Patterns of Fetal Growth based on Ultrasound Measurement and its Relationship to Small‐for‐Gestational Age at birth in Vietnam

Abstract

Small‐for‐gestational age (SGA) is a global public health concern with important short‐ and long‐ term consequences. Identifying the timing of growth faltering is critical for the prevention of SGA. This study aims to examine patterns of fetal growth and the use of ultrasound measurements in predicting SGA at birth. We used ultrasound and birth data (n=1,412) that were collected in a randomized controlled trial evaluating pre‐conception micronutrient supplements on maternal and child health outcomes in Vietnam (PRECONCEPT). Biparietal diameter (BPD), head (HC) and abdominal circumference (AC) and femur length (FL) were compared with the INTERGROWTH 21st fetal growth standards. SGA was defined as birthweight <10th percentile. Growth faltering began around mid‐pregnancy and continued through delivery. The timing varied by measurement and began earlier for BDP and AC (at 20 w) compared to HC and FL (later than 30 w). Infants born SGA had lower Z‐score in all measures as early as 14 weeks. Ultrasound measures <10 percentile were predictive of increased odds of SGA at birth: AC had the largest effects (OR: 5.5, 95% CI: 3.6, 8.5), followed by FL (OR: 3.7, 95% CI: 2.6, 5.2), BP (OR: 3.5, 95% CI: 2.3, 5.5), and HC (OR: 3.4, 95% CI: 2.3, 5.1). In conclusions, among infants born small fetal growth faltering begins in early gestation. Prenatal growth retardation is a key predictor of SGA at birth. Early detection of growth faltering is important for implementing interventions to prevent SGA and its consequences. Supported by the Mathile Institute and the Micronutrient Initiative.