Prevalence of Subclinical Hypothyroidism among Pregnant Women

Abstract

Background: Some studies have associated subclinical hypothyroidism with obstetric complications such as preeclampsia, preterm birth, and placental abruption. Objective: To investigate the prevalence of subclinical hypothyroidism in patients with preeclampsia and normotensive pregnant women ending their pregnancy at Enrique Garces Hospital. Methods: This is a descriptive cross-sectional study conducted between February 2020 and 2022. The study included pregnant women between 20 and 35 years of age, with singleton pregnancies in the third trimester. The women were in labor and diagnosed with subclinical hypothyroidism and preeclampsia in the current pregnancy. The women underwent blood sampling. Also, the thyroid stimulating hormone (TSH) and free thyroxine (fT4) levels were measured by chemiluminescence. Results: A total of 639 women were evaluated; Among these women 509 (79.66%) were normotensive, 137 (26.92%) had subclinical hypothyroidism, and 372 (73.08%) did not have subclinical hypothyroidism, 130 (20.34%) had preeclampsia, 34 (26.15%) of them with subclinical hypothyroidism and 96 (73.85%) not having subclinical hypothyroidism. The overall prevalence of subclinical hypothyroidism was 26.76%. In the normotensive group the prevalence of subclinical hypothyroidism was 0.2691 with a 95 % CI (0.2306, 0.3076) and in the preeclampsia group it was 0.2615 with a 95 % CI (0.1859, 0.3370). Conclusions: A high prevalence of subclinical hypothyroidism was identified among pregnant women, which often goes undiagnosed in the early stages of pregnancy due to the lack of thyroid profile screening protocols for all pregnant women. Regarding the TSH cut-off levels 3mIUI/L there was no statistically significant difference of subclinical hypothyroidism among normotensive pregnant women and preeclampsia women, as literature suggests that TSH levels above 4mIU/L are associated with hypertensive diseases