Probiotics and pre eclampsia risk in pregnancy.
In the past couple of weeks there has been a lot of buzz around a new Cochrane review that determined an increased risk of pre-eclampsia in pregnancy for women taking probiotics. Many of the news articles I read, and even social media posts I saw from obstetricians, suggested that probiotics were no longer considered safe for pregnant women. This got my antennas twitching, because I know we have many studies proving safety and efficacy of certain probiotic strains in pregnancy. So naturally, I had to dig around and get to the bottom of this for you.
When I finally managed to find the exact study all these people were talking about, I realised it had been significantly misrepresented. It appears a lot of articles were written based on a media blurb on the research foundation site who did the review on June 16, 2022, rather than by journalists who actually read the study themselves. Then everyone who shared information about the study/review were actually just sharing one version of a misrepresented interpretation.
What is pre-eclampsia?
Pre-eclampsia (PE for short) is a hypertensive state in pregnancy, meaning the blood pressure gets dangerously high. It can cause mortality (death) for both the baby and mother, so it’s a serious condition that is only treatable by ending the pregnancy (through birth or termination if too early for birth).
The Cochrane review of probiotics and pre-eclampsia.
Here is the link to the actual study if you would like to access it: Click to read.
The study review was designed to assess the benefit of probiotics for gestational diabetes mellitus (GDM), and found no benefit in taking probiotics in pregnancy for GDM. It did, however, find a link between probiotic use and increased risk of pre-eclampsia (PE). In the study population, the risk of PE was 35 per 1000 in the placebo group, and 65 per 1000 in the probiotic group, showing a statistically significant increase in risk. The review results were collated from 7 studies, 4 of which included overweight or obese participants, and 3 with no restrictions on weight, with the information on PE based on 4 of those studies. In the outcomes of these studies, they also included risks/benefits to the babies, and in the placebo group there were 3 baby deaths per 1000, with only 1 in the probiotic group, based on 3 of the studies that included mortality rates. They determined this to be not statistically significant because of the low numbers, however neonatal mortality is not something a study would expect a high number of hopefully.
The studies in the review used various strains of probiotics. Every strain of probiotic will have a different function within the body, they’re not all just about “gut health”. For example, we know the strain Lactobacillus rhamnosus GG is heavily studied in pregnancy and shows benefit in reducing atopic allergies (eg eczema) by almost 80% in babies. It is a recommended treatment by RACGP, which you can read more about here: Click to read.
When looking only at the 4 studies included in the review that noted the increased PE, all 4 were studies involving overweight or obese women. We are already aware that obesity increases the risk of PE 3-fold, and that up to 10% of obese women are likely to experience PE during pregnancy.(1)
The 4 included studies.
In Calloway et al 2019, 411 women participated in the study, with PE occurring in 4.9% of the placebo group, and 9.2% of the probiotic group. The probiotics used in this study were Lactobacillus rhamnosus and Bifidobacterium animalis spp lactis. Excessive weight gain occurred more in the placebo group than the probiotic group (46% and 32.5%). While these results do show a significant increase in PE in the probiotic group versus placebo group, they are both still within the up to 10% expected PE range for obese women, which makes me question whether it is actually statistically relevant in the obese population.
In Lindsay et al 2014, no negative obstetric outcomes were noted in the version I was able to access online (there may be more information in the paid version that I was unable to read). The same occurred when I read the available information in Oskesene-Gafa et al 2019, with no reported negative increase in maternal or neonatal outcomes. It is possible that these studies included some information in their full reports that I was not able to access without payment, and it is also possible the PE noted in their studies was of a small number.
In Pellonpera et al 2019, the study compared fish oil, probiotics and placebo. From a cohort of 439 women, PE occurred in 1 woman in the fish oil and placebo group, 4 in the probiotics and placebo group, 3 in the fish oil and probiotics group, and 2 in the placebo and placebo group. The probiotics used were Lactobacillus rhamnosus HN001 and Bifidobacterium animals spp lactis 420, which were the same strains used in Calloway et al 2019.
So if we take the above information, it does appear that there is an increased risk of pre-eclampsia in obese pregnant women. Let me stress the word obese though, because all participants in these studies were overweight. There is currently no evidence of an increased risk of pre-eclampsia in the average pregnant woman. Many articles/practitioners are leaving out that crucial bit of information. In the Norwegian Mother & Child Cohort study, which included 70149 women (a significantly larger study group than the ones used in the review), they found that consuming probiotic milk during late pregnancy reduced the risk of pre-eclampsia.
Our general understanding of the microbiome and pre-eclampsia would actually postulate that probiotics should reduce the risk of PE, since gut dysbiosis has been a proven factor in PE risk. This leaves me wondering if treating the dysbiosis prior to pregnancy would then allow safe prescribing of probiotics in obese patients? I’ve always advocated for pre-conception care, which is the basis of our online program ‘Supercharge Your Fertility’. Improving your health prior to pregnancy can help you conceive faster, have a healthier pregnancy, and encourages better outcomes for your child and yourself.
So, what should we take away from this study at the moment? In obese pregnant women, it is not currently recommended that they consume probiotics during pregnancy. However, women of low or average weight should continue to use probiotics in pregnancy as needed. Probiotics and pre eclampsia risk will remain an area of interest in medicine, and we will be sure to keep you updated with any further changes.
I hope you found this article useful. If you did, you may wish to share it with your friends so they can stay informed too.