Table 3.

Characteristics of studies evaluating the role of probiotics in perinatal depression.

Author, year	Number of subjects	Intervention period	Probiotics	Result
Browne, 2021	Probiotics (n = 20); placebo (n = 20).	From 26 to 30 weeks of gestation until delivery.	B. bifidum W23, B. lactis W51, B. lactis W52, L. acidophilus W37, L. brevis W63, L. casei W56, L. salivarius W24, L. lactis W19 and L. lactis W58	Probiotics significantly enhanced cognitive reactivity but did not alter anxiety (general, maternal), depression, and pregnancy-related and general daily hassles.
Hulkkonen, 2021	Fish oil (FO) + placebo (n = 87); probiotics + placebo (n = 96); FO + probiotics (n = 93); placebo + placebo (n = 67).	From <18 weeks of gestation until 6-month postpartum.	L. rhamnosus HN001 and B. animalis ssp. lactis 420	Compared with the FO + placebo group, FO + probiotics group had a significantly higher depression score from early to late pregnancy.
Dawe, 2020	Probiotics (n = 115); placebo (n = 115).	From 12-18 weeks of gestation until 36 weeks of gestation	L. rhamnosus GG and B. lactis BB12	Probiotics did not improve maternal anxiety, and functional health and well-being (physical and mental).
Slykerman, 2017	Probiotics (n = 212); placebo (n = 211).	From 14-16 weeks of gestation until 6-month postpartum	L. rhamnosus HN001	Probiotic supplementation was significantly associated with reduced depression and anxiety.