Lactobacillus Probiotics For Pregnancy Studies (2022)

When mothers start looking for supplementation some of the first things that come up are vitamin d, folic, iodine, and also probiotics.

In this probiotics for pregnancy guide, I am going to be sharing a whole range of scientific studies that look at the effects, probiotics can have on a mother's healthy gut and her baby.

Let's start with a quick overview of what probiotics are then answer the most important question a mother has which is whether probiotics are safe for their baby's health or not.

What Are Probiotics?


Probiotics are live bacteria and yeasts that are good for your gut health and immune system. Billions of bacteria live within our gut flora and perform several important functions that are essential to our metabolism.

Our gut health or digestive health serves as a home for millions of bacteria that play an essential role in the digestion of food and any imbalance in this ecosystem can have severe effects on our overall health.

Good probiotic bacteria that are also known as microbes can also be found in other areas of the human body such as the mouth, urinary tract, vagina, urinary tract, and lungs. Probiotic bacteria may perform the following functions:

  • May help with intestinal health.
  • May help in creating vitamins within the body.
  • Breakdown and absorb some foods.
  • May keep the immune system functioning.
  • May help fight against some bad bacteria.

Probiotics can be found in several types of foods including fermented foods such as pickles and yogurt, kombucha, kefir, buttermilk, cottage cheese, kimchi, and fermented sauerkraut. People also take probiotic supplements that can contain a huge number of different probiotic strains and come in all types of dosages ranging from mild to strong probiotics.

Any imbalance in the number of microbes in our body may lead to severe conditions such as diarrhea, irritable bowel syndrome, inflammatory bowel disease, Crohn's disease, gum disease, sepsis, eczema, and constipation. Probiotic supplements may alleviate the symptoms associated with these diseases and can also lead to healing if taken in the right quantities for a prolonged time but for others probiotics may do nothing.

Why Probiotics Are Important During Pregnancy

During the first 9 months of a mother's pregnancy, the fetus is kept in a sterile environment inside of the womb protected from pathogenic harmful bacteria.

It's only when the baby passes through the birth canal that is it able to be exposed to the mother's gut bacteria and this is when its microbiome is created for the very first time. 

As it passes through this canal the baby will soak up its mother's probiotic bacteria so that's why a mother needs to make sure their gut health is diverse with gram-positive probiotic bacteria.

healthy vaginal microbiome should have billions of friendly lactobacilli bacteria that have protective effects against things like bacterial vaginosis & conditions like candida.

This is vitally important because studies like this one published in the American Journal of Reproductive Immunology showed that the diversity of bacteria in the mother was shown to be directly related to preterm pre-labor rupture of membranes.

Another 2015 study from the Division of Obstetrics and Fetomaternal Medicine, Department of Obstetrics and Gynecology, Medical University showed that mothers with Candida Albicans in early pregnancy were associated with preterm delivery and low birth weight.

This final review further solidifies how important the mother's vaginal health is by claiming that "structural imbalance in the vaginal microbiota" was found in mothers with recurrent miscarriages with an abundance of Atopobium, Prevotella, and Streptococcus bacteria and a lack of Lactobacillus bacteria found

It doesn't stop here though, once the baby is born the mother is then able to pass on more probiotic bacteria through her breastmilk further strengthening the baby's new gut microbiome.

Probiotics For Vaginal Health

Now that we know how crucial a healthy vaginal microbiome can be for the protection of your birth you may want to look into some probiotic strains that have been studied to show benefits for overall vaginal health and to support against conditions like Bacterial Vaginosis and Candida Albicans.

This 2012 randomized controlled trial from the Netherlands looked at the efficacy of Lactobacilli probiotic bacteria vs antibiotics against Urinary Tract Infections and found that in postmenopausal women who had recurring UTIs and found that Lactobacillus Rhamnosus GR-1 / Lactobacillus Reuteri RC-14 could not prevent UTI's but looked promising.

This next trial published in 2018 had a clearer conclusion stating that a "Lactobacilli Mixture" taken along with lactoferrin could be a safe and effective approach for recurring cases of Recurrent Vulvovaginal Candidiasis. This probiotics study was not however carried out on any woman who was pregnant.

Babies Microbiome Through C-Section

Microbiologist, Trevor Lawley claimed that he would be able to tell how the baby was born just by looking at the bacteria in meconium samples from the baby.

It was found that babies born through c-section had lower levels of Bacteroides with it in some cases being completely absent and higher levels of Enterococcus and Klebsiella. Even more, worryingly that 9-months later around 60% of the babies still did not have adequate levels of this bacteria.

