Food Records Show Daily Variation in Diet during Pregnancy: Results from the Temporal Research in Eating, Nutrition, and Diet during Pregnancy Study.

Background: Diet is critical for pregnant individuals and their offspring, but insight into diet during pregnancy mainly comes from questionnaires and recalls.

Objectives: To obtain detailed real-time dietary data during pregnancy to evaluate intra- and interindividual variation in intakes.

Methods: Pregnant individuals were recruited from a New York City health system December 2020-June 2023. Participants collected dietary intakes for 14 d (mean gestational weeks = 17.6) and again roughly 4 wk later (mean gestational weeks = 24.5). Participants logged each eating occasion using a smartphone and study-developed app, and wore a smartwatch capturing physiologic data.

Results: In total, 150 individuals completed ≥1 data collection round, with 134 completing both rounds. Mean daily eating window was 10.82 h, with weekends having a significantly shorter window than weekdays (P < 0.001). Eating window was correlated with energy intake (r = 0.401, P < 0.001), driven by later last eating occasions. There was high intraindividual variation in macro- and micronutrient intakes [intraclass correlation coefficient (ICC), range 0.11-0.40] and food type (ICC range: 0.08-0.34), and differences between weekdays and weekends (less protein and micronutrients on weekends). Few participants' mean intakes met daily recommended dietary allowances for key micronutrients (under 15% for iron, magnesium, vitamin D, and vitamin E; under 30% for calcium, folate, zinc, and vitamin A).

Conclusions: Dietary intakes varied substantially within and between individuals, and mean nutrient intake estimates did not capture nutrient adequacy for individuals or populations. Future work that examines individual daily dietary intakes throughout pregnancy among diverse populations is needed.