Early- and Late-Onset Preeclampsia: 2 Different Entities?

Steven Fox

August 29, 2013

Early- and late-onset preeclampsia share some etiologic features, but their risk factors differ, and they often lead to different outcomes, according to a study published online August 26 in the American Journal of Obstetrics and Gynecology.

"The two pre-eclampsia types should be treated as distinct entities from an etiologic and prognostic standpoint," write Sarka Lisonkova, MD, PhD, from the Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, Canada, and K.S. Joseph, MD, PhD, also from the university's Department of Obstetrics and Gynecology and its School of Population and Public Health.

The authors note that the population-based incidence of early-onset preeclampsia (<34 weeks' gestation) and late-onset preeclampsia (≥34 weeks' gestation) has not been fully studied.

Therefore, the researchers analyzed the incidence of preeclampsia, using gestational-age onset, and identified risk factors and birth outcomes associated with those varying clinical presentations.

They used hospital records and birth certificate databases to identify all singleton deliveries that occurred in Washington state between 2003 and 2008..They estimated adjusted hazard ratios for risk factors and adjusted odds ratios (AORs) for birth outcomes, using Cox and logical regression models.

Among 456,668 births assessed, the overall preeclampsia rate was 3.1%, and the incidence increased sharply as gestation progressed.

The rate for early-onset preeclampsia was 0.38% compared with 2.72% for late-onset preeclampsia.

Early- and late-onset preeclampsia share some risk factors, including older maternal age, Hispanic race, Native American race, smoking, unmarried status, and male fetus. Several risk factors were more strongly associated with early-onset preeclampsia than late-onset disease, including black race, chronic hypertension, and congenital anomalies. were more strongly associated with early-onset preeclampsia. In contrast, younger maternal age, nulliparity, and diabetes mellitus were more strongly associated with late-onset preeclampsia than with early-onset disease.

In addition, early-onset preeclampsia was significantly associated with a high risk for fetal death (AOR, 5.8; 95% confidence interval [CI], 4.0 - 8.3), but late-onset preeclampsia was not (AOR, 1.3; 95% CI, 0.8 - 2.0).

However, the AOR for perinatal death/severe neonatal morbidity was significant for both early-onset (16.4; 95% CI, 14.5 - 18.6) and late-onset (2.0; 95% CI, 1.8 - 2.3) preeclampsia.

"Our study thus confirms the heterogeneity of pre-eclampsia and shows that the timing of disease onset is one important indicator of disease severity and possibly of disease etiology," the researchers conclude. "Research studies should treat the two pre-eclampsia sub-types as distinct entities from an etiologic and prognostic standpoint."

This study was supported by the Canadian Institutes of Health Research. The authors have disclosed no relevant financial relationships.

Am J Obstet Gynecol. Published online August 26, 2013. Abstract


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