Table 2 Selection criteria

Inclusion criteria

 Woman ≥ 18 years of age

 Woman less than 20 weeks of gestation

 Woman with singleton pregnancy

 Woman without history of preterm birth or late miscarriage

 Woman with low-risk factor of preterm birth (absence of diabetes, systemic lupus erythematosus, treated hypertension, fetal malformation, cervical conization, or multiple pregnancy)

 Woman affiliated to or beneficiary of a social security system

 Woman who have signed written informed consent

Exclusion criteria

 Woman more than 20 weeks of gestation

 Minor woman or woman deprived of their freedom by a court/administrative decision or woman under legal protection

 Woman who present high-risk factor of preterm birth or late miscarriage

 Woman with extrauterine pregnancy

 Woman with non-evolutive pregnancy

 Woman who have received antibiotic treatment in the week before inclusion

 Woman misunderstanding the written and spoken French language

 Subject participating in another biomedical research protocol