Debora F. Kimberlin

Bacterial vaginosis: Association with adverse pregnancy outcome

Bacterial vaginosis is the most common lower genital tract infection encountered among women of reproductive age. This condition can best be considered as a vaginal syndrome associated with an alteration of the normal vaginal flora rather than an infection specific to any one microorganism. Bacterial vaginosis is a clinical condition with a complex microbiology that is characterized by a reduced concentration of a normally abundant Lactobacillus species along with high concentrations of gram-negative and anaerobic bacteria, particularly, Gardnerella vaginalis and Mobiluncus, Bacteroides, Prevotella, and Mycoplasma species. The exact make up of the microorganisms and their relative concentration vary among women who have this condition. Although it was previously regarded as a harmless condition, recent work has linked bacterial vaginosis to numerous upper genital tract complications such as preterm labor and preterm delivery, preterm premature rupture of the membranes, chorioamnionitis, and postpartum endometritis. The findings from recent prospective randomized trials suggest that treatment of bacterial vaginosis in certain women who are at high risk for preterm delivery decreases the rate of preterm birth.

Indicated versus spontaneous preterm delivery: An evaluation of neonatal morbidity among infants weighing ≤1000 grams at birth

OBJECTIVE The aim of the study was to determine whether infants weighing </=1000 g after birth who are born to women who undergo indicated preterm delivery have different neonatal outcomes than do those born as a result of either spontaneous preterm labor or preterm premature rupture of membranes. STUDY DESIGN In a 1-year observational study (1992-1993) the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network collected outcome data for 799 infants whose birth weights were </=1000 g. Only singleton infants with gestational age >20 weeks who were not produced as the result of an induced abortion were included. Our analysis was further limited to infants without major congenital anomalies who survived >2 days, were deemed potentially viable by the obstetrician, and would have undergone a cesarean delivery for fetal indications (N = 411). The primary reason for delivery was categorized as indicated delivery, spontaneous preterm labor, or spontaneous preterm premature rupture of membranes. Selected neonatal outcomes were evaluated among infants born to women in each of these groups. Logistic regression analyses were used to control for the effects of other potentially confounding variables. RESULTS A total of 156 of the 411 infants were born to women who underwent an indicated preterm delivery, whereas 160 were born after spontaneous preterm labor and 95 were delivered after preterm premature rupture of membranes. Univariate analyses revealed significantly lower incidences of grade III or IV intraventricular hemorrhage, grade III or IV retinopathy of prematurity, and seizure activity among infants born in an indicated preterm delivery than among those born after spontaneous preterm labor or preterm premature rupture of membranes. However, infants of women who underwent indicated preterm delivery had a more advanced mean gestational age at birth than did those born after spontaneous preterm labor or preterm premature rupture of membranes (28 +/- 2 weeks, 26 +/- 2 weeks, and 26 +/- 1 weeks, respectively, P <.001). Multiple logistic regression analysis was therefore used to control for the disparity in gestational age. Multivariate analyses did not confirm the apparent improvement in neonatal outcome in the indicated delivery group. CONCLUSION In this population of infants weighing </=1000 g, selected neonatal outcomes did not differ according to birth by indicated preterm delivery, spontaneous preterm labor, or preterm premature rupture of membranes.

THE EFFECT OF MATERNAL MAGNESIUM SULFATE TREATMENT ON NEONATAL MORBIDITY IN 1000-GRAM INFANTS

Data from retrospective observational studies suggest that fetal exposure to magnesium sulfate may correlate with a lower risk of both intraventricular hemorrhage and cerebral palsy in live-born infants. The present study, also retrospective, was done to learn whether extremely low birth weight (1000 gm or less) infants who live at least 2 days after being born to a woman given magnesium for uterine tocolysis had neonatal outcomes differing from those of unexposed infants. Only potentially viable singleton infants with a gestational age of at least 20 weeks were included. None had major congenital anomalies. The final study group of 308 infants, seen in a 12-month period, included 124 exposed in utero to magnesium sulfate and 184 who were not so exposed. Mortality from day 3 to 4 months of life was similar in the two groups. Women given magnesium sulfate for tocolysis were less often black, were more often in active labor at the time of delivery, and received more steroids, but in other respects, the groups were comparable. The infants were similar in birth weight and gestational age at delivery, and there were no significant differences in neonatal morbidity. Multivariate analysis affirmed the lack of any significant association between neonatal disorders and exposure to magnesium sulfate. This included measures of neurological morbidity such as seizure activity and intraventricular bleeding. A prospective randomized trial is needed before concluding that intrapartum magnesium sulfate does not improve the neurological outcome in very premature infants.