Maternal obesity and pregnancy: a risk for the mother and the child

According to a recent study, unborn babies might form their intestinal flora in their mother’s wombs and inherit the same metabolic tendencies.


Excess weight is a danger to the mother herself, but is also a threat to the fetus: the intestinal bacteria produce less folate, this famous vitamin B9 recommended even before pregnancy to prevent congenital malformations such as spina bifida, a serious abnormality of the vertebral column. It also has a negative impact on the birth process, with more complicated deliveries: birth by cesarean section, before term, and even neonatal death.

The uterus is not sterile

The impact of the maternal intestinal flora might go much further according to the results of very recent studies, which question the hypothesis of a fetus immersed in a sterile uterus. Researchers were able to detect bacterial DNA in the amniotic fluid, placenta, umbilical cord and meconium (the first stools of the fetus), a sign of in utero “colonization” by the intestinal bacteria of the mother–and perhaps those of the skin, the mouth, the respiratory tract. The exact sources are not yet fully known. This transmission of intestinal flora is therefore thought to precede the already recognized transmission of vaginal flora during delivery. If the mother is obese, the unborn baby might therefore be exposed to an “obesogenic” intestinal microbiota and be predisposed to the same metabolic burden (excess weight, type 2 diabetes, cardiovascular diseases...).

Prebiotic prevention

Pregnant women who are overweight would therefore be well advised to take care of their intestinal bacteria. Taking probiotics during pregnancy and up to six months post-partum would allow them not only to improve their diabetes and reduce their body fat, but would also limit their baby’s weight gain. The optimal probiotic strains have not yet been identified. But while waiting, mothers can count on prebiotic fiber* during their pregnancy and their breastfeeding period: these undigested plant fibers promote the growth of beneficial bacteria, reduce the risk of obesity and even make the children more resilient to a diet high in fat and sugar. In short, an early form of education of the microbiota.


*Fibers found particularly in chicory, wheat germ, Jerusalem artichokes, fermented milk products, cashew nuts…



Zhou L, Xiao X. The role of gut microbiota in the effects of maternal obesity during pregnancy on offspring metabolism. Biosci Rep. 2018 Apr 13;38(2). pii: BSR20171234. doi: 10.1042/BSR20171234