OBJECTIVETo identify a reference range for placental growth factor (PlGF) in normotensive women without symptoms or signs of preeclampsia.STUDY DESIGNComprising 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+0weeks. 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 40weeks) in normal healthy pregnancy. Demographic and clinical factors influencing PlGF levels were also examined.RESULTSThere 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 37-40weeks, respectively). The 5th percentile of PlGF was 76.4, 141.1, 139.3, 65.5, 31.7, and 23.4pg/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%.CONCLUSIONThese data provide a valid reference range for PlGF in normal pregnancy.
