This longitudinal, prospective, multicenter observational cohort study investigates the associations between maternal nutritional status-assessed using the first trimester SIMPLE score and pregestational BMI-and fetal growth trajectories and velocity, as proxies for intrauterine development. Healthy women with singleton pregnancies undergoing first trimester screening were enrolled. Adherence to a healthy lifestyle was evaluated using the SIMPLE score, categorizing participants into low (<6) and high (≥6) adherence groups. Fetal growth parameters - including biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), estimated fetal weight (EFW)- were assessed during second and third trimester ultrasounds, and birth outcomes were recorded. Multi-adjusted linear mixed models examined associations between SIMPLE score groups, individual score items, pregestational BMI, and fetal growth, with analyses stratified by fetal sex. Out of 938 enrolled women, 109 (11.6%) were classified as the low adherence group. Multi-adjusted linear mixed models showed that low adherence was associated with decreased EFW acceleration from the second to the third trimester. Stratification by fetal sex confirmed the association only among male fetuses. Analysis of pregestational BMI and individual SIMPLE score items revealed significant positive associations between pregestational BMI, AC, and EFW growth velocity, and a negative association between first trimester hemoglobin [>110 g/l] and EFW growth velocity. Overall, these findings confirm the clinical utility of the SIMPLE score, demonstrating significant associations with intrauterine growth trajectories and velocity, independent of other markers of nutritional status (e.g., pregestational BMI).
Keywords: SIMPLE score; abdominal circumference; estimated fetal weight; fetal growth velocity; fetal sex; maternal hemoglobin; maternal nutrition; pregestational BMI; prenatal growth trajectory.