Importance: Intellectual and developmental disabilities (IDDs) include cognitive and adaptive deficits beginning before ages 18 to 22 years. People with IDDs experience disparities in pregnancy and infant outcomes, yet little is known about how risks differ across IDD subtypes or the extent to which associated maternal health conditions contribute to these disparities. Objectives: To evaluate the associations between maternal IDD subtypes and adverse infant outcomes and to estimate how much these associations may be explained by modifiable maternal health conditions. Design, Setting, and Participants: This cohort study analyzed births in California from January 1, 2007, to December 31, 2021, using data from the Study of Outcomes in Mothers and Infants, which links vital statistics on births and infant deaths with maternal and infant hospital inpatient and emergency department records. All 6 435 742 singleton births with gestation between 22 and 44 weeks were included. Statistical analyses were completed on February 19, 2026. Exposures: Maternal IDD diagnoses, including autism spectrum disorder, cerebral palsy, intellectual disability, chromosomal differences, and other IDDs (eg, fetal alcohol syndrome, tuberous sclerosis, and congenital malformations), were identified from hospital records. Potential mediators included prenatal care utilization, prenatal tobacco use, preexisting chronic and neuropsychiatric conditions, and body mass index. Main Outcomes and Measures: Outcomes included neonatal intensive care unit (NICU) admission, small-for-gestational-age (SGA) birth, preterm birth (PTB) at less than 37 weeks, and very PTB at less than 32 weeks. Results: Of 6 435 742 singleton births, 4492 were to mothers with IDD diagnoses (mean SD maternal age at birth: IDD cohort, 29 7 years; overall cohort, 30 6 years). Infants born to mothers with IDD had higher risks of NICU admission (14% 628 of 4492 vs 5% 327 345 of 6 426 048; adjusted risk ratio ARR, 2.76 95% CI, 2.56-2.98), SGA birth (14% 614 of 4492 vs 9% 569 146 of 6 426 048; ARR, 1.56 95% CI, 1.44-1.68), PTB (16% 717 of 4492 vs 7% 452 177 of 6 426 048; ARR, 2.34 95% CI, 2.18-2.51), and very PTB (3% 122 of 4492 vs 1% 62 290 of 6 426 048; ARR, 3.20 95% CI, 2.66-3.86) compared with infants born to mothers without IDD. Risks were highest for maternal diagnoses of chromosomal differences, other IDDs, and intellectual disability. Preexisting hypertension, epilepsy, and mental health conditions were associated with a substantial portion of the risk, particularly for NICU admission. Conclusions and Relevance: In this cohort study of births in California, pregnant people with IDD diagnoses had substantially higher risks of adverse infant outcomes. Preexisting hypertension and neuropsychiatric conditions were key variables and may represent modifiable targets for preconception and prenatal intervention.
Psaras et al. (Wed,) studied this question.