The goal of this clinical trial is to learn whether daily probiotic drops plus vitamin D3 can improve early gut microbiome colonization in healthy infants born by C-section. It will also assess safety and tolerability.
An intervention with probiotics + vitamin D3 will be compared to placebo + vitamin D3 in a double-blind, randomized design, and include an open-label vaginal-born reference group.
Participants will receive study drops daily for 8 weeks and provide stool samples at multiple time points and complete questionnaires/diaries. After the intervention period, there is an optional follow-up period for up to 3 years.