Best probiotic for constipation in pregnancy

How do the options compare?

Strains are compared on the exact dose tested, trial length, the measured outcome, whether the result held in the larger trial, and whether any pregnant participants were included.

• In a triple-blind randomized trial, Bifidobacterium lactis HN019 at 17.2 billion CFU daily for 14 days reduced mean whole gut transit time from 49 plus or minus 30 hours to 21 plus or minus 32 hours (p less than 0.001), while 1.8 billion CFU moved it from 60 to 41 hours (p equals 0.01) and placebo did not change. 1
• A larger 28-day trial of the same strain in 228 adults with functional constipation found no statistically significant difference in colonic transit time between HN019 at 1 billion or 10 billion CFU daily and placebo, with a benefit appearing only in a post-hoc subgroup of 65 participants having three or fewer bowel movements a week. 2
• In a study of Lactobacillus casei strain Shirota at 1 x 10 to the 8th CFU per mL in a 100 mL beverage for 28 days, defecation frequency rose from 4.81 to 7.81 times a week and stool consistency improved from 2.52 to 3.68 on the Bristol scale. 3
• Effects are strain-specific: if a specific kind of Lactobacillus helps with an illness, that does not mean another kind of Lactobacillus, or any Bifidobacterium, would do the same. A 2014 review found some evidence of benefit for constipation, especially for Bifidobacterium lactis. 4
• The baseline steps for constipation are dietary and behavioural: adults should get 22 to 34 grams of fiber a day depending on age and sex, alongside regular physical activity, bowel training at consistent times, and reviewing medicines that slow things down. 5

Which option makes sense?

B. lactis HN019 has the best transit-time numbers and a larger trial that did not replicate them, L. casei Shirota has the best bowel-frequency numbers, and neither has been tested in pregnancy.

Disclosure: Pregnancy Smart makes supplements in this category. The comparison above is written to inform, not to steer readers toward or away from our brand.