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OBJECTIVE - The purpose of this study was to describe the occurrence, timing, and outcomes of hospital-based diagnoses of preterm labor.
STUDY DESIGN - Administrative records identified hospital admissions for preterm labor among 2534 women in an ongoing cohort study. Factors that were considered risks for prematurity were examined by logistic regression for an association with any preterm labor diagnosis, a preterm labor diagnosis <33 weeks of gestation, or > or =33 weeks of gestation.
RESULTS - Of 234 women (9%) who experienced hospitalization for preterm labor, 90 women (38%) were delivered in the first episode. Previous preterm birth consistently was associated with a diagnosis of preterm labor. Reporting a sexually transmitted infection (odds ratio, 1.8; 95% CI, 1.1-3.0) or bacterial vaginosis (odds ratio, 2.6; 95% CI, 1.7-4.1) early in pregnancy was associated with hospitalization for preterm labor between 24 and 32 weeks of gestation.
CONCLUSION - The incidence of first-time hospitalization for preterm labor was 9%, with most episodes not resulting in preterm birth. Previous preterm birth was associated therefore with a preterm labor diagnosis.
This study investigated the relation between self-reported vaginal bleeding during pregnancy and preterm birth in a prospective cohort of 2,829 pregnant women enrolled from prenatal clinics between 1995 and 2000 in central North Carolina. The overall association between vaginal bleeding and preterm birth was modest (risk ratio (RR) = 1.3, 95% confidence interval (CI): 1.1, 1.6). Bleeding in the first trimester only was associated with earlier preterm birth (< or =34 weeks' gestation) (RR = 1.6, 95% CI: 1.1, 2.4) and preterm birth due to preterm premature rupture of the membranes (PPROM) (RR = 1.9, 95% CI: 1.1, 3.3). Bleeding in both trimesters was associated with preterm birth due to preterm labor (RR = 3.6, 95% CI: 1.9, 6.8). Bleeding of multiple episodes, on multiple days, and with more total blood loss was associated with an approximate twofold increased risk of earlier preterm birth, PPROM, and preterm labor. In contrast, bleeding in the second trimester only, of a single episode, on a single day, and with less total blood loss was not associated with any category of preterm birth. Vaginal bleeding was not associated with preterm birth among African Amercians (RR = 1.2, 95% CI: 0.9, 1.7). This study indicates that more intense but not less intense bleeding is associated with earlier preterm birth and spontaneous preterm birth presenting as PPROM or preterm labor, and it suggests that bleeding is less predictive of preterm birth among African-American compared with White women.
OBJECTIVES - A population-based assessment of maternal and perinatal morbidity related to respiratory illness during influenza season among pregnant women has not been published. The objectives of this investigation were to describe and quantify the impact of respiratory hospitalization during pregnancy on serious maternal and perinatal morbidity.
STUDY DESIGN - A matched cohort study using an administrative database of pregnant women enrolled in the Tennessee Medicaid population to determine pregnancy outcomes associated with respiratory hospitalizations during influenza season. Pregnant women aged 15 to 44 years with a respiratory hospitalization during influenza seasons 1985-1993 were matched by gestational age and presence of comorbidity with pregnant control subjects without a respiratory hospitalization.
RESULTS - During the eight influenza seasons studied, 293 women with singleton pregnancies had respiratory disease hospitalizations (5.1:1000). Women with asthma had high rates of such hospitalization (59.7:1000). Compared with matched controls, women with respiratory hospitalizations had similar modes of delivery, delivery length of stay, and episodes of preterm labor. The prevalence of prematurity and low birth weight among infants born to such women was likewise similar between the two groups.
CONCLUSION - In this population of pregnant women, those with asthma accounted for half of all respiratory-related hospitalizations during influenza seasons, with 6% of pregnant women with asthma requiring respiratory hospitalization during influenza season, (odds ratio 10.63, 95% CI, 8.18-13.83, compared with women without a medical comorbidity). We detected no significant increase in adverse perinatal outcomes associated with respiratory hospitalizations during influenza season.
OBJECTIVE - Preterm labor is often a prelude to early births and the significant attendant burden of infant morbidity and mortality. Treatment consists of bedrest, hydration, pharmacologic interventions, and combinations of these. We systematically reviewed the effectiveness of tocolytics to stop uterine contractions (first-line therapy) or maintain quiescence (maintenance therapy). Our objective was to evaluate the evidence on the benefits and harms of five classes of tocolytic therapy for treating uterine contractions related to preterm labor--beta-mimetics, calcium channel blockers, magnesium, nonsteroidal anti-inflammatory agents, and ethanol.
