There’s no denying newborn babies get a very healthy start in lives when their Moms delivered them naturally and breastfed them for as long as possible. This one-two punch inoculates their tiny gut microbiomes with the bacteria that helps their bodies thrive and fight off diseases naturally.

As we’ve discussed previously, even the best laid plans of parents and their pediatricians change, making a caesarean (C-section) delivery a tough choice but a necessity for some, nonetheless.

Still, Moms have an important say in their young baby’s gut health by choosing to breastfeed, as shown by a pair of recent studies.

C-sections vs. breastfeeding

A Swedish study tracking the development of the infant microbiome by comparing fecal samples from 98 infants reached some of the same problematic conclusions about C-section births as have previous researchers.

For the record, the microbiomes of young babies born vaginally more closely resembled their Moms than those delivered via C-section, according to the study appearing in Cell Host & Microbe.

Although C-section babies receive less microbial help due to their delivery, they still receive some of Mom’s bacteria through direct contact with their skin and mouth.

However, Swedish researchers also found that infant nutrition — making a decision to breastfeed — also drives the development of young microbiomes as they shift to adapt to their new environments.

The big surprise to researchers: How the end of breastfeeding was the key factor in a baby’s shift to an adult-like microbiome, rather than the introduction of solid foods, says lead study author Fredrik Bäckhed of The University of Gothenburg, Sweden.

Bifidobacterium and Lactobacillus, important bacteria young growing babies need, dominated the gut composition of babies who were breastfed at 12 months.

Conversely, the gut microbiomes of babies who were no longer being breastfed were dominated by the Clostridia species prevalent in adults.

How many species of bacteria are found in breast milk?

If Moms needed any more reasons to breastfeed their young babies, Spanish researchers gave them an important one in a 2012 study published by the American Journal of Clinical Nutrition.

DNA sequencing of colostrum (the first liquid secreted by the mammary glands after a woman gives birth) identified more than 700 species of bacteria, far more than expected.

But there are some interesting caveats that may affect the diversity of bacteria a new Mom produces. For one, overweight Moms or women who gained more weight than expected during their pregnancies produced less diverse breast milk.

The kind of delivery also affects the microbial diversity, but not how you might assume, according to the study. As expected, women who delivered their babies naturally had richer breast milk compared to new Moms who had planned a C-section.

However, women who experienced an unplanned C-section delivered breast milk whose composition was bacterially very similar to mothers who gave birth vaginally.

Differences in diversity could be explained by the state of a new Mom’s hormones and physical stress at the time of birth. “The lack of signals of physiological stress, as well as hormonal signals specific to labor, could influence the microbial composition and diversity of breast milk,” according to researchers in a press release.

These results seem to mirror findings in a more recent report about a Mom’s stress levels triggering changes in the ways her baby’s gut health and brain develops.

The good news: Moms can provide their babies a gut healthy boost by giving them a multi-strain probiotic like EndoMune Junior, which contains beneficial strains of Lactobacillus and Bifidobacterium, plus a prebiotic that feeds the good bacteria in their guts.