Maternal thyroid deficiency and pregnancy complications: implications for population screening

Objective-To examine the relation between certain pregnancy complications a nd thyroid stimulating hormone (TSH) measurements in a cohort of pregnant w omen. Methods-TSH was measured in sera obtained from women during the second trim ester as part of routine prenatal care. Information was then collected abou t vaginal bleeding, premature delivery, low birthweight, abruptio placentae , pregnancy induced hypertension, need for cesarean section, low Apgar scor es, and fetal and neonatal death. Results-Among 9403 women with singleton pregnancies, TSH measurements were 6 mU/l or greater in 209 (2.2%). The rate of fetal death was significantly higher in those pregnancies (3.8%) than in the women with TSH less than 6 m U/l (0.9%, odds ratio 4.4, 95% confidence interval 1.9-9.5). Other pregnanc y complications did not occur more frequently Conclusion-From the second trimester onward, the major adverse obstetrical outcome associated with raised TSH in the general population is an increase d rate of fetal death. If thyroid replacement treatment avoided this proble m this would be another reason to consider population screening.