Preeclampsia as a cause of preterm and late preterm (near-term) births.

Gestational hypertension-preeclampsia is the most common medical disorder of pregnancy. It is also a major cause of maternal and perinatal morbidities. The majority of adverse pregnancy outcomes occur in patients who develop severe hypertension or severe preeclampsia, and in those who develop the clinical manifestations before 34 weeks' gestation. There is some concern regarding neonatal morbidity in the late preterm (near term) infant (34 0/7 through 36 6/7 weeks' gestation) as a result of gestational hypertension and preeclampsia. A review of the available data suggests that most deliveries of the late preterm infant in such women are justified because of the concerns about maternal and fetal safety with continued gestation. In addition, the rate of preterm delivery at 34 to 36 weeks' gestation in women with gestational hypertension or preeclampsia is low. Indeed, most admissions to Neonatal Intensive Care Unit in such pregnancies occur in those at > or =37 weeks' gestation. There is urgent need for research to assess the reasons behind preterm delivery at 34 to 36 weeks' gestation in women with hypertension and preeclampsia. In addition, there is need for research to assess the reasons for admission to the NICU in term infants born of mothers with varying severities of hypertension and preeclampsia. In this paper, the phrase "late-preterm" has been used instead of "near term," as the former was considered more appropriate to reflect this subgroup of preterm infants in a workshop on this topic held in July 2005, organized by the National Institute of Child Health and Human Development.