In American journal of obstetrics & gynecology MFM
BACKGROUND : Vaginal seeding, exposure of neonates to maternal vaginal fluids, has been proposed to improve the microbiota of cesarean-delivered infants, but its impacts on infants' subsequent health outcomes remain unclear.
OBJECTIVES : This study aimed to examine the impacts of vaginal seeding on gut microbiota, growth, and allergy risks in cesarean-delivered infants.
STUDY DESIGN : This randomized controlled trial was conducted at Liuyang Maternal and Child Health Care Hospital in Hunan, China. We estimated that a minimum sample size of 106 was needed by assuming a standardized effect size of 0.6 for the primary outcomes, with a statistical power of 80%, a two-sided type I error of 0.05, and an expected loss to follow-up of 15%. Finally, 120 singleton term pregnant women scheduled for cesarean delivery were enrolled from November 2018 through September 2019. Infant follow-up was completed in September 2021. Participants were randomized in a 1:1 ratio to the vaginal seeding group (n=60; infants were swabbed immediately after birth using gauze preincubated in maternal vagina) or the control group (n=60; routine standard care). The first set of primary outcomes was infant body mass index (BMI) and BMI z-score at 6, 12, 18 and 24 months of age. The other primary outcome was the total allergy risk score at 18 months for 20 common allergens (each scored 0 to 6 points). Characteristics of gut microbiota, overweight/obesity, and allergic diseases and symptoms were included as secondary outcomes. The main analyses were performed according to the modified intention-to-treat principle.
RESULTS : Of 120 infants, 117 were included in the analyses. Infant BMI and BMI z-score did not significantly differ between the two groups at any of the four time points, with the largest difference in point estimates occurring at 6 months: the mean (SD) BMI was 17.5 (1.4) kg/m2 and 17.8 (1.8) kg/m2 in the vaginal seeding and control groups, respectively (mean difference, -0.31 kg/m2 [95% CI, -0.91 to 0.28]; P=.30), and BMI z-score was 0.2 (1.0) and 0.4 (1.1), respectively (mean difference, -0.20 [95% CI, -0.58 to 0.18]; P=.31). The median total allergy risk score was 1.5 (IQR, 0.0-4.0) in the vaginal seeding group and 2.0 (IQR, 1.0-3.0) in the control group (median difference, 0.00 [95% CI, -1.00 to 1.00]; P=.48). For infants from the vaginal seeding group, the relative abundance of genera Lactobacillus and Bacteroides in gut microbiota was slightly yet non-significantly elevated at birth and 6 months, and the risk of overweight/obesity was lower at 6 months (0/57 versus 6/59, relative risk, 0.03 [95% CI, 0.00 to 0.57], P=.03) but not at subsequent time points. Other secondary outcomes did not differ between groups. No adverse events related to the intervention were reported.
CONCLUSIONS : For term infants delivered by cesarean section, vaginal seeding has no significant impacts on the gut microbiota, growth, or allergy risks during the first two years of life.
Liu Yang, Li Hong-Tian, Zhou Shu-Jin, Zhou Hui-Huang, Xiong Ying, Yang Jing, Zhou Yu-Bo, Chen Dun-Jin, Liu Jian-Meng
2022-Nov-02
cesarean delivery, growth, infant, intestinal microbiota, overweight and obesity, total allergy risk score, vaginal microbiota transfer
