Serum placental growth factor and soluble fms‐like tyrosine kinase 1 at mid‐gestation in healthy women: Association with small‐for‐gestational‐age neonates

Aim This study was performed to determine the associations between serum placental growth factor (PlGF) and soluble fms‐like tyrosine kinase 1 (sFlt‐1) levels at mid‐gestation with the risk of small‐for‐gestational‐age (SGA) neonates born at gestational week (GW) ≥ 36 in healthy women. Methods PlGF and sFlt‐1 concentrations were determined at GW 24–27 in 183 women with births at GW ≥ 36, but without gestational diabetes mellitus and hypertension. Results Thirteen (7.1%) SGA neonates were born. Median (range) GW at blood sampling was similar between women with and without SGA (25 [24–25] and 24 [24–27], respectively, P = 0.671). Pre‐pregnancy body mass index (BMI) and PlGF levels were significantly lower in women with than without SGA, while sFlt‐1 levels and sFlt‐1 : PlGF ratio (sFlt‐1/PlGF) did not differ significantly between the two groups. PlGF and sFlt‐1/PlGF, but not BMI or sFlt‐1, showed significant correlations with birthweight z ‐score; the correlation was positive for PlGF and negative for sFlt‐1/PlGF. Women with PlGF level < 10th percentile and those with sFlt‐1/PlGF level > 90th percentile showed significantly increased risk of SGA compared to those with respective counterpart characteristics; relative risk was 3.8 (95% confidence interval, 1.3–11.3; 21% [4/19] vs 5.5% [9/164]) for PlGF and 7.9 (95% confidence interval, 3.0–20.8, 33.3% [6/18] vs 4.2% [7/165]) for sFlt‐1/PlGF. Conclusion Maternal PlGF and sFlt‐1/PlGF determined during GW 24–27 were associated with the risk of SGA neonates born at GW ≥ 36, even in women with uncomplicated pregnancies.