547: Race differentialy impacts variables associated with cervical length in pregnant women

Abstract

A short cervical length is one of the best predictors of preterm birth. It remains unclear if there should be universal or selective screening of pregnant women for cervical length. We evaluated if variables associated with cervix length differed between women according to race. In this prospective study, cervical length was determined by transvaginal ultrasound at a mean of 21 weeks gestation in 414 pregnant women seen in Sao Paulo, Brazil. All women with a short cervix (<25 mm) received progesterone treatment. Composition of their microbiome was determined from vaginal samples by amplification of the V1-V3 region of the gene coding for bacterial 16S ribosomal RNA. Demographic and clinical variables were obtained by chart review. Associations between race and other variables were analyzed by the Kruskal-Wallis and Mann-Whitney tests. The racial distribution of our subjects was 53.4% White (W), 37.2% mixed race (MR) and 9.4% Black (B). On average the three groups did not differ in age, body mass index, gravidity, parity or age at the time of sample collection. Mean cervical length was shorter in B women (28.4 mm) than in W (32.4 mm) or MR (32.8 mm) women (p<0.016). The percent of women with a short cervix was higher in B women (23.1%) than in W (12.2%) or MR (7.8%) women (p<0.026). Mean cervical length significantly increased with maternal age in W (p=0.001) and MR (p=0.045) women but not in B women. Mean cervical length varied with education level only in W women (p=0.039). Lactobacillus crispatus (41-46%) and Lactobacillus iners (31-41%) were the two bacteria that most often were numerically dominant in all three groups. Only in W women was the percent with a short cervix significantly higher when L. iners rather than L. crispatus was dominant (p=0.05). In MR or B women, the percentage of women with a short cervix was similar regardless of whether L. iners or L. crispatus was dominant. Despite progesterone treatment a short cervix in mid-trimester remained associated with delivery at <37 weeks gestation in W and B, but not in MR, women. The factors that influence cervical length in pregnant women vary between different racial groups.