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

Area of Science:

• Reproductive Endocrinology
• Maternal-Fetal Medicine
• Obstetrics

Background:

• Thyroid dysfunction in pregnancy requires management with levothyroxine.
• Euthyroid status is crucial for optimal pregnancy outcomes.
• Levothyroxine's impact on placental function markers needs further investigation.

Purpose of the Study:

• To compare placental function markers (PAPP-A, UtA PI) in euthyroid pregnant women on levothyroxine versus uncomplicated pregnancies.
• To evaluate the effect of varying levothyroxine dosages on pregnancy outcomes.
• To assess obstetric complication frequencies in relation to levothyroxine use and dosage.

Main Methods:

• Retrospective evaluation of 206 levothyroxine-using pregnant women and 449 controls.
• Analysis of placental function markers: pregnancy-associated plasma protein-A (PAPP-A) and uterine artery pulsatility index (UtA PI).
• Stratification of levothyroxine users into dosage groups (75, 100, 150 mcg) to assess dose-dependency.

Main Results:

• Levothyroxine users exhibited significantly lower median PAPP-A MoM (0.94 vs. 1.11) and higher median UtA PI (2.08 vs. 1.74) compared to controls.
• Median birth weight was significantly lower in the levothyroxine group (3292g vs. 3427g).
• No significant differences in PAPP-A MoM, UtA PI, or obstetric complication rates were observed among different levothyroxine dosage groups.

Conclusions:

• Euthyroid pregnant women on levothyroxine demonstrate altered first-trimester placental function markers.
• Levothyroxine use is associated with lower birth weight.
• Obstetric complication frequency does not appear to be dose-dependent on levothyroxine therapy.