A new study has ruled that probiotics do not improve unhealthy vaginal flora when administered vaginally in a daily capsule to patients for 10 days before fertility treatment.


Vaginal flora, vaginal microbiota, or vaginal microbiome are the microorganisms that colonize the vagina.

Probiotics are live microorganisms that are intended to have health benefits when consumed or applied to the body.

Research has shown that pregnancy and live birth rates are higher among women whose vaginal microbiota is dominated by lactobacillus, a genus of lactic-acid-producing bacteria.


Conversely, those with an imbalance or dysbiosis where the lactobacillus concentration is too low may have a lesser chance of an embryo implanting in the uterus.

Pregnancy chances in IVF can be affected by many factors including the type of bacteria which naturally colonise the reproductive tract.

A study published by the European Society of Human Reproduction and Embryology (ESHRE) found “no significant difference” between women using probiotics and those taking a placebo.


The study was carried out at a university fertility clinic between April 2019 and February 2021.

A total of 74 women referred for IVF treatment were recruited, all having an abnormal lactobacillus profile that varied from low to medium quality.

The women were randomly assigned either to receive vaginal probiotic capsules or a placebo.

Samples were taken to determine the effect on the vaginal microbiome following the 10-day course of probiotics, and again in the subsequent menstrual cycle (on cycle day 21 to 25).


Improvement in the vaginal microbiome was taken to mean a shift in receptivity profile from low to medium; low to high; and from medium to high.

Results showed that the vaginal microbiome improved by 40 percent in the placebo group and by 29 percent in those taking the lactobacillus probiotic.

This, the researchers said, did not represent a significant difference.

Similar outcomes were observed in the menstrual cycle after the intervention.


More than a third (34 percent) of all women who took part in the trial showed an improvement between a month to three months later, regardless of whether they took a probiotic or not.

On this basis, the authors suggested that it may be worthwhile to postpone fertility treatment among patients with an “unfavourable” vaginal microbiome until a normal balance is achieved.

Ida Engberg Jepsen, the lead researcher at The Fertility Clinic at Zealand University Hospital, Denmark, said the spontaneous improvement rate observed may provide grounds for a change in approach towards IVF timing.

“The study indicates that administering vaginal lactobacilli probiotics may not improve a suboptimal vaginal microbiome,” she added.


“However, a spontaneous improvement rate over a period of one to three months may provide the basis for an alternative therapeutic approach.

“The strategy would involve postponing fertility treatment until spontaneous improvement occurs, but further research is needed.

“The specific vaginal probiotic tested in this study had no effect on the favourability of the vaginal microbiome before IVF. But probiotics, in general, should not yet be discounted.”

What to do to ensure your vaginal microbiome is healthy

According to New York Times, in the future, there may be research-backed ways to strengthen the vagina’s bacterial defenses, possibly by combining effective probiotics with antibiotics or even by performing vaginal microbiome transplants.

But for now, experts simply don’t know enough about the vaginal microbiome to be able to reliably shift it in the direction of better health.

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