Skip to main content
. Author manuscript; available in PMC: 2023 Oct 1.
Published in final edited form as: Nat Rev Gastroenterol Hepatol. 2022 Dec 16;20(4):223–237. doi: 10.1038/s41575-022-00714-7

Fig. 2 ∣. Expansion of small intestinal absorptive capacity during pregnancy and lactation.

Fig. 2 ∣

The extreme metabolic demands of pregnancy and lactation require the expansion of small intestinal absorptive capacity. a, Maximum sustained human metabolic scope (fold-increase in basal metabolic rate, BMR) versus duration of extreme endurance events flattens out at 2.5× BMR. Cumulative average metabolic scope is shown for elite cyclists over a touring season, Arctic trekking, Race Across The USA runners, and pregnancy and lactation. The sustained metabolic demands over the duration of pregnancy and lactation are equivalent to model estimates for ultramarathons and other extreme endurance events lasting 9 months or more. b, Direct changes in small intestinal mass due to feeding in lactating mice. c, Indirect changes in small intestinal mass due to increasing litter mass. Part a adapted with permission of AAAS from ref. 48, © The Authors, some rights reserved; exclusive licensee AAAS, distributed under a CC BY-NC 4.0 License (http://creativecommons.org/licenses/by-nc/4.0/). Parts b and c adapted from ref. 51, Springer Nature Limited. Part b also adapted with permission from ref. 49, The University of Chicago Press.