Timing of induction of labor in suspected macrosomia: retrospective cohort study, systematic review and meta-analysis.

OBJECTIVE: Large-for-gestational-age (LGA) is associated with several adverse maternal and neonatal outcomes. Although many studies have found that early induction of labor (eIOL) in LGA reduces the incidence of shoulder dystocia (SD), no current guidelines recommend this particular strategy, due to concerns about increased rates of cesarean delivery (CD) and neonatal complications. The purpose of this study was to assess whether the timing of IOL in LGA fetuses affects maternal and neonatal outcomes in a single center; and to combine these results with the evidence reported in the literature.

METHODS: This study comprised two parts. The first was a retrospective cohort study that included: consecutive patients with singleton pregnancy, an estimated fetal weight (EFW) ≥90th percentile on ultrasound (US) between 35+0 and 39+0 weeks of gestation (WG), who were eligible for normal vaginal delivery. The second part was a systematic review of literature and meta-analysis that included the results of the first part as well as all previously reported studies that have compared IOL to expectant management in patients with LGA. The perinatal outcomes were CD, operative vaginal delivery (OVD), SD, brachial plexus palsy, anal sphincter injury, postpartum hemorrhage (PPH), APGAR score, umbilical arterial pH, neonatal intensive care unit (NICU) admission, use of continuous positive airway pressure (CPAP), intracranial hemorrhage (ICH), phototherapy, and bone fracture.

RESULTS: Retrospective cohort: of the 547 patients, 329 (60.1%) were induced and 218 (39.9%) entered spontaneous labor. Following covariate balancing, CD was significantly higher in the IOL group in comparison to the spontaneous labor group. This difference only became apparent beyond 40WG (hazard ratio: 1.9, p=0.030). The difference between both groups for shoulder dystocia was not statistically significant. Systematic review and metanalysis: 17 studies were included in addition to our own results giving a total sample size of 111,300 participants. When IOL was performed <40+0WG, the risk for SD was significantly lower in the IOL group (OR: 0.64, 95%CI: 0.42-0.98, I2 =19%). There was no significant difference in CD rate between IOL and expectant management after pooling the results of these 17 studies. However, when removing the studies in which IOL was done exclusively before 40+0WG, the risk for CD in the remaining studies (IOL not exclusively <40+0WG) was significantly higher in the IOL group (odds ratio [OR]: 1.46, 95% confidence interval [95%CI]: 1.02-2.09, I2 =56%). There were no statistically significant differences between IOL and expectant management for the remaining perinatal outcomes. Nulliparity, history of CD, and low Bishop score but not methods of induction were independent risk factors for intrapartum CD in patients who were induced for LGA.

CONCLUSION: Timing of IOL in patients with suspected macrosomia significantly impacts perinatal adverse outcomes. IOL has no impact on rates of SD but does increase CD when considered irrespective of gestational age, but it may decrease the risk of SD without increasing the risk of other adverse maternal outcomes, in particular cesarean section when performed before 40+0 WG. (GRADE: Low/Very low). This article is protected by copyright. All rights reserved.