Implications of a high placental ratio in pregnancies with appropriate-for-gestational age neonates

To determine the relationship between the placental weight to birth weight ratio (placental ratio) with maternal pre-pregnancy weight, gestational weight gain, and neonatal outcome in non-diabetic pregnancies resulting in appropriate-for-gestational age (AGA) infants.

A retrospective study was performed on 593 patients with singleton pregnancies, normal results in the 75-gram oral glucose tolerance test and who delivered AGA newborns within a 1-year period. The patients were categorized into high placental ratio (> mean +1 SD based on previous data, n = 113 or 19.1%) and normal ratio groups for the comparison of maternal and neonatal anthropometric parameters.

The high placental ratio group had a higher pre-pregnancy weight, body mass index, placental weight, and incidence of low Apgar score, but decreased absolute and percentage gestational weight gain, gestational age, and birth weight. After controlling for pre-pregnancy weight and gestational age, only the correlation between placental weight and percent weight gain remained significant.

Our finding suggests that a high placental ratio can identify AGA newborns who are disproportionately small relative to maternal size, and may reflect some form of fetal growth impairment.