Table 5. Associations between Birth Spacing and Non-ASD Developmental Disabilities Subtypes, Study to Explore Early Development (SEED), United States.

Inter-pregnancy Interval (m)	Total Sample Unadjusted OR (95% CI)	Total Sample, Adjustment for sociodemographics aOR† (95% CI)	Term Birth Sample, Adjustment for sociodemographics aOR† (95% CI)	Term Birth Sample, Adjustment for sociodemographics + maternal report of trying to get pregnant aOR† (95% CI)	Term Birth Sample, Adjustment for sociodemographics + maternal infertility disorder aOR† (95% CI)	Term Birth Sample, Adjustment for sociodemographics + prenatal hypertension, diabetes aOR† (95% CI)
DD with ID
<18	0.7 (0.4–1.1)	0.7 (0.4–1.2)	0.7 (0.4–1.3)	0.7 (0.4–1.3)	0.7 (0.4–1.3)	0.6 (0.3–1.2)
18–59	Ref	Ref	Ref	Ref	Ref	Ref
≥60	1.6 (0.98–2.5)	1.1 (0.7–1.9)	1.3 (0.7–2.4)	1.4 (0.8–2.8)	1.5 (0.8–2.8)	1.2 (0.6–2.3)
DD w/outID
<18	1.0 (0.7–1.3)	1.0 (0.8–1.4)	1.1 (0.8–1.4)	1.0 (0.8–1.5)	1.0 (0.8–1.4)	1.0 (0.7–1.3)
18–59	Ref	Ref	Ref	Ref	Ref	Ref
≥60	1.1 (0.8–1.6)	1.1 (0.7–1.5)	1.2 (0.8–1.8)	1.2 (0.8–1.9)	1.2 (0.8–1.9)	1.1 (0.7–1.7)
DD with autism symptoms
<18	1.0 (0.7–1.5)	1.0 (0.6–1.5)	1.0 (0.6–1.6)	0.9 (0.5–1.4)	0.9 (0.6–1.5)	0.6 (0.3–1.2)
18–59	Ref	Ref	Ref	Ref	Ref	Ref
≥60	1.5 (0.98–2.4)	1.2 (0.7–2.0)	1.3 (0.7–2.3)	1.4 (0.7–2.6)	1.4 (0.7–2.6)	0.9 (0.4–2.1)
DD w/out autism symptoms
<18	0.9 (0.7–1.2)	0.9 (0.7–1.3)	1.0 (0.7–1.4)	1.0 (0.7–1.4)	1.0 (0.7–1.4)	1.0 (0.70–1.3)
18–59	Ref	Ref	Ref	Ref	Ref	Ref
≥60	1.2 (0.8–1.7)	1.1 (0.8–1.6)	1.2 (0.8–1.8)	1.2 (0.8–1.9)	1.2 (0.8–1.9)	1.2 (0.8–1.8)

DD is other (non-ASD) developmental delay; ID is intellectual disability.

^†aOR is adjusted odds ratio, derived from logistic regression models in which the each DD case sub-group is compared to the POP (general population) control group. All models include adjustment for child sex, maternal age at birth, maternal education at birth, and maternal race/ethnicity. Supplemental models additionally adjusted for various potential mediator factors as indicated.