INFLUENCE OF MATERNAL HEIGHT ON BIRTHWEIGHT CLASSIFICATION AND SEVERE ADVERSE PERINATAL OUTCOMES IN SINGLETON AT TERM BIRTHS IN THE NETHERLANDS

Abstract

Background: An accurate birthweight classification is important to prevent severe adverse perinatal outcomes (SAPO). Neonates who are small for gestational age (SGA, p≤10) or large for gestational age (LGA, p90) have a higher risk for SAPO. Aim: To assess the association between maternal height and birthweight in low-risk pregnancies and to investigate the effect of maternal height on the classification of birthweight as SGA and LGA. Secondly, to investigate whether maternal height has a predictive value for the risk of SAPO. Method: An observational study using prospectively precollected data from the IRIS study was conducted (n=6970). The influence of maternal height on birthweight and SAPO was analysed. The number of neonates classified as SGA and LGA was calculated. Subsequently, the changes in classification from SGA and LGA to appropriate for gestational age (AGA) were calculated. Results: A significant association was found between maternal height and birthweight (p<.001) and maternal height and SAPO (p=.023). Shorter and taller women had a higher risk for SAPO. A logistic regression with maternal height squared showed that this curvilinear effect was not significant (p=.062). The incidence of SGA was 7.2% (decreasing from 17.9% to 2.9% in the shortest to tallest height categories) and LGA was 9.5% (increasing from 2.7% to 15.5%). A shift in classification was found for 18.1% of the SGA and 17.5% of the LGA neonates when controlling for maternal height. Conclusion: Maternal height is significantly associated with birthweight and SAPO. Customised birthweight charts based on maternal height changes the classification of around one in five SGA or LGA neonates at term. Recommendations: Validation studies to assess the predictive value of a customised birthweight chart based on maternal height on SAPO.