: three to sepsis and one each to bleeding and HELLP syndrome. The ratio of severe morbidity to mortality was 118:1. Disease-specific morbidity rates per 1000 deliveries were 6.7 for severe hemorrhage, 3.9 for severe preeclampsia, ().2 for eclampsia, 0.5 for HELLP syndrome. 0.4 for severe sepsis, and 0.2 for uterine rupture. After adjustment for confounding factors, characteristics independently associated with severe obstetrical morbidity as a whole included age greater than 34 years, nonwhite ethnicity, past or current hypertension, previous postpartum bleeding, emergency cesarean delivery, antenatal hospital admission, multiple pregnancy, and taking iron or an antidepressant before delivery. Few risk factors were independently and significantly associated with the occurrence of severe sepsis or uterine rupture. These findings suggest that severe obstetrical morbidity may be a more sensitive measure of pregnancy outcomes than mortality by itself. Most of these events are related to obstetrical bleeding and severe preeclampsia, and lowering the risk will require attention to the best ways of managing these complications.