Gestational age and birth weight centiles of singleton babies delivered normally following spontaneous labor, in Southern Sri Lanka

K Attanayake,M Goonewardene,S Munasinghe,L Sanjeewa,I Sandeepani,P Widanapathirana

doi:10.4038/cmj.v63i1.8631

Abstract

To estimate the gestational age and birth weight centiles of babies delivered normally, without any obstetric intervention, in women with uncomplicated singleton pregnancies establishing spontaneous onset of labour. Consecutive women with uncomplicated singleton pregnancies, attending the Academic Obstetrics and Gynecology Unit of the Teaching Hospital Mahamodara Galle, Sri Lanka, with confirmed dates and establishing spontaneous onset of labor and delivering vaginally between gestational age of 34 - 41 weeks, without any obstetric intervention , during the period September 2013 to February 2014 were studied. The gestational age at spontaneous onset of labor and vaginal delivery and the birth weights of the babies were recorded. There were 3294 consecutive deliveries during this period, and of them 1602 (48.6%) met the inclusion criteria. Median gestational age at delivery was 275 days (range 238-291 days, IQR 269 to 280 days) and the median birth weight was 3000 g (range1700g - 4350g; IQR 2750-3250g). The 10th, 50th and 90th birth weight centiles of the babies delivered at a gestational age of 275 days were approximately 2570g, 3050g and 3550g respectively. The median gestational age among women with uncomplicated singleton pregnancies who established spontaneous onset of labor and delivered vaginally, without any obstetric intervention, was approximately five days shorter than the traditionally accepted 280 days. At a gestational age of 275 days, the mean birth weight was approximately 3038g and the 50th centile of the birth weight of the babies delivered was approximately 3050g.

Highlights

Pregnant women and their partners are anxious to know the “estimated date of delivery” (EDD)
In a study carried out in Washington DC, 56% of women accurately recalled their menstrual dates; 74% were within 1 day, and 81% were within 2 days [4]
For gestational age between nine to fourteen weeks, if the discrepancy between the estimates by last menstrual period (LMP) and estimates by crown-rump length were less than seven days, the gestational age estimate obtained by the LMP was considered to be correct

Summary

Introduction

Pregnant women and their partners are anxious to know the “estimated date of delivery” (EDD). The combination of a calculation of 280 days from the first day of the last menstrual period (LMP) and a standardised, ultrasound crown-rump length measurement between 9-14 weeks, plotted on an appropriate chart, is considered the best method to confirm gestational age [2,3]. In a study carried out in Washington DC, 56% of women accurately recalled their menstrual dates; 74% were within 1 day, and 81% were within 2 days [4]. Ultrasound estimation of gestational age assumes that all fetuses with a given measurement will have the same gestational age. This is not a good scientific argument because the inherent biological variability, whether it is small or large, should be considered.

Methods

Results

Discussion

Conclusion