First-trimester placental function in levothyroxine-using pregnant women: a case-control study

Abstract

We aimed to compare the pregnancy-associated plasma protein-A (PAPP-A) and the uterine artery pulsatility index (UtA PI) levels of euthyroid pregnant women using levothyroxine vs. a control group of uncomplicated pregnancies and to evaluate the effects of different levothyroxine dosages on pregnancy outcomes. We retrospectively evaluated 206 levothyroxine-using pregnant women by looking at their basic placental function markers and obstetric outcomes. A sample of 449 women whose pregnancies concluded with uncomplicated term deliveries composed of our control group. To examine the relationship between the levothyroxine dosages and the frequency of pregnancy complications, levothyroxine users were divided into different groups according to the 75, 100, and 150 mcg cutoffs. The median PAPP-A MoM levels of levothyroxine users were significantly lower at 0.94 vs. 1.11 (p < .001) and the median mean UtA PI was significantly higher than the control group at 2.08 vs. 1.74 (p < .0001). The median birth weight was significantly lower for the levothyroxine users’ group at 3292 g vs. 3427 g (p < .0001). Using 75, 100, and 150 mcg dose cutoffs, PAPP-A MoM, mean UtA PI and obstetric complication frequencies were not significantly different among levothyroxine users. Significant changes in placental function markers have been observed in euthyroid levothyroxine-using pregnant women during the first trimester. However, the frequency of obstetric complications does not appear to be dose dependent.

摘要

本研究旨在比较左旋甲状腺素治疗后甲状腺功能正常的孕妇与甲状腺功能正常孕妇孕早期妊娠相关血浆蛋白A（PAPP-A）和子宫动脉搏动指数（UtA-PI）水平, 并评价不同左旋甲状腺素剂量对妊娠结局的影响。我们回顾性分析了206例使用左旋甲状腺素治疗孕妇的孕早期胎盘功能指标和产科结局。对照组选择了无合并症足月分娩的449孕妇。为探讨左旋甲状腺素的剂量与妊娠并发症之间的关系, 将左旋甲状腺素使用者按照75mcg、100 mcg和150 mcg分为不同的组。左旋甲状腺素使用组PAPP-A-MoM值较对照组显著降低（0.9 vs. 1.11）（p<0.001）, UtA-PI的中位数显著高于对照组（2.08 vs. 1.74）（p<0.0001）。左甲状腺素使用组的出生体重的中位数显著低于对照组（3292克vs. 3427克）（p<0.0001）。左旋甲状腺素75mcg、100mcg和150 mcg不同剂量组之间的PAPP-A MoM值、UtA-PI和产科并发症发生率无显著差异。妊娠早期甲状旁腺素治疗孕妇的胎盘功能生物学指标发生了显著变化。然而, 产科并发症的发生率似乎尚不存在剂量依赖性。

The Chinese abstracts are translated by Prof. Dr. Xiangyan Ruan and her team: Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.

Keywords:

• Hypothyroidism in pregnancy
• placental function
• levothyroxine
• uterine artery pulsatility index

Disclosure statement

The authors report no conflicts of interest.