Exposure to ultra-processed foods during pregnancy and ultrasound foetal growth parameters.

Periconceptional maternal ultra-processed food (UPF) consumption impairs embryonic growth. Impacts of exposure to UPF on distinct components of foetal growth in late pregnancy are unknown. We investigated the influence of frequency of UPF consumption during pregnancy on foetal head circumference (HC), abdominal circumference (AC), and femur length (FL). This study included 417 live-born singleton pregnancies prospectively followed-up since the antenatal period in the MINA-Brazil Study, with an available ultrasound scan at >24 gestational weeks. Frequency of food groups consumption in the previous month was categorised as no/monthly, weekly, or daily. Ultrasound scans were conducted at 27.8 (SD: 1.7) gestational weeks. HC, AC, and FL z-scores were calculated for gestational age using the INTERGROWTH-21 st Project standards. Simultaneous-quantile regression models were fitted at the 10 th , 50 th , and 90 th percentiles of the distribution of each ultrasound parameter according to UPF consumption, with adjustment for potential confounders. Participants were aged on average 24.7 (SD: 6.5) years, 44.8% were primiparous, and 26.9% and 24.9%, respectively, had weekly and daily UPF consumption. Compared to no/monthly intake, daily UPF consumption impaired HC across its distribution, with significant effect sizes varying from -0.24 to -0.40 z-score. Weekly UPF consumption decreased HC at the 90 th percentile by -0.39 z-score (95% CI: -0.78, -0.01) and FL at the 50 th percentile by -0.32 z-score (95% CI: -0.60, -0.04). No association was noted with AC. Frequency of UPF consumption was negatively associated with skeletal components of foetal growth in late pregnancy. Infant body composition may benefit from healthy food practices since pregnancy.