This is an issue because it's possible that this could result in higher rates of asthma, eczema, or obesity later on and potentially many more unknown outcomes. One simple remedy to this could be for the mother to take probiotic supplements at the correct times.

Are Probiotics Safe During Pregnancy?

The number one concern from mothers looking into probiotics during pregnancy & whilst breastfeeding is if probiotics and prebiotics will be safe for their baby although this mostly covers Lactobacillus & Bifidobacteria whereas Saccharomyces Boulardii yeast hasn't been studied as much.

This review from Jackie Elias, RPh, Pina Bozzo, and Adrienne Einarson, RN published in the Canadian Family Physician peer-reviewed journal in 2011 did an excellent job at answering that question.

They started by claiming that "during the third trimester of pregnancy" there were no reported cases of adverse events during pregnancy or birth but whilst taking Lactobacillus & Bifidobacteria probiotics.

One reason why the risk was so low was that probiotics are not able to make it to the too "systemic circulation of the fetus" and that probiotic usage during the third trimester had a low chance of affecting organogenesis in the developing embryo.

The conclusion of the analysis on various studies was that were no safety concerns for pregnant or lactating women taking probiotics but they did claim that probiotics were unlikely to be transferred through breast milk although another study I share later on counters this claim.

Another article from the American Pregnancy Association which has 4.15 stars from 40 reviews also stated that probiotics are "probably safe" during pregnancy claiming the risk of contracting bacteremia from Lactobacillus was less than 1 in a million and fungemia less than 1 in 5.6 million from Saccharomyces Boulardii probiotics.

What about in first trimester?

This 2010 randomized controlled trial from the Department of Paediatrics at Turku University Hospital, Finland published in the British Journal of Nutrition

It had 256 women participated in a study that tested probiotics supplementation during the first trimester that included Lactobacillus Rhamnosus GG and Bifidobacterium Lactis Bb12.

It was found that gestational diabetes mellitus was reduced in the probiotics group and more importantly, there were no adverse events reported in the mothers or children. They even went as far as calling the use of probiotics in pregnancy a "safe and cost-effective tool".

Postnatal Depression

new study published in the Scientific Reports peer-reviewed journal in 2021 looked at the efficacy of probiotics as a treatment for prenatal symptoms including anxiety and depression.

The study had 40 women take probiotics once daily from 26 to 30 weeks gestation until delivery or a placebo. The probiotic was 2.5 Billion CFU and contained a good mix of the following bacteria;

Probiotic Strains

  • Bifidobacterium bifidum W23
  • Bifidobacterium lactis W51
  • Bifidobacterium lactis W52
  • Lactobacillus acidophilus W37
  • Lactobacillus brevis W63
  • Lactobacillus casei W56
  • Lactobacillus salivarius W24
  • Lactococcus lactis W19
  • Lactococcus lactis W58.

It was reported that after 8 weeks there was no reported difference between the placebo and probiotic groups meaning that probiotics for postnatal depression may not be a viable treatment at this stage in gestation.

Another 2017 randomized controlled trial from New Zealand looked at the effects of probiotics at 14 -16 weeks gestation and had better results for postpartum symptoms that included maternal anxiety & depression.

423 women were recruited into the trial and consented to take either Lactobacillus Rhamnosus HN001 probiotics or a placebo until 6 months postpartum if breastfeeding. Questionnaires were given at the end of the trial and 380 women completed the trial.

Using modified Edinburgh Postnatal Depression Scale & State-Trait Anxiety Inventory scores the researchers were able to get some data on if the probiotic had any effect. It was found that those who took the L. Rhamnosus daily did have lower Anxiety & Depression scores in the postpartum period.

Eczema Later In Life

This 2012 journal in the International Archives of Allergy claimed that there was some evidence to show that probiotics taken during pregnancy could alter the composition of breast milk.

They also stated that early exposure could be important in the child's future development of allergies like eczema. There weren't any breakthroughs in this journal with the conclusion instead calling for more research into the link between the effects of probiotics on breast milk.

Another journal published 3 years later in 2015 was published in the World Allergy Organization. The results of their probiotics research showed that there wasn't enough evidence to suggest probiotic usage in infants reduces the risk of allergies in childhood.

They did however claim there was enough evidence to show that probiotics could potentially help limit the development of eczema later in life. They suggested pregnant women take probiotics during pregnancy and also during breastfeeding if they were at high risk for developing allergies.

Placental Microbiome

Whether or not the placenta had a microbiome was under contention for some time but this 2016 non peer-reviewed paper from Texas was titled "The Placenta Harbors a Unique Microbiome" which is a bold claim considering how many other scientists would disagree with it.

