Effect of different initiation timing of levothyroxine on pregnancy outcomes and development of offspring in women with gestational subclinical hypothyroidism

Objective: To explore the impact of levothyroxine (L-T4) administration at different time points on pregnancy outcomes and offspring development in patients with subclinical hypothyroidism (SCH).

Methods: In this retrospective study, medical records of 107 patients with SCH treated in Huzhou Nanxun District People's Hospital from February 2021 to March 2023 were retrospectively reviewed. Of them, 55 patients received treatment before eight gestational weeks (Early group), and 52 patients received treatment after eight gestational weeks (Mid group). Levels of thyroid function indicators, occurrence of adverse pregnancy outcomes, occurrence of adverse reactions, and development of offspring before and after the treatment were compared.

Results: After the treatment, the thyroid function indicators in both groups improved compared to before treatment, and the improvement in the Early group was significantly better than that in the Mid group (P<0.05). The incidence of adverse pregnancy outcomes in the early group (5.45%) was lower than that in the mid group (19.23%) (P<0.05). There was no significant difference in the incidence of adverse reactions between the groups (P>0.05). The scores of fine motor, gross motor, language, personal-social behavior, and adaptability in offspring of patients the Early group were higher than those of the mid group (P<0.05).

Conclusions: Early administration of L-T4 is safe and can effectively improve thyroid function in SCH patients, reduce adverse pregnancy outcomes, and ensure growth and development of offspring.