No abstract

IMPORTANCE Maternal hypothyroidism and hyperthyroidism are risk factors for preterm birth. Milder thyroid function test abnormalities and thyroid autoimmunity are more prevalent, but it remains controversial if these are associated with preterm birth. OBJECTIVE To study if maternal thyroid function test abnormalities and thyroid autoimmunity are risk factors for preterm birth. DATA SOURCES AND STUDY SELECTION Studies were identified through a search of the Ovid MEDLINE, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, and Google Scholar databases from inception to March 18, 2018, and by publishing open invitations in relevant journals. Data sets from published and unpublished prospective cohort studies with data on thyroid function tests (thyrotropin [often referred to as thyroid-stimulating hormone or TSH] and free thyroxine [FT 4 ] concentrations) or thyroid peroxidase (TPO) antibody measurements and gestational age at birth were screened for eligibility by 2 independent reviewers. Studies in which participants received treatment based on abnormal thyroid function tests were excluded. DATA EXTRACTION AND SYNTHESIS The primary authors provided individual participant data that were analyzed using mixed-effects models. MAIN OUTCOMES AND MEASURES The primary outcome was preterm birth (<37 weeks' gestational age). RESULTS From 2526 published reports, 35 cohorts were invited to participate. After the addition of 5 unpublished data sets, a total of 19 cohorts were included. The study population included 47 045 pregnant women (mean age, 29 years; median gestational age at blood sampling, 12.9 weeks), of whom 1234 (3.1%) had subclinical hypothyroidism (increased thyrotropin concentration with normal FT 4 concentration), 904 (2.2%) had isolated hypothyroxinemia (decreased FT 4 concentration with normal thyrotropin concentration), and 3043 (7.5%) were TPO antibody positive; 2357 (5.0%) had a preterm birth. The risk of preterm birth was higher for women with subclinical hypothyroidism than euthyroid women (6.1% vs 5.0%, respectively; absolute risk difference, 1.4% [95% CI, 0%-3.2%]; odds ratio [OR], 1.29 [95% CI, 1.01-1.64]). Among women with isolated hypothyroxinemia, the risk of preterm birth was 7.1% vs 5.0% in euthyroid women (absolute risk difference, 2.3% [95% CI, 0.6%-4.5%]; OR, 1.46 [95% CI, 1.12-1.90]). In continuous analyses, each 1-SD higher maternal thyrotropin concentration was associated with a higher risk of preterm birth (absolute risk difference, 0.2% [95% CI, 0%-0.4%] per 1 SD; OR, 1.04 [95% CI, 1.00-1.09] per 1 SD). Thyroid peroxidase antibody-positive women had a higher risk of preterm birth vs TPO antibody-negative women (6.6% vs 4.9%, respectively; absolute risk difference, 1.6% [95% CI, 0.7%-2.8%]; OR, 1.33 [95% CI, 1.15-1.56]). CONCLUSIONS AND RELEVANCE Among pregnant women without overt thyroid disease, subclinical hypothyroidism, isolated hypothyroxinemia, and TPO antibody positivity were significantly associated with higher risk of preterm birth. These results provide i...

Higher circulating concentration of maternal 25(OH)D(3) in pregnancy was associated with improved mental and psychomotor development in infants.

This study in two birth cohorts with moderately high obesity prevalence suggests that maternal pre-pregnancy obesity is associated with reduced child cognitive development at early ages. This association appears more likely to be due to maternal than shared family and social mechanisms, but further research is needed to disentangle a direct intrauterine effect from other maternal confounding factors.

Studies on hypothyroidism and hyperthyroidism implicate that adequate maternal thyroid hormone availability is required for optimal fetal growth and development. Studies on the association of mild thyroid function test abnormalities with birth weight report heterogeneous results. Some studies indicate that high FT4 concentrations are associated with lower birth weight which could have implications for the treatment target in women already on levothyroxine therapy. We searched Medline (Ovid), Embase.com, Web-of-Science, Cochrane CENTRAL and Google Scholar up to March 18 th , 2018 and collected data on serum thyroid function tests and antibody status during pregnancy and birth weight from prospective cohort studies including treatment-naïve pregnant women.

Pregnancy adherence to the MD was not associated with childhood overweight risk, but it was associated with lower WC, a marker of abdominal obesity.

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.

We found an association between low maternal urinary iodine and lower cognitive scores in childhood, although only when corrected for creatinine, adding to the evidence that iodine deficiency may have potential harmful effects on neurodevelopment. Iodine supplementation does not appear to improve child's neurodevelopment at 4-5 years.