Late preterm and early term: when to induce a growth restricted fetus? A population-based study.

Purpose: (1) Compare fetal and neonatal morbidity and mortality associated with induction of labor (IOL) versus expectant management (EM) in women with isolated fetal growth restriction (FGR) between 34(0/7) and 38(6/7) weeks; (2) Determine optimal gestational age for delivery of such fetuses. Materials and methods: A retrospective population based cohort study of 2232 parturients with isolated FGR, including two groups: (1) IOL (n = 1428); 2) EM (n = 804). Results: IOL group had a lower stillbirth and neonatal death rates (p =.042, p < .001), higher 1 and 5 min Apgar scores and a higher vaginal delivery rate compared to the EM group. In the late preterm period, EM was associated with increased rate of low 1 and 5 min Apgar scores, nonreassuring fetal heart rate tracing (NRFHR), stillbirth and neonatal death rate (p = .001, p = .039). In the early term cohort, EM was associated with a higher rate of NRFHR and low 1 min Apgar scores (p = .003, p = .002). IOL at 37 weeks protected from stillbirth but not from adverse composite neonatal outcomes. Conclusions: IOL of FGR fetuses at 37 weeks had a protective effect against stillbirth. In addition, at late preterm, it is associated with lower rates of stillbirth, neonatal death, and NRFHR.