Circulating soluble fms-like tyrosine kinase-1 and placental growth factor from 10 to 40 weeks' pregnancy in normotensive women

Introduction: Circulating soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) are potential markers for preeclampsia. The objective was to construct and analyse the reference ranges of serum levels of sFlt-1 and PlGF throughout the course of pregnancy in low-risk Thai pregnant women. Methods: We enrolled 110 low-risk, Thai women singleton pregnancy from 10 to 40 gestational weeks. Serum concentrations of sFlt-1 and PlGF were measured with an automated assay. The reference ranges of serum levels of sFlt-1, PlGF and sFlt-1/PlGF ratio were constructed and assessed for possible correlations with gestational age, maternal factors [age, parity, tobacco use, artificial reproductive technologies (ARTS) and body mass index (BMI)], and pregnancy outcomes (gestational age at delivery, development of preeclampsia, neonatal birth weight and placental weight). Results: None of the subjects developed preeclampsia. Serum sFlt-1 concentrations significantly elevated from 20 to 40 gestational weeks (P = 0.003). Significant elevation and dropping of serum PlGF levels and sFlt-1/PlGF ratios were observed at 10 to 29 and 30 to 40 weeks of gestation, respectively (P < 0.001). There was an inversed correlation between serum PlGF levels at 20 to 29 gestational weeks and neonatal birth weights (r = -0.48, P < 0.05). There were no associations between serum levels of sFlt-1, PlGF, or sFlt-1/PlGF ratios and maternal BMI, gestational age at delivery, or placental weight (P > 0.05). Effects from parity, smoking and ARTS were inconclusive. Conclusion: Robust change of serum PlGF levels suggests for its broader clinical application compared to sFlt-1. Prediction of preeclampsia using serum analytes may be gestational period specific.