A high Nugent score but not a positive culture for genital mycoplasmas is a risk factor for spontaneous preterm birth

Abstract

Objective. This study was performed to evaluate the relationship among the Nugent score for the diagnosis of bacterial vaginosis (BV), the results of vaginal fluid culture for genital mycoplasmas, and the subsequent occurrence of preterm birth.

Methods. The Nugent score and culture for genital mycoplasmas were performed in vaginal fluid obtained from 977 pregnant women (gestational age 13–30 weeks). Vaginal samples were obtained with sterile cotton swabs. The relationship among the Nugent score, vaginal fluid culture results and the occurrence of spontaneous preterm birth was examined.

Results. (1) Of the 977 women, 14% (137) had a Nugent score of ≥8; (2) The prevalence of a positive vaginal culture for genital mycoplasmas was 30% (288); Ureaplasma urealyticum was isolated in 252 (88%), Mycoplasma hominis in 9 (3%), and both in 27 (9%) women; (3) Cases with a Nugent score of ≥8 had a higher rate of a positive vaginal culture for genital mycoplasmas than those with the lower Nugent score (55%vs. 25%; p < 0.001); (4) Women with a Nugent score of ≥8 had a significantly higher rate of spontaneous preterm birth <37 (10%vs. 4%), <34 (5%vs. 2%), and <32 (4%vs. 1%) weeks of gestation than those with the lower Nugent score (at each gestational age, p < 0.05); (5) In contrast, a positive vaginal culture for genital mycoplasmas was not associated with an increased risk for spontaneous preterm birth; (6) Among patients with a positive culture and a Nugent score of ≥8, the frequency of spontaneous preterm delivery (<37 weeks) was 10% (7/72); (7) There was no difference in the incidence of spontaneous preterm delivery according to the results of vaginal culture in patients with a Nugent score of ≥8, as well as in those with a lower Nugent score.

Conclusion. A high Nugent score (≥8) for the detection of BV but not a positive vaginal culture for genital mycoplasmas is a risk factor for spontaneous preterm birth.

Keywords:

• Nugent score
• bacterial vaginosis
• genital mycoplasmas
• Ureaplasma urealyticum
• Mycoplasma hominis
• preterm birth
• prematurity