Probiotics affects vaginal flora in pregnant women, suggesting the possibility of preventing preterm labor. Randomized trial of antibiotics in addition to tocolytic therapy to treat preterm labor. Cervicovaginal microflora and pregnancy outcome: results of a double-blind, placebo-controlled trial of erythromycin treatment.
nan The objective of this study was to assess whether antibiotic therapy plus tocolysis given to women in preterm labor would prolong pregnancy compared with tocolysis alone.
                A randomized, double-blind trial of intravenous mezlocillin and oral erythromycin therapy vs. placebo was used in addition to tocolysis among women in preterm labor < or =34 weeks gestation with intact membranes. Amniocentesis was performed, and chorioamnionic membranes were examined histologically and cultured for microorganisms after delivery.
                Clinical characteristics including gestational age at enrollment, frequency of contractions, cervical Bishop's score, and white blood cell count on admission were similar in the 2 groups. Antibiotic therapy was well tolerated. No significant differences in the interval to delivery, birth weight, and neonatal outcomes were observed between the 2 groups. Women in the antibiotic group had a significantly lower incidence of postpartum infections compared with women in the placebo group. Patients with evidence of upper genital tract infection in either group had a significantly shorter interval to delivery, lower gestational age at delivery, lower mean birth weight, and increased neonatal hospitalization time.
                Lack of an antibiotic effect on the gestational age at delivery may be due to the low prevalence of upper genital tract infection among unselected women in preterm labor, to advanced preterm labor unresponsive to antibiotic therapy, or to an inability of antibiotics given alone to inhibit the cytokine response. Further work is needed to identify markers of upper genital tract infection among women in preterm labor and to evaluate other potential therapeutic interventions. Available information suggests that some instances of preterm birth or premature rupture of membranes are associated with clinically unrecognized infection and inflammation of the lower uterine segment, decidua, and fetal membranes. Various cervicovaginal microorganisms have been recovered from these sites. Many of these microorganisms produce factors that may lead to weakening of the fetal membranes, release of prostaglandins, or both. This study evaluated the presence of various lower genital tract microflora and bacterial conditions in 229 women enrolled in a double-blind, placebo-controlled trial of short-course erythromycin treatment at 26 to 30 weeks' gestation to prevent preterm birth. Demographic, obstetric, and microbiologic parameters were prospectively evaluated. Premature rupture of membranes occurred less frequently (p less than 0.01) among women who received erythromycin (6%) versus placebo (16%). Preterm premature rupture of membranes also occurred less frequently, although not significantly (p = 0.3) in patients who received erythromycin (2%) versus placebo (5%). Erythromycin treatment significantly decreased the occurrence of premature rupture of membranes among women who were initially positive for Chlamydia trachomatis infection. Logistic regression analysis demonstrated that C. trachomatis (p = 0.05; odds ratio, 9), vaginal wash phospholipase C (p = 0.08; odds ratio, 6) and prior preterm birth (p = 0.007; odds ratio 17) were associated with increased risk of preterm birth. Bacterial vaginosis, Mycoplasma hominis, Ureaplasma urealyticum were not significantly associated with increased risk of preterm birth or preterm rupture of membranes. These findings support a role for selected lower genital tract microflora in preterm birth and premature rupture. Large controlled treatment trials of specific infections or conditions associated with preterm birth and premature rupture of membranes are required to confirm the value of antimicrobial treatments in prevention of microbial-associated preterm birth.
Although the use of probiotics appears to treat vaginal infections in pregnancy, there are currently insufficient data from trials to demonstrate any impact on preterm birth and its complications.