Adaptations in Gastrointestinal Nutrient Absorption and its Determinants During Pregnancy in Monogastric Mammals: A Scoping Review.

Context: Pregnancy increases nutrient demand, but how nutrient uptake and its determinants adapt to facilitate this is unclear.

Objective: This review aimed to identify and characterize evidence and evidence gaps regarding changes in gastrointestinal nutrient absorption and its determinants during pregnancy in monogastric mammals.

Data sources: A scoping review of peer-reviewed sources was conducted across PubMed, Scopus, Web of Science, Embase, and ProQuest (theses and dissertations) databases.

Data extraction: Data extracted included species, pregnancy stages and outcomes. Where sufficient data for a given outcome was available, relative values were summarized graphically or in tables, to allow comparison across pregnancy stages and/or small intestine regions. Searches identified 26 855 sources, of which only 159 were eligible. Mechanistic studies were largely restricted to rodents, and most compared non- and late-pregnant groups, with fewer studies including early- or mid-pregnant groups.

Data analysis: During pregnancy, there is some evidence for greater capacity for glucose uptake but unchanged amino acid uptake, and good evidence for increased uptake of calcium, iron, and zinc, and slower gastrointestinal passage of nutrients. The available evidence indicates that acute glucose uptake, gastric emptying, and the activities of sucrase, maltase, and lactase do not change during pregnancy. Gaps in the knowledge include the effects of pregnancy on uptake of specific amino acids, lipids, and most minerals and vitamins.

Conclusion: The results indicate that the gastrointestinal tract adapts during pregnancy to facilitate increased nutrient absorption. Additional data is required in order to assess the underlying mechanisms for and impacts on the absorption of many nutrients, as well as to determine the timing of these adaptations.