Pre-term, premature rupture of membranes (pPROM) occurs when the amniotic sac ruptures before 37 weeks of gestation and prior to the onset of labor. It is a common cause of pre-term birth and is present in about one third of cases in high-resource settings. Maternal and neonatal infection is highly correlated with pPROM. The putative mechanism is that ascending bacteria from the genital tract trigger an inflammatory response in the decidua and fetal membranes. This triggers the release of prostaglandins and other substances that soften the cervix and initiate contractions leading to membrane rupture and preterm delivery. Preterm infants have markedly higher morbidity and mortality rates.
Mechanism of Action
Antibiotics may help in two ways. First, they treat the maternal/ neonatal infection, thereby reducing infection-related morbidity. Second, by stopping the ascending bacteria, antibiotics may prolong pregnancy, allowing the fetus to further mature. The benefit of antibiotics is greatest following pPROM at less than 32 weeks gestation. Ampicillin, amoxicillin, and erythromycin are all commonly used, either in an IV phase followed by an oral phase, or using an oral phase alone.
Current use in High-Resource Settings
Using an IV phase followed by an oral phase, caregivers often prescribe 2g ampicillin and 250mg erythromycin IV every 6 hours for 48 hours, followed by 250mg amoxicillin and 333mg erythromycin every 8 hours for 5 days. Using an oral only program, caregivers often prescribe 250mg orally every 6 hours for 10 days. Systematic review of existing randomized controlled studies does not suggest that oral only regimes are less effective.
Application in Low-Resource Settings
Antibiotics for pPROM are used infrequently in low-resource settings. Even in the absence of other interventions, including antenatal steroids, surfactant, and ventilation, experts estimate that increasing use of antibiotics for pPROM from 0% to 100% could “prevent 4% of neonatal deaths due to complications of prematurity and 8% of those due to infection.” At approximately $0.84 for the full ten day oral course, this may represent an especially cost effective way to save lives.