Objective
The purpose of this study was to determine the perinatal impact of the 2007 American College of Obstetricians and Gynecologists Practice Bulletin on preterm premature membrane rupture.
Study Design
Perinatal outcomes were compared in women who had experienced preterm membrane rupture in the 3 years before the 2007 Practice Bulletin to similar women who experienced preterm premature rupture of membranes in the 3 years after the issue and implementation of the guideline.
Results
After adjustment for gestational age at membrane rupture and steroids, composite severe morbidity (death, respiratory distress syndrome, assisted ventilation for ≥6 hours, sepsis, pneumonia, grade 3 or 4 intraventricular hemorrhage, or necrotizing enterocolitis) was similar by group. Infants in the “after” group experienced less pneumonia and sepsis, similar respiratory morbidity, but more labor inductions and postpartum hemorrhage.
Conclusion
The new guideline significantly decreases severe neonatal infections but is associated with more frequent labor induction and postpartum hemorrhage.
Preterm premature rupture of membranes (PPROM) affects 1-2% of pregnancies but is associated with up to 30-40% of preterm births. In the absence of labor or complications that warrant delivery, expectant care is often practiced until a gestational age is reached beyond which further observation does not significantly reduce prematurity complications but potentially exposes the fetus to infection and inflammation with associated long-term negative consequences. Contemporary PPROM management incorporates glucocorticoids, broad-spectrum antibiotics, and fetal lung maturity assessment. Perinatal outcomes that are associated with this care suggest that expectancy may be abandoned at earlier gestational ages than previously considered.
In April 2007, the American College of Obstetricians and Gynecologists (ACOG) published a revised Practice Bulletin that supported more active PPROM management at earlier gestational ages. However, 2 of 3 recommendations regarding delivery timing were based on limited and inconsistent scientific evidence (level B) and included delivery at 32-33 weeks’ gestation with documented fetal lung maturity or when PPROM occurred at ≥34 weeks’ gestation. An additional recommendation to consider a single course of corticosteroids at 32-33 weeks’ gestation, particularly if pulmonary immaturity was documented, was based primarily on consensus and expert opinion (level C). Moreover, many supporting studies were conducted among predominantly African American women, whose offspring demonstrate accelerated lung maturation compared with white women. Thus, the anticipated benefits of the new practice guideline remained uncertain, particularly in a primarily white population. We therefore conducted a retrospective study that compared short-term maternal and neonatal outcomes before vs after the implementation of the 2007 Practice Bulletin.
Methods
This retrospective, institutional review board–exempt study included all women with a single living nonanomalous fetus who had experienced PPROM at 32 0/7 to 35 6/7 weeks’ gestation from January 1, 2004, to April 1, 2010, and who received care in a single tertiary teaching hospital. A best obstetric estimate of gestational age was determined with the use of menstrual data and first- or second-trimester ultrasonography. Rupture of membranes was diagnosed by sterile speculum examination that confirmed the pooling of amniotic fluid in the vagina, positive nitrazine paper test, and positive ferning test. Those women with PPROM in the 3 years before guideline implementation on April 1, 2007, were compared with those with PPROM in the subsequent 3 years with regard to maternal and newborn characteristics and outcomes. The primary outcome was composite severe neonatal morbidity (any one of the following occurrences: death, respiratory distress syndrome [RDS], assisted ventilation for ≥6 hours, sepsis, pneumonia, grade 3 or 4 intraventricular hemorrhage [IVH], or necrotizing enterocolitis). Secondary outcomes included neonatal intensive care unit (NICU) admission, NICU length of stay, respiratory morbidity (RDS or assisted ventilation for ≥6 hours), and infectious morbidity (culture-proven sepsis or pneumonia).
Women in the “before” group received inpatient care that consisted of a single course of glucocorticoid therapy at 32 0/7 to 33 6/7 weeks’ gestation, a 2-day course of intravenous ampicillin followed by 5 days of oral amoxicillin, and a single 1-g oral dose of azithromycin. Tocolytics were used at physician discretion for up to 48 hours to permit steroid administration. Fetal surveillance included daily biophysical profiles and nonstress tests every 4-8 hours. Delivery ensued after spontaneous labor, documentation of fetal lung maturity by the presence of phosphatidylglycerol in amniotic fluid that was obtained from the vaginal pool or by amniocentesis at 32-36 weeks’ gestation, when 35-36 weeks’ gestation was achieved or sooner for nonreassuring fetal status or clinical chorioamnionitis.
Women in the “after” group received identical care, which varied only with regard to delivery timing. Again, delivery followed spontaneous labor, nonreassuring fetal status, or clinical chorioamnionitis. Alternatively, women in the after group were also delivered at 32 0/7 to 33 6/7 weeks’ gestation if amniotic fluid was obtained from the vaginal pool or by amniocentesis and demonstrated that phosphatidylglycerol was present. If the fluid could not be collected or lung maturity was not demonstrated, delivery was initiated at 34 0/7 weeks’ gestation. Finally, delivery was expedited on admission for PPROM after 34 0/7 weeks’ gestation. As of September 2008, a change in NICU admission policy occurred, whereby all infants who were born after PPROM <36 0/7 weeks’ gestation were admitted to the NICU or intermediate care nursery where they remained until hospital discharge. Previously, 35-week infants were triaged in the delivery room based on respiratory status. Infants who were born at <35 0/7 in both time periods routinely were admitted to the NICU; those infants who were born at ≥36 weeks’ gestation in both time periods were triaged in the delivery room based on respiratory status.
Maternal characteristics, management, interventions, and outcomes were compared by study group. Morbidity included chorioamnionitis (diagnosed by ≥2 of the following occurrences: maternal fever ≥38.0°C, uterine tenderness, malodorous vaginal discharge, maternal leukocytosis, or fetal tachycardia), postpartum hemorrhage (estimated blood loss >500 mL after a vaginal delivery and >1000 mL after a cesarean delivery), postpartum endometritis (maternal temperature of >38.0°C after the first 24 postpartum hours with associated uterine tenderness), and wound infection (periincisional erythema, purulent drainage, or induration in the postoperative period that required antibiotic therapy).
Data were abstracted from the maternal prenatal record, and the maternal and newborn inpatient records. Dichotomous and continuous variables were analyzed with the chi-square and unpaired t -test, respectively. Logistic and linear regression analyses were adjusted for covariates. Significance was considered for a probability value of < .05.
Results
One hundred seventy-one eligible subjects were included: 107 women before and 64 women after guideline implementation. Maternal demographics were similar by study group ( Table 1 ). Women who were cared for under the new guideline were less likely to be treated expectantly, despite having experienced PPROM at an earlier average gestational age. They also more often received steroids to accelerate fetal lung maturity. After adjustment for differences in gestational age at PPROM, this group more often had labor induced and delivered on average 1 week earlier than women with PPROM before the new guideline ( Table 2 ). Despite the increased induction rate, primary and total cesarean delivery rates were similar by group. Maternal morbidity, including clinical and histologic chorioamnionitis, occurred with similar frequency by study group, except for the later cohort that experienced more postpartum hemorrhages. There were no blood transfusions, however, in any subjects ( Table 3 ).
