Alterations of the vaginal microbiota in the third trimester of pregnancy and pPROM.

Objective: Preterm premature rupture of membranes (pPROM) is a significant issue in obstetric practice. One of the risk factors for pPROM are vaginal infections in the third trimester of pregnancy.
Patients and Methods: We performed an observational study on 600 pregnant women, analyzing the lactobacillary grade (LBG) and the presence of any pathogenic bacteria and/or Candida at weeks 28 and 32 of pregnancy and recording any pPROM events at delivery. At week 28, in the case of vaginal infection, the patients were treated for 6 days with a topical association of metronidazole+clotrimazole.
Results: At week 28 of pregnancy 54.2% of women had vaginal infection (32.6% bacterial vaginitis, 33.8% candidiasis and 32.4% mixed infection) and/or abnormal vaginal microbiota (67.4% LBG 2a/2b, 32.6% LBG 3). The total number of pPROM was 8 out of 600 (1.3%). The treatment of vaginal infection at week 28 with the topical association of metronidazole+clotrimazole, led to both the eradication of vaginal infections and the restoration of the vaginal microbiota in 72% of the cases, bringing the level of risk of pPROM similar to that of women without vaginal infection at week 28. In addition, the results showed that women with vaginal infections and/or alteration of vaginal microbiota at week 32 of pregnancy had a higher prevalence of pPROM in comparison to the women without vaginal infection at week 32 (p<0.001).
Conclusions: This observational study showed the high prevalence of vaginal infections in the third trimester of pregnancy and its association with pPROM. Furthermore, data suggested the possible benefits of the topical treatment with metronidazole+clotrimazole in pregnancy to eradicate infections, restore the normal microbiota and reduce the risk of pPROM.