METHODS
A total of 38 healthy pregnant women who were planned to deliver electively at gestational term by caesarean section were sampled in our study at Birmingham Women’s Hospital, UK. Peripheral blood samples were collected prior to the caesarean section and all women were not in labor and had intact membranes. Cord blood samples were taken immediately after delivery. A peripheral blood sample (up to 2 mL) was taken from the neonate at 3 weeks of age. In addition to the blood samples, a neonatal stool sample was collected at birth and at 3 weeks of age from 29 of the recruited neonates. Exclusion criteria included multiple pregnancy, sepsis risk factors (especially maternal fever or chorioamnionitis), GBS positivity in the current pregnancy, genetic conditions of the fetus or the mother, maternal HIV, maternal TB, maternal new-onset viral infection, maternal hypertensive disorder, maternal endocrine condition or diabetes, maternal asthma and maternal autoimmune conditions, as well as maternal medication other than pregnancy supplements. Peripheral blood samples were also collected from 13 healthy, non-pregnant adults (male/female: 6/7).
Informed written consent was obtained from all pregnant women. The study was reviewed and approved by the East Midlands – Nottingham 2 NHS Research Ethics Committee (reference 16/EM/0379).