Subclinical thyroid abnormalities may raise risk of preterm birth

Maternal subclinical thyroid abnormalities may be associated with an increased risk of preterm birth, an international study suggests.
Dutch-led researchers analysed data from 19 prospective cohort studies including more than 47,000 pregnant women in a study reported in JAMA.
The rate of preterm birth (at less than 37 weeks’ gestation) was 29% higher among women with subclinical hypothyroidism than among euthyroid women (6.1% vs 5.0%).
Compared with euthyroid women, those with isolated hypothyroxinaemia had 46% higher rates of preterm birth (7.1% vs 5.0%) and rates of very preterm birth (at less than 32 weeks) of 1.9% versus 0.8%.