Maternal thyroid deficiency and pregnancy complications: implications for population screening

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Perinatal Medicine

Background:

• Thyroid hormones play a crucial role in maternal and fetal well-being during pregnancy.
• Subclinical hypothyroidism, indicated by elevated TSH, may impact pregnancy outcomes.
• Routine prenatal care often includes TSH screening, but its association with specific complications requires further investigation.

Purpose of the Study:

• To investigate the relationship between second-trimester thyroid stimulating hormone (TSH) levels and various pregnancy complications.
• To identify specific adverse obstetrical outcomes associated with elevated TSH in pregnant women.

Main Methods:

• A cohort of 9403 pregnant women had their serum TSH levels measured during the second trimester.
• Data on pregnancy complications including vaginal bleeding, premature delivery, low birthweight, abruptio placentae, pregnancy-induced hypertension, cesarean section, low Apgar scores, and fetal/neonatal death were collected.
• Statistical analysis was performed to determine the association between TSH levels and adverse outcomes.

Main Results:

• Elevated TSH (≥ 6 mU/l) was observed in 2.2% of the cohort.
• Women with elevated TSH had a significantly higher rate of fetal death (3.8%) compared to those with normal TSH (0.9%).
• No significant association was found between elevated TSH and other assessed pregnancy complications.

Conclusions:

• Increased fetal death is the primary adverse obstetrical outcome associated with elevated TSH from the second trimester onwards in the general pregnant population.
• Thyroid hormone replacement therapy could potentially mitigate this risk, supporting the consideration of population-wide TSH screening during pregnancy.