Dinner Timing During Pregnancy Linked to Epigenetic Changes in the Placenta

It is not only what is eaten during pregnancy that matters, but also when it is eaten. This was the starting hypothesis of a chrononutrition study conducted by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the ”la Caixa” Foundation and published in Molecular Nutrition & Food Research. The researchers set out to take a first step in determining whether meal timing during pregnancy has any impact on placental function. The findings show that, among all daily meals, dinner is the only one whose timing is associated with changes in DNA methylation in the placenta.

DNA methylation involves the addition of small chemical markers (methyl groups) to DNA, which can switch genes on or off. It is part of epigenetics, a set of mechanisms that regulate gene activity without altering the DNA sequence. In the placenta, DNA methylation provides an indication of how gene activity is regulated in this organ, which is essential for fetal development.

“Later meal timing and lower meal frequency have been linked to factors such as gestational weight gain and gestational diabetes,” explains Joana Llauradó Pont, predoctoral researcher at ISGlobal and first author of the study. To explore its effects on placental epigenetics, the team conducted an epigenome-wide association study (EWAS) involving 389 women from the Barcelona Life Study (BiSC) cohort. Information on diet and chrononutrition habits was collected at week 20 of pregnancy, and placental tissue samples were obtained after delivery to analyse DNA methylation using “Illumina EPIC” technology.

“We focused on five key aspects,” adds Llauradó Pont, “the timing of the first and last meals, the duration of the overnight fast, the number of meals, and variability in meal timing.”

Dinner timing: a habit linked to epigenetic changes

The study identified changes in placental DNA methylation (hypo- or hypermethylation) mainly associated with the timing of the last meal of the day. Although this initial research did not establish an optimal dinner time, it did find that variations in this timing were linked to changes in the regulation of several genes, some involved in pregnancy-related biological processes. For instance, one plays a role in cholesterol metabolism, which is crucial for fetal development. Others are involved in the formation of blood vessels, the regulation of cell growth, and the DNA damage response. Signals were also observed in genes related to programmed cell death and the immune system.

“The timing of the last meal may act as a relevant time cue for the maternal body and, through epigenetic mechanisms, influence biological processes during pregnancy,” explains Camille Lassale, the study’s coordinator. “While a causal relationship cannot be established, these findings suggest that when food is consumed may modulate placental function and potentially have implications for fetal development.”

This study represents an initial step towards understanding how meal timing may influence placental function and opens the door to future research to clarify the specific role of eating schedules, why dinner stands out compared to other dietary habits, and which time windows may be associated with greater benefits during pregnancy.

Circadian rhythms and chrononutrition

Circadian rhythms are biological cycles of around 24 hours that regulate physiological and behavioural functions. They are controlled by internal “clocks”, such as the suprachiasmatic nucleus in the hypothalamus, which responds to light and darkness. There are also clocks in organs such as the liver and muscles, which are sensitive to signals like food intake. For this reason, meal timing influences the circadian system, and irregular eating patterns can affect health. Chrononutrition examines the relationship between diet, circadian rhythms, and health.