# Evaluation of the therapeutic efficacy of different doses of LT4 in pregnant women with high-normal TSH levels and TPOAb positivity in the first half of pregnancy

## TL;DR

This study found that 50 µg of levothyroxine improved outcomes in pregnant women with high-normal TSH and TPOAb positivity, reducing risks like SIBO and spontaneous abortion.

## Contribution

The study demonstrates that 50 µg levothyroxine is more effective than lower doses or no treatment in improving maternal and neonatal outcomes in this specific pregnancy group.

## Key findings

- 50 µg levothyroxine reduced TSH, triglycerides, and LDL levels compared to the nonintervention group.
- The 50 µg group had lower rates of abdominal distension, SIBO, and premature membrane rupture.
- Newborns in the 50 µg group had higher weight and longer length compared to other groups.

## Abstract

The objective was to investigate the efficacy of different doses of levothyroxine therapy among pregnant women exhibiting high-normal thyroid stimulating hormone levels and positive thyroid peroxidase antibodies throughout the first half of pregnancy.

Pregnant women exhibiting high-normal thyroid stimulating hormone levels and thyroid peroxidase antibodies positivity throughout the initial half of pregnancy were selected from January 2021 to September 2023. Based on the different doses of levothyroxine, the pregnant women were categorized into the nonintervention group (G0, 122 women), 25 µg levothyroxine intervention group (G25, 69 women), and 50 µg levothyroxine intervention group (G50, 58 women). Serum parameters, gastrointestinal symptoms, small intestinal bacterial overgrowth (SIBO), maternal and neonatal outcomes were compared after the intervention among the three groups.

After the intervention, in the G25 and G50 groups, the thyroid stimulating hormone, triglyceride and low-density lipoprotein levels were notably less in contrast to those in the G0 group (P < 0.05). The rates of abdominal distension and SIBO in the G25 and G50 groups were notably lower in contrast to the G0 group (P = 0.043 and 0.040, respectively). The G50 group had a lower rate of spontaneous abortion and premature membrane rupture than the G0 group (P = 0.01 and 0.015, respectively). Before 11+ 2 weeks of gestation and at thyroid peroxidase antibodies levels ≥ 117 IU/mL, in contrast to the G0 group, the G50 group experienced a decreased rate of spontaneous abortion (P = 0.008). The G50 group had significantly higher newborn weight than the G0 group (P = 0.014), as well as a notably longer newborn length than the G0 and G25 groups (P = 0.005).

For pregnant women with high-normal thyroid stimulating hormone levels and thyroid peroxidase antibodies positive during the first half of pregnancy, supplementation with 50 µg levothyroxine was more effective in improving their blood lipid status and gastrointestinal symptoms, reducing the incidence of SIBO and premature rupture of membranes, and before 11+2 weeks, TPOAb ≥ 117 IU/mL proved more beneficial in mitigating the risk of spontaneous abortion.

The online version contains supplementary material available at 10.1186/s12944-024-02099-9.