Maternal hypothyroidism linked to adverse pregnancy outcomes

Pregnant women with high levels of thyroid stimulating hormone (TSH), which indicate hypothyroidism, are at risk of adverse pregnancy outcomes, a study has found.

The retrospective cohort study included 14,744 singleton pregnancies from the North Denmark Region Pregnancy Cohort (2011−2015). Maternal TSH, thyroid peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (Tg-Ab) were measured in early pregnancy blood samples.

Researchers performed regression analyses to estimate the associations between maternal hypothyroidism (TSH cutoffs: 6.0 and 10 mIU/L), thyroid autoimmunity (TPO-Ab cutoff: 60 U/ml, Tg-Ab cutoff: 33 U/ml), and adverse pregnancy outcomes.

Of the women, 93.2 percent had live births, 6.5 percent had spontaneous abortions, and 0.3 percent had stillbirths. The frequency of spontaneous abortion was 6.5 percent when TSH was <6.0 mIU/L, 6.5 percent when TSH was >6.0 mIU/L (adjusted odds ratio [aOR], 1.0, 95 percent confidence interval [CI], 0.5−2.0), and 12.5 percent when TSH was >10 mIU/L (aOR, 2.0, 95 percent CI, 0.8−5.2).

The frequency of preterm birth was 5.4 percent when TSH was <6.0 mIU/L, 7.8 percent when >6.0 mIU/L (aOR, 1.5, 95 percent CI, 0.7−2.9), and 11.4 percent when >10 mIU/L (aOR, 2.6, 95 percent CI, 0.9–7.3).

Thyroid autoantibodies showed no association with either spontaneous abortion (TPO-Ab: aOR, 1.0, 95 percent CI, 0.8−1.3; Tg-Ab: aOR, 1.0, 95 percent CI, 0.8−1.2) or preterm birth (TPO-Ab: aOR, 1.0, 95 percent CI, 0.8–1.2; Tg-Ab: aOR, 0.9, 95 percent CI, 0.7–1.2).