Importance: Maternal labor epidural analgesia (LEA) and oxytocin use for labor and delivery have been reported to be associated with child autism spectrum disorders (ASD). However, it remains unclear whether these 2 common medications used during labor and delivery have synergistic associations with ASD risk in children.
Objective: To assess the independent associations of LEA and oxytocin during labor and delivery with ASD, as well as outcome modification associated with the concurrent use of both interventions.
Design, setting, and participants: Data for this cohort study included 205 994 singleton births with vaginal deliveries in a single integrated health care system in Southern California from calendar years 2008 to 2017. Children were followed up to December 31, 2021. Data on use of LEA and oxytocin, covariates, and ASD outcome in children were obtained from electronic medical records. Cox proportional hazards regression was used to estimate the hazard ratios (HRs) adjusting for covariates.
Exposures: Labor epidural analgesia and/or oxytocin use during labor and delivery.
Main outcomes and measures: A child's clinical diagnosis of ASD during follow-up and at age of diagnosis.
Results: Among the cohort, 153 880 children (74.7%) were exposed to maternal LEA and 117 808 children (57.2%) were exposed to oxytocin during labor and delivery. The population of children was approximately half boys and half girls. The median (IQR) age of the mothers was 30.8 (26.8-34.5) years for those not exposed to LEA, 30.0 (25.9-33.8) years for those exposed to LEA, 30.4 (26.5-34.1) years for those unexposed to oxytocin, and 30.0 (25.9-33.9) years for those exposed to oxytocin during labor and delivery. A total of 5146 children (2.5%) had ASD diagnosed during follow-up. Oxytocin exposure was higher among LEA-exposed (67.7%) than -unexposed (26.1%) children. The ASD risk associated with LEA was independent of oxytocin exposure (HR, 1.28; 95% CI, 1.18-1.38); however, the ASD risk associated with oxytocin was not significant after adjusting for LEA exposure (HR, 1.05; 95% CI, 0.99-1.12). A significant interaction of LEA and oxytocin on child ASD risk was found (P = .02 for interaction). Compared with no exposure, HRs were 1.20 (95% CI, 1.09-1.32) for LEA alone, 1.30 (95% CI, 1.20-1.42) for both LEA and oxytocin, and 0.90 (95% CI, 0.78-1.04) for oxytocin alone.
Conclusions and relevance: The findings of this cohort study suggest an association between maternal LEA and ASD risk in children, and the risk appeared to be further increased if oxytocin was also administered. Oxytocin exposure without LEA exposure was not associated with ASD risk in children. These findings must be interpreted with caution. Further studies are needed to replicate or refute the study results and examine biological plausibility.