Foeto-placental parameters in normal pregnancy and factors affecting them

The aim of this study was to evaluate foeto-placental (F/P) parameters, namely foetal birth weight, placental weight (PW) and F/P weight ratio, in normal pregnancy and factors affecting them.

A retrospective study was conducted on labour ward data obtained over a period of 3 years (2015-2017). Only deliveries above 28-week gestational age which met other selection criteria were included in the study. Their sociodemographic parameters, PW, foetal birth weight, foetal outcome and Apgar scores were extracted from the delivery registers. The F/P weight ratio was calculated from the values obtained. All data collected were subjected to statistical analysis using SPSS version 20.

The mean age ± standard error of mean of parturient was 31.84 ± 0.18 years. A larger proportion, 1455 (80.7%) of the women were booked. The mean gestational age ± standard deviation at delivery was 37.81 ± 2.72 weeks. Foetal weight (FW), PW and F/P weight ratio rise progressively with advancing gestational age in normal pregnancy, the FW rising faster than the placenta which gains weight slowly. The F/P ratio rises steadily initially and then abruptly from 42-week gestational age as the foetus outgrows the placenta, after which there is a sharp decline from 43-week gestational age. FW, PW and F/P ratio are significantly affected by gestational age and booking status (P = 0.000). Parity and foetal sex were found to have significant influence on FW alone (P = 0.026 and P = 0.000, respectively).

This study clarifies the need to avoid undue prolongation of pregnancy beyond 42 weeks to avert adverse consequences which may be related to the differential growth in the foetus and placenta.