Neonatal Effects of Maternal Hypothyroidism

The thyroid gland controls the metabolic rate and regulates growth and development. Hypothyroidism is the underproduction of thyroid hormones. If left untreated, maternal hypothyroidism can have profound effects on a newborn.

Pregnancy Risk

• Severe maternal hypothyroidism can cause preeclampsia (toxemia), placental abnormalities and abruptio placentae, all of which pose significant risks for the fetus. According to Olds' Maternal-Newborn Nursing, there is a 50 percent increased risk of spontaneous miscarriage.

Lower IQ

• One-third of the infants of untreated mothers showed significantly lower IQ scores. This is nearly twice the rate of babies born to mothers with normal thyroid levels.

Motor and Gait

• Maternal hypothyroidism during pregnancy has been shown to increase the risk of delayed psychomotor development in infants.

Combined Maternal and Fetal Hypothyroidism

• The effects of combined maternal and fetal hypothyroidism are more severe than maternal hypothyroidism alone. Such cases can lead to severe cretinism, a congenital condition of stunted physical development and extremely low IQ (around 29) caused by severe thyroid deficiency.

Treatment

• Treatment during pregnancy consists of replacement of thyroid hormone with synthetic levothyroxine. If possible, a woman should be treated for hypothyroidism before becoming pregnant. Adequate treatment during pregnancy can prevent the negative effects of maternal hypothyroidism.