Maternal Thyroid Function and Biochemical Markers of Placental Function in Early Pregnancy

Objective

A link between maternal thyroid function and the placental biomarkers, soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF), has been brought forward. This study aimed to describe their association in early pregnancy.

Design

Retrospective cohort study.

Participants

Eight hundred and fifty-eight pregnant women from the North Denmark Region, 2013, with blood samples drawn in early pregnancy.

Measurements

Thyroid-stimulating hormone (TSH), free thyroxine (fT4), thyroid-peroxidase antibodies (TPO-Ab), thyroglobulin antibodies (Tg-Ab) (ADVIA Centaur XPT, Siemens Healthineers), sFlt-1 and PlGF (Kryptor Compact, ThermoFisher Scientific) were measured. The association between maternal TSH and fT4 and percentile (pc) levels of sFlt-1 and PlGF (< 25th pc, 25–75th pc, > 75th pc) was evaluated using regression analysis and reported as adjusted beta coefficient (aβ). The frequency of maternal thyroid autoantibodies (TPO-Ab > 60 U/mL or Tg-Ab > 33 U/mL) by pc levels of sFlt-1 and PlGF was compared using chi-squared test.

Results

Higher levels (> 75th pc) of sFlt-1 associated with lower TSH (aβ 0.62, 95% CI: 0.51–0.76) and higher fT4 (aβ 1.03, 95% CI: 1.01–1.05). Higher levels of PlGF associated with lower TSH (aβ 0.82, 95% CI: 0.69–0.98), but not with levels of fT4 (aβ 1.00, 95% CI: 0.97–1.02). No association with maternal thyroid autoantibodies was found (TPO-Ab: sFlt-1: p-value 0.5 and PlGF: p-value 0.1; Tg-Ab: sFlt-1: p-value 0.7 and PlGF: p-value 0.1).

Conclusions

In a large cohort of Danish pregnant women, higher levels of sFlt-1 and PlGF associated with maternal thyroid function in early pregnancy, while there was no association with maternal thyroid autoantibodies.