Planned mode of delivery and neonatal outcomes in pregnancies complicated by late-onset fetal growth restriction: a retrospective cohort study.

BACKGROUND

Fetal growth restriction (FGR) is a major contributor to perinatal morbidity and mortality. While guidelines address timing of delivery, the optimal mode-induction of labor (IOL) versus planned cesarean delivery (CD)-remains uncertain.

OBJECTIVE

To evaluate the association between planned mode of delivery and neonatal outcomes in pregnancies complicated by late onset FGR (LOFGR).

STUDY

DESIGN

We conducted a retrospective cohort study at a tertiary Canadian center (2017-2022). Singleton pregnancies with LOFGR (> 34 weeks' gestation), defined by Society for Maternal-Fetal Medicine (SMFM) criteria, were eligible if the last ultrasound was within 14 days of delivery. Exclusions included spontaneous labor, delivery < 34 weeks, and contraindications to labor. Planned mode of delivery (IOL vs CD) was the exposure. Outcomes were classified as severe (perinatal death, 5-min Apgar < 4, umbilical arterial pH < 7.05, base deficit ≥ 12 mmol/L, hypoxic-ischemic encephalopathy/therapeutic hypothermia, grade III-IV intraventricular hemorrhage, necrotizing enterocolitis, sepsis, or invasive ventilation > 24 h) or moderate (NICU stay > 72 h, Apgar 4-6, pH 7.05-7.10, non-invasive respiratory support > 6-12 h, transient tachypnea, or brief resuscitation). Multivariable logistic regression adjusted for confounders. A prespecified subgroup applied the ISUOG criteria.

RESULTS

Of 12,270 deliveries, 1,143 (9.3%) met SMFM criteria for LOFGR; 869 were eligible (192 planned CD, 677 IOL). Severe outcomes and moderate outcomes were more frequent after CD (23.4% vs 16.7%; p = 0.03 and 42.2% vs 31.2%; p < 0.01, respectively). IOL was associated with lower adjusted risk of severe outcomes (aOR 0.35; 95% CI 0.19-0.67) and moderate outcomes (aOR 0.43; 95% CI 0.24-0.76). Results were consistent using ISUOG criteria (aOR 0.33; 95% CI 0.17-0.62 and aOR 0.44; 95% CI 0.25-0.79, respectively) About 20% of induced patients required intrapartum CD.

CONCLUSIONS

IOL was associated with reduced severe and moderate neonatal morbidity compared with planned CD. IOL represents a safe alternative when intrapartum surveillance and timely operative delivery are available.