The impact of maternal hypothyroidism during pregnancy on neonatal outcomes: a systematic review and meta-analysis

The effects of maternal hypothyroidism on neonatal outcomes were not definitely confirmed. We conduct a systematic review of the literatures on the impact of maternal hypothyroidism on neonatal outcomes. We searched Pubmed, Embase and the Cochrane Controlled Trials Register databases complemented by manual searches in article references without language restrictions published from 1946 to April 2015. Nine trials are included. For preterm birth in pregnancies of hypothyroidism women, there is an increased tendency (RR 1.18; 95% CI 0.99 to 1.40; p = 0.06). The same result is seen relating to the low birth weight (RR 1.31; 95% CI 1.00 to 1.72; p = 0.05). Regarding small for gestational age there is no significant increase. Children who were born from mothers with hypothyroidism during pregnancy have increased birth weight (MD 32.35, 95% CI 7.46 to 57.24; p = 0.01). The impact of maternal hypothyroidism shows a trend of reduced risk of large for gestational age (RR 1.17; 95% CI 0.99 to 1.38; p = 0.06). Our review suggests that mothers with hypothyroidism during pregnancy are more likely to give birth to children with higher birth weight or LGA, and L-T4 supplementation should be recommended. The risk of preterm birth and low birth weight also tends to be higher in children with hypothyroidism mothers.