Subfecundity, Infertility Treatment, and Child Neurodevelopment

Importance: Increasing numbers of children are conceived using infertility treatment; concerns remain about potential effects on child neurodevelopment. Objective: To evaluate whether infertility treatment is associated with child neurodevelopment and whether such an association may be attributable to underlying subfecundity. Design, Setting, and Participants: This cohort study was conducted among mother-child dyads in the National Institutes of Health Environmental Influences on Child Health Outcomes Cohort, with infants conceived between 1998 and 2022. Associations of subfecundity and infertility treatment with neurodevelopmental outcomes were assessed among children ages 2 to 10 years. Data were analyzed from May 14, 2025, to March 31, 2026. Exposure: Subfecundity was defined as prior consultation for, treatment of, or diagnosis of infertility for either partner; at least 2 prior miscarriages; or ever having had unprotected heterosexual intercourse for 12 months without conceiving. Infertility treatment was categorized as in vitro fertilization (IVF) or non-IVF treatment. Main Outcomes and Measures: Harmonized caregiver responses to the Strengths and Difficulties Questionnaire and the Child Behavior Checklist yielded continuous raw scores for externalizing and internalizing problems. The total raw Social Responsiveness Scale (SRS) score quantified autism-like symptoms. Caregivers reported physician diagnosis of autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD). Results: Among 15 382 mother-infant dyads, there were 14 191 unique maternal participants (mean [SD] age at delivery, 30.9 [5.33] years; 8780 parous participants [57.1%]). ASD and ADHD were diagnosed in 876 offspring (7.6%) and 819 offspring (7.1%), respectively. In generalized linear models, subfecundity was associated with higher externalizing problem and SRS scores among all pregnancies (externalizing problems: b = 0.47 [95% CI, 0.14-0.81]; SRS score: b = 1.08 [95% CI, 0.01-2.14]) and when restricted to natural conceptions (externalizing problems: b = 0.45 [95% CI, 0.07-0.83]; SRS score: b = 1.12 [95% CI, -0.09 to 2.34]). Offspring of parents with subfecundity had higher odds of ASD (overall: odds ratio [OR], 1.27 [95% CI, 1.03-1.57]; natural conceptions: OR, 1.31 [95% CI, 1.04-1.64]). Children conceived via non-IVF treatment had higher odds of ADHD compared with those conceived via natural conception with subfecundity (OR, 1.77 [95% CI, 1.16-2.68]) or without subfecundity (OR, 1.54 [95% CI, 1.05-2.25]). There were no significant associations for IVF treatment. Conclusions and Relevance: In this large US cohort study, subfecundity was associated with elevated scores for caregiver-reported symptoms of behavioral problems and higher odds of ASD diagnosis, independent of infertility treatment. Non-IVF treatment was associated with ADHD, warranting further research into specific indications for treatment that may increase risk of offspring neurodevelopmental problems.