Pregnant womanAs if pregnant women did not have enough to worry, now they have to worry about worrying. Recent research has indicated that stress during pregnancy may alter the vaginal microbiome.

This means that there will not be enough good bacteria for the baby to ingest as it travel down the vaginal canal when it is delivered. This is the baby’s first exposure to good bacteria and is essential for giving the baby a good start in life.

Researchers from the University of Pennsylvania crafted a study with mice by subjecting them to various stresses, such as restraining them during the first trimester (their version of it) and keeping their cages lit at night. 10 other mice were housed under normal circumstances as a control.

They took samples during pregnancy and after birth and found there was a considerable difference in the microbiome between the two groups.

The stressed mice had a wider range of different types of bacteria including more bad bacteria strains and lower levels of lactobacillus. More importantly, they had passed this onto the baby mice. Researchers then looked at the hypothalamus and found that the baby mice had fewer essential nutrients needed to build neurotransmitters in the brain. 

They also found that the expression of 20 genes, necessary for developing of neurons and signalling systems in the brain, was lower in the baby mice of the stressed mothers. The ability to develop these elements is directly related to lactobacillus strains.

This is really quite amazing that stress can play such a role. We live such stressed lives that many of us think it is normal and certainly with  pregnant women, this is likely to be more so, especially since so many women work right up until the time of delivery.

In another study of 56 pregnant women, stress levels were measured with both a questionnaire and a salivary cortisol test. As well, the poop of the babies was measured a number of times between 7 days after birth and 4 months.

Like the mice study, the babies of the stressed mothers had a different ratio of good to bad bacteria and significantly less lactic acid bacteria, critical for developing a competent immune system and optimal brain function. This would also increase the risk of developing allergies.

However being aware of this, women can take precautions. First, they need to be aware that they are stress. Symptoms, such as fatigue, mood swings, impatience, anger, headaches, anxiety and depression are all signs of stress.

Second, developing stress-reducing techniques during pregnancy and breast feeding (or any time for that matter) can lower cortisol levels and help prevent the alteration of the microbiome. Deep breathing during times of stress is one quick solution.

However, changing the lifestyle during this special time would be more helpful. Women need to slow down, and create some quality time for themselves, get plenty of sleep and enjoy their family and friends.

And finally, supporting gut health with prebiotics and probiotics is the key. This can be done with supplements or consuming fermented foods such as kefir, yogurt, sauerkraut, kombucha and kimchi. They can also consumer prebiotics foods such as grains, potatoes, garlic onion, almonds, cabbage, and blueberries.

More research is needed but this is an important piece of information for us all to consider, especially for women who are planning to get pregnant. It would be helpful if women can be educated to develop strategies to for coping with stress. Also, supporting their gut health will also help combat the effects stress can have on the their gut

This may help women have healthier pregnancies and healthier babies.


Maternal Prenatal Stress is Associated with the Infant Intestinal Microbiota. Maartje A.C. Zijlmans, Katri Korpela, J. Marianne Riksen-Walraven, Willem M. de Vos, Carolina de Weerth. Psychoneuroendocrinology, 2015