Table 6.
Odds Ratios for Autism Spectrum Disorder According to Maternal Metabolic Conditions Present During Pregnancya and Category of Maternal Iron Intake During the Index Period,b CHARGE Study, California, 2003–2009
| Category of Mean Iron Intake, mg/day | No Maternal Metabolic Condition |
Maternal Metabolic Condition |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No. With TD | No. With ASD | ORc | 95% CI | P Value | No. With TD | No. With ASD | ORc | 95% CI | P Value | |
| Highest quintile (≥86) | 53 | 54 | 1 | Reference | 7 | 9 | 1.51 | 0.39, 5.84 | 0.55 | |
| Middle 3 quintiles (30–<86) | 148 | 195 | 1.60 | 0.98, 2.61 | 0.06 | 23 | 41 | 2.21 | 1.01, 4.31 | 0.048 |
| Lowest quintile (<30) | 48 | 71 | 1.56 | 0.87, 2.78 | 0.13 | 6 | 27 | 4.72d | 1.69, 13.15 | 0.003 |
Abbreviations: ASD, autism spectrum disorder; CHARGE, Childhood Autism Risks from Genetics and the Environment; CI, confidence interval; OR, odds ratio; TD, typical development.
a Metabolic conditions included obesity (prepregnancy body mass index (weight (kg)/height (m)2) ≥30), hypertension, and/or diabetes.
b The index period was defined as the period from 3 months before pregnancy through breastfeeding.
c Adjusted for maternal education, race/ethnicity, and periconceptional folic acid intake; child's birth year and sex; home ownership; type of health insurance; and regional center catchment area.
d The P value for multiplicative interaction was 0.01 for the lowest quintile of iron intake. The expected odds ratios for the combination of the lowest quintile of iron intake and maternal metabolic conditions were 2.07 and 2.36 in the additive and multiplicative models, respectively.