Maternal chrononutrition during pregnancy and the composition of intestinal and placental microbiota

Background: Disrupted feeding timing may alter microbiota profiles and contribute to metabolic disturbances. This study aimed to investigate the impact of maternal chrononutrition during pregnancy on maternal gut and placental microbiota. Methods: This study was conducted between April 2022 and February 2023 at Erciyes University Faculty of Medicine Hospitals and Kayseri Private Dünyam Hospital in Kayseri, Türkiye, among healthy pregnant women with predominantly daytime feeding (pDT, n = 10) or predominantly nighttime feeding (pNT, n = 10). A questionnaire was administered, and three-day food consumption diaries were recorded at both 20–26 and 32–36 weeks of gestation. Fecal samples were collected at 32–36 weeks of gestation, and placental samples were collected at birth and stored at -80 °C until analysis. Results: Although total daily energy intake at both gestational periods (20–26 and 32–36 weeks) was similar between the groups, gestational weight gain was greater in the pNT group [16.30 (5.25) kg] than in the pDT group [11.90 (3.41) kg] (p = 0.039). Compared with the pDT group, the Firmicutes: Bacteroidetes ratio was higher in the maternal gut microbiota of the pNT group. Furthermore, Bacilli, Lactobacillales, Lactobacillaceae, and Lactobacillus were significantly more abundant in the pDT group than in the pNT group (p < 0.05). The intestinal and placental microbiota of the pDT and pNT groups had similar alpha and beta diversity. Conclusions: Our findings suggest that predominantly daytime or nighttime feeding during pregnancy may influence the composition of maternal gut and placental microbiota. These microbiome alterations may have potential implications for maternal and infant health; however, larger longitudinal studies are needed to clarify their long-term relevance, including possible links with fetal programming.