Subclinical hypothyroidism (SCH) in pregnancy is associated with adverse foetomaternal outcomes. The literature is scarce with respect to maternal and perinatal outcomes in women with mild SCH (TSH levels between 2.5-4 mIU/L).
The primary objective of the study was to compare the pregnancy outcome between SCH and euthyroid women. The secondary objectives were to find out the proportion of women with SCH having thyroid peroxidase antibodies (TPOAb) and to see the effect of TPOAb positivity on foetomaternal outcomes.
A total of 178 pregnant women were recruited in the first trimester, and those with TSH between 0.1 and 2.4 mIU/L were considered as euthyroid and 2.5-4mIU/L were labelled as SCH. Women with SCH underwent testing for TPOAb. All women were followed until delivery, and foetomaternal outcomes were assessed.
Amongst SCH group, there was a significantly higher proportion of overweight and obese women (76/91 (83.51%) vs 59/87 (68%), p = 0.031). The neonatal intensive care unit (NICU) admission was higher with adjusted odds ratio of 3.24 (1.41-7.43) in women with SCH as compared to euthyroid women. Otherwise, there was no difference in foetomaternal outcomes between the two groups. The proportion of gestational diabetes mellitus, intrauterine growth retardation and still birth were higher in SCH women with TPOAb as compared to euthyroid. Amongst SCH women, the proportion of induced labour was lower (aOR:0.27 (0.08-0.93) whereas the proportion of stillbirth and low APGAR scores were higher in TPOAb-positive women with a statistically significant difference and adjusted odds ratio (aOR:20.18 (1.84-220.83)) and (aOR:4.77 (1.06-21.3)), respectively, when compared to TPOAb-negative women.
There appears to be no difference in pregnancy outcomes between women with SCH and euthyroid women except higher NICU admission in SCH group. Future multi-centre large prospective studies are required to understand better about the pregnancy outcomes in these women.

© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.