Assessing fetal growth in Africa: Application of the international WHO and INTERGROWTH-21st standards in a Beninese pregnancy cohort.

Emmanuel Yovo,Auguste Degbe,Ghyslain Mombo-Ngoma,Olaiitan T Ladikpo,Achille Massougbodji,William Atade,Manfred Accrombessi,Valérie Briand,Murielle Mehoba,Barbara Heude,Jennifer Zeitlin,Nikki Jackson,Alice Hocquette,Gino Agbota,Nadine Fievet

doi:10.1371/journal.pone.0262760

Abstract

Fetal growth restriction is a major complication of pregnancy and is associated with stillbirth, infant death and child morbidity. Ultrasound monitoring of pregnancy is becoming more common in Africa for fetal growth monitoring in clinical care and research, but many countries have no national growth charts. We evaluated the new international fetal growth standards from INTERGROWTH-21st and WHO in a cohort from southern Benin. Repeated ultrasound and clinical data were collected in women from the preconceptional RECIPAL cohort (241 women with singleton pregnancies, 964 ultrasounds). We modelled fetal biometric parameters including abdominal circumference (AC) and estimated fetal weight (EFW) and compared centiles to INTERGROWTH-21st and WHO standards, using the Bland and Altman method to assess agreement. For EFW, we used INTERGROWTH-21st standards based on their EFW formula (IG21st) as well as a recent update using Hadlock's EFW formula (IG21hl). Proportions of fetuses with measurements under the 10th percentile were compared. Maternal malaria and anaemia prevalence was 43% and 69% respectively and 11% of women were primigravid. Overall, the centiles in the RECIPAL cohort were higher than that of INTERGROWTH-21st and closer to that of WHO. Consequently, the proportion of fetuses under 10th percentile thresholds was systematically lower when applying IG21st compared to WHO standards. At 27-31 weeks and 33-38 weeks, respectively, 7.4% and 5.6% of fetuses had EFW <10th percentile using IG21hl standards versus 10.7% and 11.6% using WHO standards. Despite high anemia and malaria prevalence in the cohort, IG21st and WHO standards did not identify higher than expected proportions of fetuses under the 10th percentiles of ultrasound parameters or EFW. The proportions of fetuses under the 10th percentile threshold for IG21st charts were particularly low, raising questions about its use to identify growth-restricted fetuses in Africa.

Highlights

Fetal growth restriction (FGR), or poor growth of a fetus during pregnancy, is associated with an increased risk of infant mortality and morbidity at birth and in childhood [1,2,3]
We modelled fetal biometric parameters including abdominal circumference (AC) and estimated fetal weight (EFW) and compared centiles to INTERGROWTH-21st and World Health Organization (WHO) standards, using the Bland and Altman method to assess agreement
The proportion of fetuses under 10th percentile thresholds was systematically lower when applying INTERGROWTH21st standards based on their EFW formula (IG21st) compared to WHO standards

Summary

Introduction

Fetal growth restriction (FGR), or poor growth of a fetus during pregnancy, is associated with an increased risk of infant mortality and morbidity at birth and in childhood [1,2,3]. Because defining and identifying FGR is difficult, small-for-gestational age (SGA) is commonly used as a proxy. SGA is defined as a fetal weight or birthweight below the 10th centile for a given gestational age (GA) according to a reference chart [6, 7]. Fetal growth restriction is a major complication of pregnancy and is associated with stillbirth, infant death and child morbidity. Ultrasound monitoring of pregnancy is becoming more common in Africa for fetal growth monitoring in clinical care and research, but many countries have no national growth charts. We evaluated the new international fetal growth standards from INTERGROWTH-21st and WHO in a cohort from southern Benin

Objectives

Methods

Results

Conclusion