Association of Induced and/or Augmented Labor with Autism Spectrum Disorder in a Gestational Age-Stratified Utah Cohort

Background: One in 68 children in the U.S. is diagnosed with autism spectrum disorder (ASD). Previous research suggests that environmental factors during childbirth, including induction and/or augmentation of labor, may contribute to risk of ASD diagnosis in childhood.  This association may be modified by gestational age at the time of exposure.

Objectives: Our objective is to evaluate whether induced and/or augmented labor is associated with increased odds of ASD in a gestational age-stratified Utah cohort.

Methods: We performed an epidemiological analysis using data from the Utah Registry of Autism and Developmental Disabilities (URADD) and the Utah Department of Health (UDOH) Office of Vital Records and Statistics. URADD ascertains children with ASD within a three county surveillance area (approximately 70% of the Utah population) by querying records from UDOH, clinics, hospitals and behavioral health centers. Children met the URADD case definition of ASD if they acquired an ASD diagnosis from a qualified health provider such as a developmental pediatrician, child psychiatrist, or clinical psychologist. Selection of cases and controls was limited to children born to mothers between the ages of 15 and 49 years, infants weighing at least 400 grams at delivery, infants born between 24 and 42 weeks’ gestation, infants without congenital anomalies, and infants born in the three county URADD surveillance area. The control group included all children not identified with ASD who met inclusion criteria. The resulting study sample was composed of 2219 children identified with ASD (case group) and 166,361 children without ASD (control group) belonging to the 1998, 2000, 2002, 2004, and 2006 birth cohorts ascertained by URADD. Birth certificates contained exposure to labor induction and/or augmentation as well as known ASD risk factors, which were treated as confounders in this analysis. Multiple imputation was conducted for missing interval and ratio-scale birth certificate covariate data. Differences in characteristics between cases and controls were examined using chi-square goodness-of-fit tests. Single and multiple logistic regression models examined the probability of being an ASD case or control as related to labor induction and/or augmentation, adjusting for confounders.  The models were then stratified by established gestational age subgroups.

Results: Approximately 1 in 66 children in the cohort had ASD. Compared with children not exposed to labor induction and/or augmentation, children exposed to induction and augmentation, induction only, or augmentation only, did not have increased odds of ASD after controlling for potential confounders related to socioeconomic status, maternal health, pregnancy-related events and conditions, and birth cohort. The gestational age stratified analyses yielded similar results. (Table)

Conclusions: Induction and/or augmentation during childbirth are not associated with increased odds of ASD in childhood in a large gestational age-stratified Utah cohort.