Circulating free soluble fms-like tyrosine kinase-1 during late first trimester in relation with placental volume as a surrogate for trophoblastic production: a physiology study in low-risk cohort

Abstract

Background: Data on first-trimester circulating soluble fms-like tyrosine kinase-1 (sFlt-1) and ischemic placental disease is limited and conflicting. This study aimed to study its physiology in relation to trophoblastic mass as the source of production.

Methods: Low-risk (representing normal placentation) women from 11 0/7 to 13 6/7 weeks’ gestation were prospectively enrolled. Selective measurement of serum free sFlt-1 using a new automated assay from 100 eligible subjects was analyzed with gestational age, maternal weight, fetal crown-rump length (CRL), and mean uterine artery Doppler pulsatility index (PI). Placental volume (surrogate for trophoblastic mass) was estimated using 3-dimensional ultrasound and was assessed for its association with serum free sFlt-1.

Results: There was no significant association between serum free sFlt-1 and placental volume in either arithmetic (r = 0.053, p = 0.600), logarithmic (r = 0.005, p = 0.963), or quartile (p = 0.703) scale. There was a significant negative correlation between free sFlt-1 level and maternal weight (r=−0.213, p = 0.033). No significant correlation was found between free sFlt-1 level and gestational age (r = 0.007, p = 0.947), CRL (r = 0.027, p = 0.788), and uterine artery Doppler mean PI (r = 0.020, p = 0.828).

Conclusions: Lack of correlation between circulating free sFlt-1 level and placental volume suggests that trophoblasts are not its major source during first trimester with presumably physiologic placentation.

Keywords:

• Free sFlt-1
• placental volume
• preeclampsia
• serum biomarker

Disclosure statement

Tuangsit Wataganara has received travel bursary from ThermoFisher to actively participate in their sponsored lecture event. ThermoFisher supported the reagents for this study, but did not influence in drafting of proposal, conducting of the research or statistical analyzes. Kathrin Matischak, KH Chong, and Thanadech Chinsiroros from ThermoFisher and Global Biotechnology have helped editing the description of automated free sFlt-1assay methodology.

Funding

This study was supported by a fellowship research grant from Faculty of Medicine Siriraj Hospital. The authors want to thank Suchitra Pongprasobchai, RN, Prakong Chuenwattana, PhD, and the nursing staffs at Antenatal Clinic and Maternal Fetal Medicine Division for their assistance in enrollment process. Additional statistical assistance was done by Julaporn Pooliam from Department of Epidemiology, Faculty of Medicine Siriraj Hospital was highly appreciated.