After collecting placental specimens from 320 women found that there was a placental microbiome containing Firmicutes, Tenericutes, Proteobacteria, Bacteroidetes, and Fusobacteria phyla bacteria. Better quality peer-reviewed studies on probiotics & placentas are still needed to determine if the Placental Microbiome is a real thing or not.

Gestational Diabetes

2017 study conducted by universities in New Zealand that was published in the peer-reviewed British Journal of Nutrition looked at if Lactobacillus rhamnosus HN001 probiotics could reduce gestational diabetes mellitus.

423 women were randomized to either receive 6-billion CFU of Lactobacillus Rhamnosus probiotics or a placebo at 14-16 weeks gestation. Lower rates of diabetes were found in the HN001 group and interestingly no women who previously had GD went on to once again develop GD in the probiotic group.

Another 2010 randomized controlled trial published in the same journal also looked at the roles probiotic supplementation had on pregnancy outcomes & pre/postnatal growth. This trial was carried out by the Department of Paediatrics, Turku University Hospital, Turku, Finland.

256 women during their first trimester of pregnancy agreed to take a Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12 probiotics or placebo but the CFU count or duration of supplementation was not shared.

No differences in prenatal or postnatal growth were noted between groups but one interesting finding was that 36% of the women in the placebo group and 34% in a control group developed gestational diabetes mellitus whereas only 13% did in the probiotics group.

Pregnancy Immunity

With 70- 80% of the immune cells said to be located in the gut microbiome it's the influence probiotics have on intestinal microbiota that could potentially help with fighting against colds and some cases of flu.

It's thought that during pregnancy it's more difficult for a woman's immune system to fight off infections making it a potentially dangerous situation for them and their baby.

The results of this trial which included 1104 participants published in The American Journal of Clinical Nutrition showed that daily consumption of Lactobacillus paracasei CASEI 431® probiotics reduced the duration of respiratory symptoms.

Morning Sickness

According to the Mayoclinic increased vomiting & nausea during pregnancy could be down to a hormone called human chorionic gonadotropinuman since pregnant women experiencing morning sickness often have higher levels of this hormone compared to pregnant women not experiencing hyperemesis gravidarum.

For a long time there weren't any studies on probiotic usage in morning sickness but just last year in 2021, research from UC Davis School of Medicine tested Lactobacillus probiotic bacteria on 32 obstetric women. Amazingly, they discovered that probiotics supplementation reduced the severity of nausea & vomiting while improving quality of life. 

Fecal samples in the women showed that higher levels of gram-negative Akkemansia muciniphila bacteria were found in women with high vomiting scores also the probiotics increased bile salt hydrolase which possibly helped with intestinal mobility and metabolism.

Pregnancy Constipation

A quick browse on Reddit for pregnancy + constipation searches brings up a plethora of results with stories from mothers sharing how they can only have a bowel movement every other day with hemorrhoids forming. It's thought that an increase in the progesterone hormones is the reason for this sudden lack of bowel movements.

This 2015 study in the British Journal of Nutrition, tested Bifidobacterium animalis subsp. lactis, BB-12® on 1248, and analysis was done on 1000 of these participants. It was found that a 1-billion and 10-billion CFU probiotic were both effective on defecation frequency versus placebo.

Studies like this one that Prebiotics were shown to improve functional constipation by producing short-chain fatty acids during the fermentation in the colon. Dark leafy vegetables are excellent to eat during pregnancy for an overall healthy gut and to help feed probiotic bacteria.

Oral Microbiome & Pregnancy

This 2017 paper published in the Journal of Investigative and Clinical Dentistry, claimed that the bacteria in the Oral Microbiome was critical to oral healthcare of not just the mother but also the child during pregnancy.

To test this hypothesis, 132 pregnant women were recruited from the Hiroshima City Asa Citizens Hospital and consented to take part in a study that checked the oral microbiota during different stages of gestation and compared them to non-pregnant women.

At 17 - 28 weeks gestation it was found that compared to non-pregnant women, there were more Candida species along with Porphyromonas gingivalis. It's thought that during pregnancy women are more at risk for periodontal pathogens and that studies into probiotics bacteria like Lactobacillus Salivarius could be looked into.

Closing Thoughts

There is enough evidence to suggest that most Lactobacillus & Bifidobacteria are safe for pregnant mothers provided your purchase is from a reputable brand that performs regular laboratory testing.

It's vital that you discuss any queries with your Doctor before taking a probiotic as they will be the best person to advise on whether or not probiotics are right for you and your baby. I am not a doctor and this guide is not medical advice.

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