This project aims at identifying variations in breast milk neutrophils among lactating mothers with gestational diabetes or obesity (objective 1), and to describe how a dietary intervention with Omega-3 fatty acids affects these changes (objective 2). The occurrence of respiratory infections on the progeny will be analysed, as well as its development and the impact on gut microbiota and epigenetic changes (objective 3). The involvement of breast milk on the neonate's microbiota (sub-objective 1) and epigenetic variations (sub-objective 2) will be depicted. In addition, the direct engagement of milk neutrophils in the ability of the progeny to react against lung infections will be studied (sub-objective 3).

To attain these mother milk and blood samples will be obtained from three groups of lactating mothers: control, obesity or gestational diabetes, upon a dietary intervention with Omega-3 fatty acids. Neutrophil populations of maternal blood and milk samples will be studied by flow cytometry and in vitro assays. The microbiome and miRNA content of infant's saliva and tool samples will be characterized by 16s rRNA gene sequencing and PCR. The occurrence of respiratory infections and the development the infants participating in the study will be tracked during the first 2 years of life by telephone surveys.

To study the impact of the presented maternal variables on the progeny upon a respiratory inflammation on a systemic level, mouse models will be employed. The offspring of lactating dams with gestational diabetes or obesity will be subjected to an artificial acute lung infection. The progression of the lung disease will be studied by histology and the neutrophil profile in the organs of the litter by flow cytometry. The response to acute lung injury after fecal transplantation with infant's microbiota intro germ-free mice as well as of wild type pups breastfeed by neutropenic dams will complement the animal studies.

Inclusion Criteria:

• full term pregnancy (>37 weeks)
• mother age 18-50 years
• intention to practice exclusive breastfeeding for at least 3 months

Exclusion Criteria:

• preterm pregnancy (<37 weeks)
• multiple delivery
• delivery complications that compromise the well-being of the newborn
• congenital abnormalities of the baby
• pathologies of the mother such as hypertension, HELLP syndrome, thyroids alterations or nephropathies - drugs or alcohol abuse record
• occurrence of mastitis during the study
• mothers practicing tandem nursing

Only female participants are eligible as the study is focused on lactation