Understanding the microbiome's important role in human health, the investigators wish to
determine how the development of the infant microbiome is impacted by delivery mode,
comparing natural vaginal birth to scheduled C-sections. Investigators will look at the
oral, nasal, skin, vaginal and fecal bacteria of 78 mothers and their infants from birth to
Human microbiota play an important role in the functioning of various organs, as well as the
education of the immune system. Mammals have evolved to be born non-sterile, covered with
the maternal vaginal bacteria that populate the maternal birth canal, as well as to
exclusively breastfeed during early development. Unfortunately, these processes are
substantially altered with modern Western practices, which may have health consequences. In
particular, C-section is associated with an increased risk of immune diseases and allergies.
This study explores the effects of exposing neonates to the vaginal environment at birth,
perinatal antibiotics, and lactation on the acquisition of new microbial genes during the
first year of infant microbiome development.
This study follows 78 babies from healthy mothers (18-40 years old) with uncomplicated
pregnancies. The babies are divided into three groups according to their exposure to the
vaginal environment at birth:
Group 1: (n-26) Babies born via vaginal delivery.
Group 2: (n-26) Babies born via scheduled C-section without exposure to mother's vaginal
bacteria just after birth.
Group 3: (n-26) Babies born via scheduled C-section with exposure to mother's vaginal
microbiota just after birth.
Sampling Time Points:
Subjects may join the study at any point during their pregnancy or soon after delivery. If
possible, samples of the mother will be obtained three times prior to delivery in the third
trimester: at 30, and 4 or fewer days prior to the mother's due date, as well as on the day
of birth prior to delivery. If not possible, samples of mothers and babies can be obtained
from birth onwards. Samples will be collected from both mother and baby at day 1, day 2 or
3, weekly through the first month, and monthly through the first year. During monthly
sampling, a member of the study team will communicate with mothers regularly to assess for
any changes in the infant's diet or health between visits.
Body Sites to be Sampled on Mother and Baby:
At each sampling, a total of 6 samples will be taken from the baby (feces, mouth, nose,
forehead skin, right forearm skin, right hand skin) and 9 will be taken from the mother
(same as for the babies plus right areola, vagina, and breast milk). Sampling will consist
of simple swabbing of the designated body sites, as well as the collection of mother's
Each time samples are collected, information about the subject's diet, medication and
supplement use, sleep, physical activity and overall health will be asked by survey in order
to correlate changes in the life of the subject with changes in his/her microbiota.
C-section with Exposure to the Vaginal Environment Procedure:
Mothers who give birth at NYULMC or Bellevue Hospital and comply with the inclusion and
exclusion criteria for exposure to maternal vaginal contents can choose to expose their
newborn to samples of their vaginal microbiome just after birth. Such mothers will be tested
to confirm that their vaginal pH is acidic (pH ≤ 4), which indicates the dominance of lactic
acid bacteria. Testing of vaginal pH will be performed using pH paper. These procedures
require of the presence of a study member and will only be performed at NYULMC or Bellevue
Samples of vaginal bacteria will be collected prior to C-section. A piece of gauze will be
placed in the birth canal just after antibiotic administration, and removed just before the
caesarian procedure begins. This period will be no longer than 1 hour long. However, any
amount of time the gauze is in the birth canal will be sufficient to proceed with the
swabbing procedure. Once removed from the mother, the gauze will be stored in a sterile
container until birth. Immediately after delivery, a trained study team member will swab the
neonate with the gauze at multiple body sites, starting with the mouth, the face, and then
subsequently the remainder of his/her body. After the swabbing, the 6 samples normally taken
from all newborns will be collected.
Inclusion Criteria for ALL subjects:
- Healthy mothers, 18-40 years old with uncomplicated pregnancies delivering at term
(37 weeks or later)
- Mothers of any ethnic or social background that can speak, read, and understand
English to the extent that they can consent in English OR mothers who do not speak
English yet agree to come to an NYU hospital for all sampling.
Additional inclusion criteria for mothers in the C-section with exposure to the vaginal
environment group (CS+E):
- Scheduled C-section
- Vaginal pH ≤ 4 at the time of birth (as measured via pH paper)
Exclusion Criteria for ALL subjects:
- Mothers with pre-eclampsia or other serious chronic conditions
- Mothers with complicated pregnancies
- Mothers under 18 years of age or over 40 years of age
- Babies with complications during delivery
- Babies delivered prior to 37 weeks of gestation
Additional exclusion criteria for mothers in the C-section with exposure to the vaginal
environment group (CS+E):
- Mothers reported positive to active primary herpes, genital warts, HIV, Group B
Streptococcus, gonorrhea, chlamydia, bacterial vaginosis, yeast infection, or
- Mothers with vaginal pH > 4 at the time of birth (as measured via pH paper).
- Known positive Group B Strep test results by rectal vaginal swab within five weeks of
the scheduled caesarian.