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Gut Microbiome Of Mom & How It Passes To Baby At Birth

Published November 15, 2022

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By Dr. Nicole Avena

There are many factors that affect our gut microbiome- and even more factors that affect both baby and mom’s microbiomes! During pregnancy, the types of food mom eats and the nutrients they hold have a direct effect on baby. From sugar to jogging, all nutritional factors, exercise, weight gain/loss, and prior health of mom will affect how baby’s gut microbiome thrives in the outside world. In fact, 63% of a newborn’s gut microbiome can be traced back to their mother’s gut microbiome. (1)

Let’s start with diet. Everything mom eats affects their microbiome directly, and baby’s microbiome diversity indirectly. The effects of the gut microbiota diversity on overall health continues to be studied, but not many researchers are looking into how the gut-brain axis is related to baby in pregnancy. There has been research showing that after birth, baby builds their immune system and most of their gut microbiome from breastmilk, which passes nutrients and bacteria directly from mom’s diet and lifestyle. Breastmilk contains fat, carbs, and of course- bacteria! This helps baby have an innate immunity to many infections, as well as a strong gut that has been linked to prevention of lifestyle disease in adulthood, like diabetes and heart disease.

Breast milk composition is affected by all the previous lifestyle factors mentioned- diet, exercise, and weight gain or loss. Although we do not know the exact mechanisms, increasing evidence suggests that the maternal environment influences the likelihood of their child developing diseases that are exacerbated in adulthood. (2) This can be related to the gut microbiome and all its power in both mom and baby. The things that effect mom’s health, can also affect babies. You can improve your overall gut microbiome to be prepared for baby, even before their in the picture, by increasing your fiber intake, lowering your added sugar intake, and exercising regularly. Supplementing with clinically proven probiotics for pregnancy and beyond can also help prepare your gut for baby’s arrival.

The gut microbiome of mom is influenced by the presence of processed and unhealthy foods, aerobic exercise, and weight, and improved with diet and exercise… but how exactly is this related to baby? If baby is receiving “bad” bacteria through breastmilk, they are set up to have poor immunity, digestion, and moods. Have no fear if your pregnancy consisted of watching Netflix and eating pretzels, or if you are not breastfeeding! Begin Health Growing Up prebiotics are formulated with human milk oligosaccharides and fiber, it not only supports your child’s digestion now, but also builds their gut microbiome up for the future.

Summary As an expecting mom & nursing mom the food choices you make can indirectly and directly affect your baby’s microbiome. A diverse, nutrient dense diet is key to supporting a healthy microbiome in mom and baby.

1. Maqsood, R., Rodgers, R., Rodriguez, C. et al. Discordant transmission of bacteria and viruses from mothers to babies at birth. Microbiome 7, 156 (2019).

2. Garcia-Mantrana, I., & Collado, M. C. (2016). Obesity and overweight: Impact on maternal and milk microbiome and their role for infant health and Nutrition. Molecular Nutrition & Food Research, 60(8), 1865–1875.


Dr. Nicola Avena

Dr. Nicole Avena

Dr. Avena is a neuroscientist and nutrition expert based in the New York Area.Her focus is on nutrition and brain health throughout the lifespan. She is the author of several books, including What to Feed Your Baby and Toddler.Check her out at