Preterm birth complicates 5% to 15% of births worldwide. It is the most important direct cause of morbidity and mortality in children younger than 5 years,¹ and is an important risk factor for psychiatric, metabolic, cardiovascular, and renal disease later in life.^2,3 However, in the majority of cases, no known risk factors can be identified.^4,5

OBJECTIVE: To investigate whether circulating 25-hydroxyvitamin D₃ [25(OH)D₃] concentration in pregnancy is associated with neuropsychological development in infants. METHODS: The Spanish population-based cohort study INfancia y Medio Ambiente Project recruited pregnant women during the first trimester of pregnancy between November 2003 and February 2008. Completed data on 1820 mother-infant pairs were used. Maternal plasma 25(OH)D₃ concentration was measured by high-performance liquid chromatography in pregnancy (mean 13.5±2.1 weeks of gestation). Offspring mental and psychomotor scores were assessed by trained psychologists at age 14 months (range, 11–23) by using the Bayley Scales of Infant Development. β-Coefficients with 95% confidence intervals (CIs) of mental and psychomotor scores associated with continuous or categorical concentrations of maternal plasma 25(OH)D₃ were calculated by using linear regression analysis. RESULTS: The median plasma value of 25(OH)D₃ in pregnancy was 29.6 ng/mL (interquartile range, 21.8–37.3). A positive linear relationship was found between circulating concentrations of maternal 25(OH)D₃ concentrations in pregnancy and mental and psychomotor scores in the offspring. After adjustment for potential confounders, infants of mothers with 25(OH)D₃ concentrations in pregnancy >30 ng/mL showed higher mental score (β = 2.60; 95% CI 0.63–4.56) and higher psychomotor score (β = 2.32; 95% CI 0.36–4.28) in comparison with those of mothers with 25(OH)D₃ concentrations <20 ng/mL. CONCLUSIONS: Higher circulating concentration of maternal 25(OH)D₃ in pregnancy was associated with improved mental and psychomotor development in infants.

Background: The fetus depends on maternal thyroid hormones during pregnancy for normal brain development. Little is known about the effects of subclinical hypothyroidism and mild hypothyroxinemia during pregnancy on neurodevelopment of the child. Methods: We evaluated a population-based birth cohort in Spain. A total of 1761 children and their mothers were included in the main analyses. Serum levels of free thyroxine and thyrotropin were measured in pregnant women. Mental and psychomotor development of their children was assessed using the Bayley Scales of Infant Development during the second year of life. Results: Low free thyroxine levels (<5th percentile) and self-reported prepregnancy thyroid disorder without medical treatment were associated with a decrease of mental scores (Beta = −3.4 [95% confidence interval= −6.7 to −0.2]) and −5.5 [−8.9 to −2.0], respectively). No association between thyrotropin levels and mental scores or psychomotor scores was observed. Conclusions: Low free thyroxine levels in healthy pregnant women are related to a moderate delay in child neurodevelopment. The impairment is similar in magnitude to that observed in mothers with untreated prepregnancy thyroid disorder. The value of screening pregnant women for thyroid function requires further assessment, particularly in mildly iodine-deficient areas.

Background: Acetaminophen is extensively used during pregnancy. But there is a lack of population-representative cohort studies evaluating its effects on a range of neuropsychological and behavioural endpoints. We aimed to assess whether prenatal exposure to acetaminophen is adversely associated with neurodevelopmental outcomes at 1 and 5 years of age.

Seafood consumption during pregnancy is thought to be beneficial for child neuropsychological development, but to our knowledge no large cohort studies with high fatty fish consumption have analyzed the association by seafood subtype. We evaluated 1,892 and 1,589 mother-child pairs at the ages of 14 months and 5 years, respectively, in a population-based Spanish birth cohort established during 2004–2008. Bayley and McCarthy scales and the Childhood Asperger Syndrome Test were used to assess neuropsychological development. Results from multivariate linear regression models were adjusted for sociodemographic characteristics and further adjusted for umbilical cord blood mercury or long-chain polyunsaturated fatty acid concentrations. Overall, consumption of seafood above the recommended limit of 340 g/week was associated with 10-g/week increments in neuropsychological scores. By subtype, in addition to lean fish, consumption of large fatty fish showed a positive association; offspring of persons within the highest quantile (>238 g/week) had an adjusted increase of 2.29 points in McCarthy general cognitive score (95% confidence interval: 0.42, 4.16). Similar findings were observed for the Childhood Asperger Syndrome Test. Beta coefficients diminished 15%–30% after adjustment for mercury or long-chain polyunsaturated fatty acid concentrations. Consumption of large fatty fish during pregnancy presents moderate child neuropsychological benefits, including improvements in cognitive functioning and some protection from autism-spectrum traits.