This study aims to investigate the changes in the microbiota at different body sites in late pregnancy, in comparison with non-pregnant women, with particular emphasis on archaea, and to identify possible maternal-to-child transfer routes for acquisition of strictly anaerobic microorganisms by analyzing the gut microbiota of new born infants (delivered vaginally or by C-section).

The investigators hypothesize that changes occur in the microbial community during pregnancy in different body sites (vagina, oral etc.) and that the main source of these microorganisms is the mother for vaginally born infants, while C-section born infants acquire most of the anaerobic microbial communities from other sources rather than mother's vaginal and gut microbiota, such as the environment.

Specific Research Objectives will be:

1. To investigate diversity of archaea in the vagina of healthy women in the context with community state types (CSTs), and compare vaginal microbiome in pregnant with non-pregnant healthy women.
2. To identify the presence of archaea in different body sites (oral, gut) or body fluids (amniotic fluid, urine, human milk) within the perinatal microbial communities.
3. To investigate the presence of archaea in the infant's first-days-of-life intestinal community, and to identify the sources of these microorganisms by using source tracking approach.
4. To investigate Human Milk Oligosaccharides (HMOs) in maternal (serum, saliva, urine, breast milk) or intrauterine sources (amniotic fluid) as potential modifiers of the microbial communities in these sites.
5. To analyze associations of maternal/ intrauterine HMOs with infant HMOs and microbiota (meconium and infant stool) in order to investigate vertical transmission of microbiota to the infant.

Inclusion Criteria:

• healthy women
• pregnant women: delivery at term (gestational age 37-42); contractions or rupture of membrane no longer than 12h before admission to hospital

Exclusion Criteria:

• bacterial/ fungal infections
• use of antibiotics/ probiotics in past 3 months
• fetal anomalies
• multiple pregnancies
• diabetes type 1, 2, gestational diabetes
• hypertension, preeclampsia/HELLP
• HIV ( human immunodeficiency virus), HCV (Hepatitis C)
• drug abuse, smoking

Healthy non-pregnant women and women with an ongoing healthy pregnancy. 3 groups will be formed: non-pregnant women (n=30), women delivering vaginally (n=30) and women undergoing C-section (n=30).