March 22 (UPI) -- Research during the last 30 years has led to recommendations for universal screening of and treatment for subclinical hypothyroidism in pregnant women, but a new study suggests they do not improve health outcomes for mothers or their babies.
Research from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units, or MFMU, Network found that treatment for subclinical hypothyroidism or hypothroxinemia during pregnancy did not result in significantly better cognitive outcomes in children through age 5 compared to no treatment.
"The results of our study, the largest and most rigorous on this issue, do not support screening for subclinical hypothyroidism or hypothroxinemia during pregnancy," Dr. Dwight Rouse, principal investigator for the MFMU at Brown University/Women & Infants Hospital of Rhode Island, said in a press release. "Our results do not apply to women with actual hypothyroidism during pregnancy -- such women should be treated during pregnancy, as treatment benefits them and their babies."
Researchers screened women with singleton pregnancies before 20 weeks of gestation for subclinical hypothyroidism. Participants were randomly given levothyroxine, a drug to treat hypothyroidism, or a placebo.
The participants were assessed for thyroid function monthly throughout pregnancy and their children were tested for developmental and behavioral levels for five years. Research showed that treatment for subclinical hypothyroidism did not improve cognitive outcomes in the children and did not improve obstetric or neonatal outcomes.
The study was published in the New England Journal of Medicine.