Maria Rescigno (Humanitas University, Rozzano, Milan) discusses the role of dysbiosis during pregnancy and the perinatal period, outlining two potential clinical trajectories.

In the first part, she focuses on preeclampsia and placental complications: according to the evidence presented, dysbiosis can shift circulating metabolites—particularly glucose—with downstream effects on the activity of natural killer (NK) cells, which are essential for proper placental vascularization. When these cells are not adequately activated, placental vascular development may be impaired, increasing the risk of adverse outcomes, including miscarriage—an effect observed mainly in preclinical models.

In the second part, attention turns to the newborn’s earliest life stages and the impact of maternal antibiotic use: while often necessary, antibiotics may disrupt the maternal microbiota and reduce the production and transfer of immunoglobulin A (IgA) into breast milk, weakening a key line of protection for the neonate’s still-immature gut. In the absence of IgA, bacteria such as Enterobacteriaceae (for example, Escherichia coli) may cross a fragile intestinal barrier, enter systemic circulation, and contribute to sepsis.

Among possible mitigation strategies, Rescigno mentions adding fermented milk to support IgA development and considering antibiotic options that do not deplete bacterial groups (such as Clostridiaceae) involved in driving IgA responses.