The Ecology of the Vaginal Flora at First Prenatal Visit is Associated with Preterm Delivery and Low Birth Weight

Can assessment of vaginal microbial flora at first prenatal visit predict the outcome of pregnancy?

Pap smears and vaginal cultures were taken from 222 pregnant women at their first prenatal visit. Lactobacillary grades (LBG I-III) on Pap smears were used as a basis for the scoring. Points were added or subtracted according to the morphotypes of the lactobacilli, the presence of abnormal cellular morphology, increased vaginal leukocytosis, visible pathogens or red blood cells, or the finding of cytolysis of epithelial cells. The total score, reflecting the health of the vaginal microflora, was termed "Vaginal Ecology Score (VECO score)" and compared with pregnancy outcome.

A strong correlation was found between the vaginal eco-score (VECO) at first prenatal visit and the birth weight (r2 0.85, p = 0.003), and between the VECO score and the number of days before term delivery took place (r 0.57, p = 0.048). This association persisted after multivariate analysis. After standardization for positive vaginal culture, a VECO score of 4 or more at first visit was associated with lower birth weight, earlier delivery and smaller fetal head circumference, but not with histological chorioamnionitis. Chorioamnionitis, on the other hand, was found more often in the group with positive vaginal cultures at first prenatal visit.

Vaginal micro-ecology can be scored at the first antenatal visit to predict delivery before 40 weeks and lowered birth weight, even in the absence of overt or detectable infectious disease. To assess prematurity below 37 weeks, larger studies are needed. This assessment of the vaginal ecology could also easily be applied on fresh wet mounts or gram stained specimens of vaginal fluid.