Morning sickness affects up to 85 percent of pregnant women and is caused by hormonal changes during early pregnancy. Vitamin B6, antihistamines, and some prescription medications are used to treat nausea and vomiting during pregnancy; however, additional treatments that address hormonal imbalances are needed. Findings of a new report show that probiotics reduced nausea and vomiting and improved quality of life in pregnant women.

Levels of hormones such as estrogen and progesterone fluctuate throughout pregnancy altering the composition of the gut microbiota and gastrointestinal function. Gut microbes metabolize food, supplements, and medications and produce compounds such as short-chain fatty acids and bile acids, which are absorbed into the bloodstream and facilitate communication between the microbiota and host. Previous research has demonstrated that probiotics reduce nausea and vomiting; however, research in pregnant women is lacking.

The investigators recruited 32 female participants who were in their first trimester of pregnancy with no high-risk conditions and had reported symptoms of nausea and vomiting. Participants completed two cycles of Nature’s Bounty brand probiotics (containing 10 billion live cultures of Lactobacillus bacteria) consisting of six days of daily probiotics and two days without probiotics. Participants answered daily questionnaires about gastrointestinal symptoms and provided fecal samples in order to sequence bacterial DNA and measure bacterial metabolites.

Probiotic supplementation reduced the severity of nausea and vomiting, but did not significantly alter the concentration of fecal metabolites, except for alpha-tocopherol, a form of vitamin E. Probiotic supplementation also had little effect on the composition of the gut microbiota, except for a progressive reduction in the concentration of Akkermansia bacteria. When measuring copies of important bacterial genes, the researchers found that probiotics increased the expression of a gene required to produce the enzyme bile salt hydrolase more than fivefold. Participants with high levels of fecal alpha-tocopherol, low levels of fecal Akkermansia, and/or high copy numbers of the bile salt hydrolase gene were less likely to report vomiting throughout the study.

The authors interpret these findings to suggest that probiotics enhanced the production of free bile acids in the intestines, facilitating intestinal mobility and metabolism and reducing painful gastrointestinal symptoms.

• Link to full publication.

• Watch this episode in which Dr. Jed Fahey discusses what to consider when choosing a probiotic supplement.