Mode of delivery for confirmed macrosomia: a real-life multicentric observational study.

INTRODUCTION

Macrosomia, defined as a birth weight exceeding 4,000 grams, is an increasing concern in obstetric practice due to its associated delivery risks. Early induction of labor for large-for-gestational-age fetuses has been proposed to reduce shoulder dystocia and birth trauma, but the impact on maternal outcomes remains controversial.

METHODS

This retrospective multicenter study was conducted across three French university hospitals over a five-year period (2017–2023). Included were women with singleton term deliveries (≥37 weeks) and confirmed birth weight >4,000 g. Women with more than one previous cesarean, multiple pregnancy, breech presentation, or medical indications for elective cesarean were excluded. Labor induction was performed according to local DAME-based protocols. Patients were admitted either the morning of or the day before induction. For a Bishop score <6, cervical ripening was proposed using prostaglandins, oral misoprostol, or a double-balloon catheter, with method selection based on patient preference. For a Bishop score ≥6, induction of contractions was initiated using prostaglandins. The primary outcome was mode of delivery; secondary outcomes included postpartum hemorrhage (PPH), perineal injury, and neonatal morbidity (Apgar score, cord pH, shoulder dystocia). Analyses were adjusted for maternal age, pre-pregnancy BMI, parity, diabetes, and birth weight.

RESULTS

Among 76,375 deliveries, 4,300 met inclusion criteria (1,794 inductions and 2,496 spontaneous labors). Induction was associated with higher cesarean rates (45% vs. 10%; adjusted OR 2.43 [1.42–4.17] at 38 weeks and 1.85 [1.24–2.78] at 39 weeks) and increased PPH (27% vs. 15%; adjusted OR 1.82 [1.17–2.84] and 1.51 [1.08–2.11], respectively). Multiparity was protective, while each BMI unit increased cesarean risk by 6%. No significant differences were observed in Apgar <7, shoulder dystocia, or neonatal pH. Results were consistent in sensitivity analyses using ≥90th and ≥95th percentile thresholds.

CONCLUSIONS

In confirmed macrosomia, labor induction was associated with increased cesarean delivery and postpartum hemorrhage without neonatal benefit. These findings highlight the need for cautious, individualized decision-making and improved accuracy of prenatal fetal weight estimation to reduce unnecessary inductions. TRIAL REGISTRATION: The study was declared to CNIL: 23-5317 and registered on ClinicalTrials.gov: NCT06198881. (Registration date: January 10, 2024).