# Associations Between Overt and Subclinical Hypothyroidism in Pregnancy and Adverse Maternal and Neonatal Outcomes: A cohort study

## TL;DR

This study found that hypothyroidism during pregnancy is linked to a higher risk of iron deficiency anemia at delivery but not to other major maternal or neonatal complications, likely due to effective treatment.

## Contribution

The study provides new evidence on the specific association between hypothyroidism in pregnancy and iron deficiency anemia, while showing no significant links to other adverse outcomes.

## Key findings

- Hypothyroidism during pregnancy was significantly associated with iron deficiency anemia at delivery.
- No significant associations were found with gestational diabetes, hypertension, or pre-eclampsia.
- Effective thyroxine therapy may explain the lack of increased risk for most adverse outcomes.

## Abstract

This study aimed to determine associations between hypothyroidism during pregnancy and selected maternal and neonatal outcomes.

A retrospective, cohort study was conducted between January 2018 and December 2020 at the two main tertiary hospitals in Muscat, Oman. The study included 408 Omani pregnant women aged 18–45 years. Participants were divided into two groups: those diagnosed with overt or subclinical hypothyroidism (n = 201; exposed group) and those with normal thyroid function (n = 207; unexposed group), matched for relevant variables. Data were collected from electronic medical records to assess maternal and neonatal outcomes.

Most exposed women (94.5%) had overt hypothyroidism. No significant differences were observed between the two groups in gestational diabetes mellitus, gestational hypertension, or pre-eclampsia (P >0.05). Women with hypothyroidism had a significantly higher risk of iron deficiency anaemia at delivery (relative risk: 2.22, 95% confidence interval: 1.68–2.94; P = 0.05).

Hypothyroidism during pregnancy was not associated with an increased risk of most adverse maternal or neonatal outcomes in this cohort. This may be attributed to the effective management of hypothyroidism, as the majority of affected women were on thyroxine therapy, maintaining a clinically and biochemically euthyroid state throughout pregnancy.