Maternal Autistic Traits and Adverse Birth Outcomes.

Importance: Women with a high level of autistic traits in the general population may experience larger health disparities during pregnancy, particularly women diagnosed with autism spectrum disorder (ASD), which in turn may be associated with increased risk of adverse birth outcomes. Objective: To investigate the association between maternal autistic traits and the risk of adverse birth outcomes in the general population. Design, Setting, and Participants: This cohort study included mothers of singletons from a nationwide, multicenter prospective birth cohort, the Japan Environmental Children's Study. Expecting mothers were recruited between January 2011 and March 2014. Data were analyzed between June 2021 and November 2023. Exposures: Autistic traits were self-reported during the second and third trimesters using the short form of the Autism-Spectrum Quotient Japanese version (AQ-J10) (score range, 0-10; clinical range, ≥7). Main Outcomes and Measures: Data on preterm birth (<37 weeks' gestation) and neonates born small for gestational age (SGA) were transcribed from medical records. Additional analysis of gestational age groups (very preterm birth, <32 weeks' gestation; moderate-to-late preterm birth, 32-36 weeks' gestation) was also performed. Results: Among 87 687 women (mean [SD] age, 31.2 [5.0] years) included in the study, 2350 (2.7%) had AQ-J10 scores within the clinical range yet only 18 (0.02%) were diagnosed with ASD. A higher AQ-J10 score was associated with an increased risk of all birth outcomes, including preterm births (relative risk [RR] per 1-SD increase, 1.06; 95% CI, 1.03-1.09), moderate-to-late preterm births (RR per 1-SD increase, 1.05; 95% CI, 1.01-1.08), very preterm births (RR per 1-SD increase, 1.16; 95% CI, 1.06-1.26), and child born SGA (RR per 1-SD increase, 1.04; 95% CI, 1.01-1.06) after adjusting for maternal and pregnancy-related factors. The risks of all outcomes increased with higher AQ-J10 scores; compared with women below the clinical range, women within the clinical range had greater risk of preterm births (RR, 1.16; 95% CI, 1.07-1.26), moderate-to-late preterm births (RR, 1.12; 95% CI, 1.03-1.22), very preterm births (RR, 1.49; 95% CI, 1.18-1.89), and a child born SGA (RR, 1.11; 95% CI, 1.04-1.19). Conclusions and Relevance: In this cohort study, higher level of maternal autistic traits was associated with increased risk of adverse birth outcomes, particularly very preterm birth. Acknowledging the risks and providing tailored and timely antenatal care support to women with a high level of autistic traits in the general population, particularly women with autistic traits within the clinical range, regardless of formal diagnosis, is warranted.