High TSH levels and thyroid autoimmunity in early pregnancy may detrimentally affect pregnancy and birth outcomes.

The authors determined the association between metabolic syndrome in early pregnancy (mean, 11.96 weeks) and the risk of preterm birth in the mother-child cohort study ("Rhea" Study) in Crete, Greece, 2007-2009. Maternal fasting serum samples were collected, and blood pressure was measured at the time of the first major ultrasound examination (n = 625). Multivariable log-binomial regression models were used. Women with metabolic syndrome were at high risk for preterm birth (relative risk (RR) = 2.93, 95% confidence interval (CI): 1.53, 5.58), with the highest risk observed for medically indicated preterm births (RR = 5.13, 95% CI: 1.97, 13.38). Among the components of metabolic syndrome, the most significant risk factor was hypertension (RR = 2.32, 95% CI: 1.28, 4.20). An elevation of 10 mm Hg in diastolic blood pressure increased the relative risk for preterm birth by 29% (RR = 1.29, 95% CI: 1.08, 1.53), while a per unit increase in the low density lipoprotein/high density lipoprotein cholesterol ratio increased this risk by 19% (RR = 1.19, 95% CI: 1.02, 1.39). Fetal weight growth restriction was associated with elevated levels of insulin (RR = 1.14, 95% CI: 1.08, 1.20) and diastolic blood pressure (RR = 1.27, 95% CI: 1.00, 1.61) in early pregnancy. These findings suggest that women with metabolic syndrome in early pregnancy had higher risk for preterm birth.

The role of intrauterine environment in the development of obesity is increasingly recognised. Adipokines and specifically leptin have been examined as potential biomarkers predicting early development of obesity. We conducted a systematic review and meta-analysis of the epidemiological evidence for the association between leptin levels in cord blood and anthropometric measurements at birth in healthy mother-newborn pairs. A PubMed search was performed between 1994 and 2009 and manual search of reference lists of retrieved articles. Forty-four studies met the inclusion criteria set. All studies reported a positive correlation between leptin levels and birthweight. The combined correlation coefficient (r) was 0.46 [95%CI 0.43, 0.50]. Leptin levels explained 21% of variation in birthweight. Results were similar in males (r=0.55; 0.40, 0.68) and females (r=0.60; 0.50, 0.69), and between Caucasians (r=0.45; 0.39, 0.51) and eastern Asian populations (r=0.47; 0.37, 0.55). Statistically significant positive correlations were also found for birth length (r=0.29; 0.23, 0.34) and ponderal index (r=0.36; 0.31, 0.41). There was no indication of publication bias (Egger's test P-value=0.23). This meta-analysis shows a clear but moderate correlation between leptin levels in cord blood and birthweight that is observed in different population groups.

Key PointsQuestionIs exposure to ambient air pollution in the first trimester associated with thyroid function throughout pregnancy?FindingsAmong 9931 pregnant women in 4 European cohorts and 1 US cohort, an increase of 5 μg/m3 in exposure to particulate matter with an aerodynamic diameter of 2.5 μm or less was associated with 20% higher odds of hypothyroxinemia.MeaningThe findings of this study raise the possibility that exposure to particulate matter might disrupt thyroid function in pregnant women.