Study: Low Probiotic Levels & Preterm Birth

Kathy Wheddon Nutritional Therapist DipION

Researchers at Stanford University in California have been looking at possible links between a pregnant woman’s microflora (visit the Probiotics Learning Lab for more information), both in the gastro-intestinal tract and vaginal tract, and the likelihood of her giving birth prematurely.

The study group was made up of 49 pregnant women who all gave regular samples of their microflora throughout their pregnancies, and then again after the birth of their babies. It was the samples taken from the participants' reproductive tracts that proved to be of most interest to the study scientists, who believe that the findings could represent a real breakthrough for their research in to premature birth. Analysis showed that, of the 49 study participants, the 15 women that gave birth prematurely all showed abnormally low levels of bacteria from the ‘probiotic’ Lactobacillus family, whereas those women that maintained their pregnancies to full term showed healthier levels of this particular genus of bacteria.

pregnant woman holding her tummy

Dr David Relman who led the research said ‘These findings may help us screen women and identify and predict those who are more likely to have a baby born too soon’. Premature birth can lead to many different long-term health consequences, some of which can be serious, such as neurological damage and chronic lung diseases, so anything that can be done to prevent this occurrence would be hugely beneficial, with every extra week spent in the womb being advantageous to the future health of the child.

Dr. Relman went on to say that once expectant mothers who are at a high risk of going in to premature labour have been identified using this bacterial analysis method, a targeted treatment plan could be implemented to try to prevent them giving birth prematurely. He stated that a stitch could be placed in the neck of the womb to help prevent premature birth, or that the use of steroids could help to mature the babies lungs more rapidly in readiness for a predicted early birth.

Personally, I agree more with the views of Joe Leigh Simpson, from the U.S based ‘March of Dimes’ charity (a charity dedicated to helping mums have full-term pregnancies and healthy babies), who said that another option (outside of the use of steroids or cervical stitches), would be to use probiotics to rebalance the levels of Lactobacilli in the reproductive tract. He went on to say that ‘having too few friendly bacteria may leave a woman’s womb open to attack by other bacteria and toxins, triggering early birth’.

It would make sense that rebalancing the vaginal microflora (find out more on the Probiotics Learning Lab) with the correct strains of bacteria that naturally colonise this area, would seem a better treatment option than giving steroids which are well known to worsen dysbiosis, or placing a stitch in the womb to physically ‘hold’ the foetus (unnaturally, in my opinion) in place. If a lack of health promoting beneficial flora is a causative factor in premature birth, I would hope that replenishing that vital flora would be the first treatment option to be considered.

Two of the most prominent strains of Lactobacillus found in the vaginal tract are Lactobacillus rhamnosus GR-1®, and Lactobacillus reuteri RC-14 ®. These strains are known to colonise the ‘intimate’ area and to adhere to the endothelial lining of the vaginal tract, however I can only recommend them within the context of maintaining general vaginal health, and do not suppose to make any further links to these study findings.

You can find both of these strains in Optibac For Women.

Optibac For Women

One other interesting point that the Californian study showed was that even amongst the study participants that didn’t go through a premature birth, their levels of friendly Lactobacillus bacteria still dropped dramatically after birth, and in some cases took as long as one year to return to normal. This could explain why having multiple pregnancies close together can be a risk factor for premature birth, as levels of protective Lactobacilli have not returned to normal between each pregnancy.

Perhaps this study will prompt more research in to the link between the vaginal/reproductive tract microflora and premature birth. It could prove to be another promising area of research for probiotics.

Find out more about women's health:

Which probiotics help with thrush?

Can probiotics help with mastitis & breast health?


  1. Macrae, F., (2020). Probiotics Can Cut Chances Of An Early Birth. [online] Mail Online. Available at: <> [Accessed 5 August 2015].​