Context Prenatal folic acid supplements reduce the risk of neural tube defects in children, but it has not been determined whether they protect against other neurodevelopmental disorders. Objective To examine the association between maternal use of prenatal folic acid supplements and the subsequent risk of autistic disorder in children. Design, Setting, and Patients The study sample of 85,176 was derived from the population-based, prospective Norwegian Mother and Child Cohort Study (MoBa). The children were born in 2002–08. By the end of follow-up on March 31st, 2012, the age range was 3.3–10.2 years and the mean age 6.4 years. The exposure of primary interest was use of folic acid from 4 weeks before to 8 weeks after the start of pregnancy. The start of pregnancy was defined as the first day of the last menstrual period before conception. Relative risks of ASD were estimated by odds ratios (ORs) with 95% confidence intervals (CIs) in a logistic regression analysis. Analyses were adjusted for maternal education level, year of birth, and parity. Main Outcome Measure Specialist-confirmed diagnosis of autistic disorder. Results To date, 114 children in the study sample have been diagnosed with autistic disorder. In children whose mothers took folic acid, 0.10% (64/61,042) had autistic disorder, compared with 0.21% (50/24,134) in those unexposed to folic acid. The adjusted OR for autistic disorder in children of folic acid users was 0.61 (95% CI, 0.41–0.90). Similar analyses for prenatal fish oil supplements showed no such association with autistic disorder, even though fish oil use was associated with the same maternal characteristics as folic acid use. Conclusion Prenatal folic acid supplements around the time of conception were associated with a lower risk of autistic disorder in the MoBa cohort.

BACKGROUND: Numerous studies have investigated the prevalence of neurologic and neurodevelopmental disorders individually, but few have examined them collectively, and there is uncertainty as to what extent they overlap. METHODS: The study has determined the proportions of children aged 0 to 11 years with diagnoses of autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), epilepsy, and cerebral palsy (CP) in Norway. The data were obtained from the Norwegian Patient Register, which is nationwide and contains diagnoses assigned by Norwegian specialist health services (hospitals and outpatient clinics). The Norwegian Patient Register started collecting individual-level data in 2008, and the follow-up period for the study is years 2008 through 2010. RESULTS: For ASD, ADHD, and epilepsy, the proportions were highest in the oldest children. At age 11 years, the incidence was 0.7% for ASD, 2.9% for ADHD, and 0.9% for epilepsy. The cumulative incidence is likely to be higher because some cases diagnosed before 2008 were probably missed. For CP, the proportions were ∼0.3% for age ≥5 years. There was considerable overlap between diagnoses. For all disorders, boys had a significantly increased risk. In school-age children (aged 6–11 years) the male/female ratio was 4.3 for ASD, 2.9 for ADHD, 1.2 for epilepsy, and 1.3 for CP. CONCLUSIONS: The findings demonstrate the significant burden of disease associated with neurologic and neurodevelopmental disorders in children and that this burden is disproportionately skewed toward boys.

Summary Purpose Antiepileptic drugs may cause congenital malformations. Less is known about the effect on development in infancy and childhood. The aim of this study was to examine whether exposure to antiepileptic drugs during pregnancy has an impact on early child development. Methods From mid-year 1999 through December 2008, children of mothers recruited at 13–17 weeks of pregnancy were studied in the ongoing prospective Norwegian Mother and Child Cohort Study. Information on birth outcomes were obtained from the Medical Birth Registry (108,264 –children), and mothers reported on their child’s motor development, language, social skills, and autistic traits using items from standardized screening tools at 18 months (61,351 children) and 36 months of age (44,147 children). The relative risk of adverse outcomes in children according to maternal or paternal epilepsy with and without prenatal exposure to antiepileptic drugs was estimated as odds ratios (ORs), using logistic regression with adjustment for maternal age, parity, education, smoking, depression/anxiety, folate-supplementation, and child congenital malformation or low birth weight. Key findings A total of 333 children were exposed to antiepileptic drugs in utero. At 18 months, the exposed children had increased risk of abnormal scores for gross motor skills (7.1 % vs. 2.9 %; OR, 2.0; 95 % Confidence Interval [CI], 1.1–3.7) and autistic traits (3.5 % vs. 0.9 %; OR, 2.7; CI, 1.1–6.7) compared to children of parents without epilepsy. At 36 months, the exposed children had increased risk of abnormal score for gross motor skills (7.5 % vs. 3.3 %; OR, 2.2; CI, 1.1–4.2), sentence skills (11.2 % vs. 4.8 %; OR, 2.1; CI, 1.2–3.6), and autistic traits (6.0 % vs. 1.5 %; OR, 3.4; CI, 1.6–7.0). The drug-exposed children also had increased risk of congenital malformations (6.1 % vs. 2.9 %; OR, 2.1; CI, 1.4–3.4), but exclusion of congenital malformations did not affect the risk of adverse development. Children born to women with epilepsy who did not use antiepileptic drugs had no increased risks. Children of fathers with epilepsy generally scored within the normal range. Significance Exposure to antiepileptic drugs during pregnancy is associated with adverse development at 18 and 36 months of age, measured as low scores within key developmental domains rated by mothers. Exposures to valproate, lamotrigine, carbamazepine, or multiple antiepileptic drugs were associated with adverse outcome within different developmental domains.

Some studies suggest that prenatal infection increases risk of autism spectrum disorders (ASDs). This study was undertaken in a prospective cohort in Norway to examine whether we could find evidence to support an association of the prenatal occurrence of fever, a common manifestation of infection, with ASD risk. Prospective questionnaires provided maternal exposure data; case status was established from clinical assessments and registry linkages. In a large, prospectively ascertained cohort of pregnant mothers and their offspring, we examined infants born ⩾32 weeks for associations between fever exposure in each trimester and ASD risk using logistic regression. Maternal exposure to second-trimester fever was associated with increased ASD risk, adjusting for presence of fever in other trimesters and confounders (adjusted odds ratio (aOR), 1.40; 95% confidence interval, 1.09–1.79), with a similar, but nonsignificant, point estimate in the first trimester. Risk increased markedly with exposure to three or more fever episodes after 12 weeks' gestation (aOR, 3.12; 1.28–7.63). ASD risk appears to increase with maternal fever, particularly in the second trimester. Risk magnified dose dependently with exposure to multiple fevers after 12 weeks' gestation. Our findings support a role for gestational maternal infection and innate immune responses to infection in the pathogenesis of at least some cases of ASD.