Determination of placental growth factor (PlGF) levels in healthy pregnant women without signs or symptoms of preeclampsia

Objective: To identify a reference range for placental growth factor (PlGF) in normotensive women without symptoms or signs of preeclampsia. Study design: Comprising the study cohort were 247 term pregnancies without preeclampsia or adverse neonatal outcomes from 16 sites in the US and Canada. Serial plasma samples were collected in 6 gestational age (GA) intervals between 20 + 0 and 40 + 0 weeks. Non-parametric percentiles of the distribution of PlGF were estimated in each GA interval and a parametric model was developed to describe the distribution of PlGF as a continuous smooth function of GA (from 20 to 40 weeks) in normal healthy pregnancy. Demographic and clinical factors influencing PlGF levels were also examined. Results: There were 1366 evaluable samples collected from 247 subjects (242, 238, 226, 223, 222, and 215 samples in each GA interval, 20-24, 24-29, 29-32, 32-35, 35-37, and 37-40 weeks, respectively). The 5th percentile of PlGF was 76.4, 141.1, 139.3, 65.5, 31.7, and 23.4 pg/mL in each respective GA interval. The distribution of PlGF is approximately log normal with parameters that vary continuously as a function of GA. PlGF distribution is weakly dependent on maternal age, race/ethnicity, parity, and maximum systolic blood pressure (taken between weeks 20 and 24). Although statistically significant, these factors did not modify PlGF levels by more than ±15%. Conclusion: These data provide a valid reference range for PlGF in normal pregnancy.