Maternal First Trimester SIMPLE Nutritional Score and Intrauterine Fetal Growth Trajectory: a Prospective Multicenter Italian Study (SIMPLE Study)

Introduction: Unhealthy dietary patterns increase the risk of adverse pregnancy outcomes, with short- and long- term health effects. This study aimed to evaluate the associations between first trimester maternal nutrition and lifestyle and fetal growth trajectories. Methods: Healthy women with singleton pregnancies were enrolled (11+0 - 13+6 weeks) in a multicenter Italian prospective observational cohort between Jan 19 - Sept 23. The SIMPLE score (SS, 0-10) assessed the adherence to a healthy diet and lifestyle at enrollment. Participants were divided in unhealthy (SS<6) and healthy (SS>6) groups. Abdominal circumference (AC) and estimated fetal weight (EFW) were calculated during 2nd - 3rd trimester ultrasounds. Multi-adjusted linear mixed models were performed to investigate the associations between the SS and longitudinal fetal growth measurements, including adjustment for pregestational BMI and gestational weight gain. Results: 938 women were enrolled, including 109 (11.6%) in the unhealthy group. The unhealthy group was associated with a significantly slower EFW gain from the second to the third trimester (B=-0.028, p=0.015). This effect was more pronounced among male fetuses, showing decreased EWF (B=-0.053, p=0.002) and AC (B=-0.053, p=0.032) trajectories between the second and third trimesters. The analysis of individual SS components showed that first trimester hemoglobin concentration 110 g/dL were significantly associated with reduced EWF gain during pregnancy (average absolute difference of 0.082 g, p=0.001). Conclusions: Suboptimal nutritional adherence was associated with a slower EFW gain and AC trajectory during pregnancy, particularly among male pregnancies. These results suggest that the SS could serve as an early screening tool to identify women at risk of suboptimal fetal growth due to poor nutrition, emphasizing the need for early targeted nutritional interventions to optimize pregnancy outcomes.