Back in 2015, when I started blogging for The Pulse, I wrote about the benefits of probiotics during pregnancy (see here). I noted that results of studies on probiotics during pregnancy were inconsistent but were leaning towards some positive benefits. These included reducing the risk of diarrhea if you have to take antibiotics, reducing vaginal bacteria, and reducing the risk of eczema for your baby.
Since then, probiotics have continued to grow into a multibillion-dollar business, claiming benefits from weight loss to reducing gum disease. Despite the hype, there has been some serious research on probiotics during pregnancy and breast-feeding. Here are some updates from 2015:
- Antibiotic-associated diarrhea (AAD). Recent research casts some doubts on this benefit. Two large trials published in the prestigious medical journals Lancet and Annals of Internal Medicine found that probiotics were no better than a placebo in preventing AAD. More worrisome, a trial from researchers in Israel, published in 2018, found that probiotics along with antibiotics might delay recovery of the normal bacterial balance in your colon for 5 months or longer. 
- Vaginal infection (bacterial vaginosis). Reducing this condition with probiotics could be important because bacterial vaginosis may increase the risk of preterm birth. Some studies have linked probiotics in pregnancy to a reduced risk of preterm birth. A 2018 review published in BMC Pregnancy & Childbirth, looked at 27 studies on probiotics effects on preterm birth. Probiotics did not increase or decrease preterm birth. It had no effect. 
- Childhood eczema. Reduction of childhood eczema has gotten a boost from a huge review published in the journal PLOS medicine. The review includes over 400 studies. It found that women who took a daily probiotic supplement from 36 weeks of pregnancy through 3-6 month of breastfeeding reduced their baby’s risk of developing childhood eczema by over 20 percent. Eczema is an uncomfortable condition for babies and children that causes dry, cracked, and itchy skin. 
One thing has not changed. There has been no new evidence that probiotics are unsafe during pregnancy. They are still classified as probably safe. According to the American Pregnancy Association, and the National Institute of Health, the risk of getting a bacterial infection from a probiotics is about one in one million. 
Probiotics may not do much for AAD, and probably will not reduce your risk of preterm birth, but probiotics probably will reduce your baby’s risk of eczema. This can be especially important if there is a history of eczema in your family. There are many options for how to take probiotics. You can eat yogurt or take a supplement. Best bet is to talk to your pregnancy care provider for advice.
- Berkeley Wellness, Probiotics Pros and Cons.
- BMC Pregnancy and Childbirth, Pregnancy outcomes in women taking probiotics or prebiotics: a systemic review and meta-analysis.
- Science Daily, Fish oil and probiotic supplements in pregnancy may reduce risk of childhood allergies.
- American Pregnancy Association, Probiotics During Pregnancy.