Vaginal Microbiome Exposure and Immune Responses in C-section Infants

The purpose of this research study is to assess at how differences in the microbiome (naturally occurring bacteria) of a baby may protect, or put a baby at risk, for allergic problems. The microbiome refers to the thousands of bacteria and molds that live in and on our bodies. The microbiome plays an important role in our health. Differences in the microbiome can affect our immune system in ways that might make some people more likely to get allergies and asthma.

Early life events and exposures are very important for establishing the human microbiome. The newborn baby's microbiome changes very quickly during the first weeks and months of life. There is information that suggests C-section birth is associated with higher risk of certain diseases, including allergies and asthma. Some researchers think one reason for this is that passing through the mother's vaginal canal during birth exposes the baby to bacteria that promote healthy immune system development, something that C-section babies don't get. Transferring these potentially beneficial vaginal bacteria to C-section babies may help prevent some diseases later.

This is a pilot study of 120 pregnant women and their infants conducted at hospitals in the Mount Sinai Health System in New York, NY. Eighty women will deliver via elective, unlabored C-section, and 40 will undergo spontaneous vaginal delivery. The 80 women undergoing C-section will be randomized in a masked (blinded) 1:1 fashion to have their neonates undergo vaginal seeding or placebo seeding immediately after birth (within 10 minutes) followed by standard care.The infants of the 40 women undergoing spontaneous vaginal delivery will receive usual standard care.

All 120 pregnant women will have biospecimens collected to assess their vaginal, skin, gut, placental, breast milk, and oral microbiome. All infants will have biospecimens collected to assess their gut, skin, nasal, and oral microbiome, as well as blood to assess allergen sensitization and immune markers. Infants will be followed with at-home stool collections and questionnaires weekly for the first 4 weeks and at weeks 8, 26, and 39. An in-person study visit will occur at 13 weeks and 52 weeks, and the primary endpoint will be assessed at 52 weeks. Study enrollment is projected to occur over 24 months.

Eligibility Criteria:
Inclusion Criteria:

* Pregnant woman must be able to understand and provide informed consent;
* Pregnant women with singleton pregnancies with a non-anomalous, appropriately-grown fetus; and
* Atopic disease (asthma, allergic rhinoconjunctivitis, or atopic dermatitis) or food allergy in a first-degree relative of the infant to-be-delivered (for exception, see exclusion criteria\*).

Exclusion Criteria:

For C-Section Mothers:

* In labor with evidence of cervical change prior to the scheduled C-section;
* Rupture of the amniotic sac; or
* Vaginal pH \> 4.5 on the day of delivery.

For Vaginal Delivery Mothers:

- Use of induction agents for cervical ripening (cervical prostaglandin or Foley catheter).

For All Mothers and Their Infants:

* Inability or unwillingness of a participant to give written informed consent or comply with study protocol;
* History of moderate to severe atopic dermatitis within the past year in the mother;
* Express no intention to breastfeed;
* History of diabetes mellitus or gestational diabetes mellitus;
* History of inflammatory bowel disease (IBD) (e.g., Crohn's Disease or ulcerative colitis);
* Evidence of an active sexually transmitted infection (STI) (e.g., primary herpes or genital warts, or trichomonas), yeast infection, or vaginosis on the day of delivery;
* Evidence of prior or current hepatitis B or C infection as demonstrated by the presence of the hepatitis B surface antigen, antibody positivity against the hepatitis B core antigen, or antibody positivity against the hepatitis C virus;

  --Assessment for active hepatitis B and hepatitis C infection will be repeated for this study even if prior testing during the current pregnancy was negative;
* Evidence of Human Immunodeficiency Virus (HIV) infection (e.g., positive HIV serology or detectable viral load);
* Positive Group B Streptococcus (GBS) test results by rectovaginal swab performed within 5 weeks of delivery, a prior infant with invasive GBS disease, or GBS bacteriuria at any point during pregnancy;
* Evidence of N. gonorrhoeae or C. trachomatis infection by testing performed within 5 weeks of delivery;
* History of antibiotic administration during the third trimester of the current pregnancy;
* Mothers with serious chronic conditions during pregnancy;
* Mothers with complicated pregnancies including pre-eclampsia, chorioamnionitis, placenta previa, vasa previa, placental abruption, or active vaginal bleeding;
* Maternal fever on the day of delivery (visit 0);
* Infants with complications during delivery, such that the infant requires more than the standard neonatal resuscitation after delivery;
* Infants delivered prior to 37 weeks of gestation;
* Thick particulate meconium noted upon delivery of the infant;
* Presence of a congenital abnormality in the infant for which study participation is not recommended;
* Current, diagnosed mental illness or current, diagnosed or self-reported drug or alcohol abuse in the mother that, in the opinion of the investigator, would interfere with the participant's ability to comply with study requirements;
* Use of investigational drugs during the third trimester of pregnancy; or
* Past or current medical problems or findings from physical examination or laboratory testing that are not listed above, which, in the opinion of the investigator may:

  * Pose additional risks from participation in the study,
  * Interfere with the participant's ability to comply with study requirements, or
  * May impact the quality or interpretation of the data obtained from the study.