INS and mastitis: Our umbrella review revealed that the most commonly used MBTIsduring pregnancy and lactation were probiotics under the genera Lactobacillus, Bifidobacterium, Streptococcus, Saccharomyces, and Anaerobes. Thus far, probiotics, prebiotics, and synbiotics have been investigated and found to exhibit significant clinical importance in maternal glycaemic control; insulin metabolism; oxidative stress; inflammatory marker reduction; lactational mastitis treatment and prevention; anxiety symptom relief; and inhibition of group B Streptococcus colonisation.