Researchers have discovered how and why women’s intestines change during pregnancy and breastfeeding.
- The intestines almost double in size during pregnancy and breastfeeding.
- Researchers have discovered that the culprit is the RANK/RANK-Ligand system which is controlled by sex and pregnancy hormones.
- The intestines seem to return to their original size and structure when breastfeeding is stopped.
Becoming a mother takes a toll… literally. An international study, led by the Medical University of Vienna, found that the intestines of pregnant and breastfeeding women changed, leading to a doubling of their surface area and structural reorganization. It was published in the journal Nature on December 4, 2024.
Pregnancy, breastfeeding: the intestines double in size to ensure the baby’s good health
To better understand the impact of pregnancy on the digestive system, the international team studied pregnant mice as well as intestinal organoids. That is to say small 3D biological structures reproducing the functions of the intestines. By analyzing these different elements, researchers understood that the RANK receptor/RANK-Ligand protein (RANK/RANKL) system causes the surface area of the small intestine to increase during pregnancy and breastfeeding. This “massive expansion”controlled by sexual and pregnancy hormones, increases the molecular machinery for the absorption of sugar, proteins and fats. There is also a profound architectural change in the intestinal villi. The latter appears to lead to a slowing of food flow, thereby maximizing nutrient absorption. Another observation by researchers: the intestines return to their initial size and structure when breastfeeding is stopped.
The role of the RANK/RANKL system in the intestine during pregnancy and breastfeeding was confirmed by the study of mice genetically modified to not have it. These animals had much lower villi expansion than the others during their gestation and lactation period.
This part of the experiment revealed that the intestinal changes that begin during pregnancy are essential to ensure good nutrition for babies. “Our study shows that the alteration of this intestinal expansion by the absence of the RANK/RANKL system during pregnancy modifies the milk of breastfeeding mothers. This results in a reduction in the weight of babies and long-term transgenerational metabolic consequences”specifies lead author Masahiro Onji in a press release. “Mothers need to eat for themselves and their babies. These new studies provide for the first time a molecular and structural explanation of how and why the gut changes to adapt to mothers’ increased demand for nutrients, which which is probably the case in all pregnant and lactating mammals”adds the head of the study, Josef Penninger.
This discovery could lead to treatments against intestinal tumors
“By identifying the RANK/RANKL system as the driving force behind intestinal adaptation during pregnancy and lactation, our study contributes to a deeper understanding of biological processes that are of fundamental importance to evolution and health human”explains Josef Penninger from the Medical University of Vienna.
Furthermore, this discovery could also open a new avenue of research for the treatment of intestinal tumors. “We also discovered that this system, via stem cells, can directly affect tumors in the intestine. Perhaps we can learn from pregnant and lactating women to reprogram this system in a reversible way to develop new treatments and a better understanding of intestinal cancer or intestinal regeneration”warns the specialist.
