- Subclinical hypothyroidism, high maternal thyrotropin, isolated hypothyroxinemia, and thyroid peroxidase (TPO) antibody positivity in pregnancy are associated with increased risk for preterm birth, according to a systematic review and meta-analysis.
Why this matters
- This study suggests that thyroid screening during pregnancy may be beneficial.
- 3.1% of women had subclinical hypothyroidism (increased thyrotropin concentration with normal free thyroxine), 2.2% had isolated hypothyroxinemia (decreased free thyroxine with normal thyrotropin concentration), and 7.5% were TPO antibody positive.
- 5.0% of women experienced preterm birth (gestational age
- 0.7% had very preterm birth (gestational age
- Subclinical hypothyroidism (6.1% vs euthyroid, 5.0%; OR, 1.29; 95% CI, 1.01-1.64).
- Isolated hypothyroxinemia (7.1% vs 5.0%; OR, 1.46; 95% CI, 1.12-1.90).
- High maternal thyrotropin concentration (OR, 1.04; 95% CI, 1.00-1.09 per standard deviation).
- TPO antibody positivity (6.6% vs 4.9% for negativity; OR, 1.33; 95% CI, 1.15-1.56).
- 19 cohorts including 47,045 pregnant women were subjected to meta-analysis.
- Funding: Netherlands Organization for Scientific Research.
- Only observational studies were included.