648: The effect of microbiome exposure at birth on pediatric outcomes using a twin cohort discordant for microbiome exposure at birth

Abstract

Microbiome exposure at birth has been associated with long-term pediatric outcomes. However, it is difficult to determine if differences in outcomes are truly due to microbiome exposure at birth or other exposures after birth and in early infancy. Using a twin cohort we sought to determine whether fetal duration of exposure to the vaginal microbiome at birth is associated with pediatric outcomes associated with dysbiosis, namely allergies, asthma, and growth abnormalities. Our hypothesis was that the presenting twin (PT) would have a greater exposure to the vaginal microbiome as compared to the nonpresenting twin (NPT) and therefore should have a lower rate of adverse pediatric outcomes. Pediatric data were collected via survey mailed to parents of twins delivered by a single practice from 2005-2014 and review of their delivery records. We compared pediatric outcomes between the PT and NPT 1) in all twin pairs exposed to labor; 2) in twin pairs exposed to labor who delivered via CS; and 3) in twin pairs exposed to labor who delivered vaginally. We also compared duration of rupture of membranes (ROM) in PTs who did and did not develop asthma or allergies. Chi square and student’s t-testing were used. 667 twin pairs were surveyed, of which 437 mothers responded (65.5% response rate) at a mean age of 5.9 years. After excluding 16 sets of twins for TTTS, monochorionic monoamniotic, fetal anomalies, and intrauterine or neonatal demise, 421 sets of twins remained for analysis, 257 of whom labored. In all three analyses, gender, birthweight, and apgar scores were similar between the PT and NPT, and duration of ROM was significantly longer for the PT. However, pediatric outcomes were similar between the PT and NPT (Table1). When we included only the PT, the mean time of ROM did not differ between children with and without asthma (618 vs. 616 minutes, p=0.997), or with and without allergies (720 vs. 608 minutes, p=0.846). Duration of exposure to the maternal vaginal microbiome in twins does not appear to be associated with select adverse long-term pediatric outcomes traditionally associated with dysbiosis of the neonatal microbiome. This suggests that differences in pediatric outcomes may be more dependant on postnatal exposures, rather than exposure at birth.