In women with late preterm preeclampsia, the optimal time for delivery remains a controversial topic, because of the fine balance between the maternal benefits from early delivery and the risks for prematurity. It remains challenging to define prognostic markers to identify women at highest risk for complications, in which case a selective, planned delivery may reduce the adverse maternal and perinatal outcomes.

This trial aimed to determine whether using an algorithm based on the maternal levels of placental growth factor in women with late preterm preeclampsia to evaluate the best time for delivery reduced the progression to preeclampsia with severe features without increasing the adverse perinatal outcomes.

This parallel-group, open-label, multicenter, randomized controlled trial was conducted at 7 maternity units across Spain. We compared selective planned deliveries based on maternal levels of placental growth factor at admission (revealed group) and expectant management under usual care (concealed group) with individual randomization in singleton pregnancies with late preterm preeclampsia from 34 to 36+6 weeks’ gestation. The coprimary maternal outcome was the progression to preeclampsia with severe features. The coprimary neonatal outcome was morbidity at infant hospital discharge with a noninferiority hypothesis (noninferiority margin of 10% difference in incidence). Analyses were conducted according to intention-to-treat.

Between January 1, 2016, and December 31, 2019, 178 women were recruited. Of those women, 88 were assigned to the revealed group and 90 were assigned to the concealed group. The data analysis was performed before the completion of the required sample size. The proportion of women with progression to preeclampsia with severe features was significantly lower in the revealed group than in the concealed group (adjusted relative risk, 0.5; 95% confidence interval, 0.33–0.76; P=.001). The proportion of infants with neonatal morbidity was not significantly different between groups (adjusted relative risk, 0.77; 95% confidence interval, 0.39–1.53; P=.45).

There is evidence to suggest that the use of an algorithm based on placental growth factor levels in women with late preterm preeclampsia leads to a lower rate of progression to preeclampsia with severe features and reduces maternal complications without worsening the neonatal outcomes. This trade-off should be discussed with women with late preterm preeclampsia to allow shared decision making about the timing of delivery.