Placenta/birthweight ratio and perinatal outcome: a retrospective cohort analysis.

OBJECTIVE: The placenta weight/birthweight (PW/BW) ratio has been shown to be associated with certain long-term fetal outcomes; however, its association with short-term outcomes has not received much attention. Our aim was to assess the correlation between the PW/BW ratio and short-term adverse obstetrics outcomes in full-term, appropriate-for-gestational-age (AGA) newborns.
DESIGN: Retrospective cohort study analysis using data from the McGill Obstetrical and Neonatal Database.
SETTING: McGill University Health Centre in Montreal Canada. POPULATION: AGA neonates.
METHODS: Three groups of full-term AGA neonates were created, according to their PW/BW ratio (high, normal and low), to be compared. Our primary outcome was the admission rate to the neonatal intensive care unit (NICU), and secondary outcomes included an Apgar score < 7 at 5 minutes, cord PH < 7.0, cord base excess (BE) ≤ 12, respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), occurrence of apnoea episodes, breech presentation at delivery, caesarean section rate and status in discharge home. A logistic regression model was instituted to investigate the predictors for adverse obstetrics outcomes. MAIN OUTCOME MEASURE: Admission to the NICU.
RESULTS: Compared with the group with normal PW/BW ratios, the high PW/BW ratio group was associated with increased rates of admission to the NICU, of Apgar scores < 7 at 5 minutes, of breech presentation and caesarean section. On the contrary, the low PW/BW ratio group showed decreased rates of NICU admission, breech presentation and caesarean section.
CONCLUSIONS: A high PW/BW ratio is significantly correlated with short-term adverse perinatal outcomes. This ratio may be used as a new and simple warning sign to predict the possibility of short-term health risks for newborns.