STUDY DESIGN - Reports of randomized controlled trials and other study designs in English, French, and German identified from searches of MEDLINE, EMBASE, specialized databases, bibliographies of review articles, unpublished literature, and discussions with investigators in the field were identified. Studies on women with preterm labor between 1966 and February 1999 that met our inclusion criteria were included. Through dual review, we abstracted the following information: study design and masking; definitions of preterm labor and successful tocolysis; patient inclusion/exclusion characteristics; patient demographic characteristics; drug and cointerventions; and numerous birth, maternal, and neonatal outcome measures.
RESULTS - Of the 256 articles evaluated, we abstracted data from 60 first-line and 15 maintenance studies. Of these, 16 first-line and 8 maintenance studies met more stringent requirements for meta-analyses. Studies of first-line tocolysis (grade Fair) reveal a mixed outcome pattern with small improvement in pregnancy prolongation and birth at term relative to placebo. Data were insufficient to show directly a beneficial effect on neonatal morbidity or mortality. Ethanol was less beneficial than, and beta-mimetics were not superior to, other tocolytic options. Maintenance tocolytics (grade Poor) showed no improvements in birth or infant outcomes relative to placebo; these results were confirmed through meta-analysis. In contrast to other tocolytic treatments, maternal harms from beta-mimetics were rated High; all tocolytics were rated as Low risk for short-term neonatal harms.
CONCLUSIONS - Management of uterine contractions with first-line tocolytic therapy can prolong gestation. Among the tocolytics, however, beta-mimetics appear not to be better than other drugs and pose significant potential harms for mothers; ethanol remains an inappropriate therapy. Continued maintenance tocolytic therapy has little or no value.
OBJECTIVE - To examine the association between bacterial vaginosis, vaginal fluid neutrophil defensins, and preterm birth.
METHODS - Vaginal fluid specimens were obtained at 24-29 weeks' gestation from 242 cases with preterm birth and 507 noncases sampled using a case-cohort study design. We tested for bacterial vaginosis by Gram staining and Nugent scores and assayed for neutrophil defensins by enzyme-linked immunosorbent assay. Bacterial vaginosis was studied as a categoric variable (negative, intermediate, and positive), whereas defensins were studied as a continuous, categoric (based on percentiles), and dichotomous measure (presence versus absence). Three gestational age cut points were used to define preterm birth. Modified Cox proportional hazard models were used to evaluate the associations between bacterial vaginosis, defensins, and degree (less than 32, less than 34, and less than 37 weeks) and type (premature rupture of membranes, preterm labor) of preterm birth.
RESULTS - Elevated vaginal fluid neutrophil defensins were not associated with birth before 37 weeks. Compared with women who did not have measurable vaginal fluid defensins, women with higher defensin levels (0-2.8 micro g/mL, 2.8-8.2 micro g/mL, and greater than 8.2 micro g/mL) had a greater risk of delivering before 32 weeks. Hazard ratios adjusted for maternal race and vaginal bleeding during pregnancy and 95% confidence intervals for these defensin levels were 1.7 (0.4, 6.9), 2.4 (0.7, 7.9), and 3.1 (1.0, 9.8), respectively. Bacterial vaginosis status did not influence the association between defensins and preterm birth.
CONCLUSION - Elevated concentrations of vaginal fluid neutrophil defensins at 24-29 weeks' gestation might predict preterm birth before 32 weeks.
OBJECTIVE - The purpose of this study was to evaluate the evidence regarding antibiotics for the treatment of preterm labor.
STUDY DESIGN - Through dual review, we abstracted study design and masking, definitions of preterm labor and pregnancy outcome, patient inclusion/exclusion characteristics, patient demographic characteristics, drug and cointerventions, and numerous birth, maternal, and neonatal outcome measures. We graded the quality of the individual articles and the strength of the evidence for antibiotic benefit.
RESULTS - We abstracted data from 14 randomized trials and 1 observational study. Of these studies, 13 trials met the requirements for a meta-analysis. The meta-analysis demonstrated a mixed outcome pattern with small improvements in pregnancy prolongation, estimated gestational age at birth, and birth weight. Data were insufficient to show a beneficial effect on neonatal morbidity or mortality rates.
CONCLUSION - Treatment of preterm labor with antibiotic therapy can prolong gestation. The benefits of antibiotics are small, and there is considerable uncertainty about the optimal agent, route, dosage, and duration of therapy.
The purpose of this study was to investigate the association between bacterial vaginosis (BV) and cervical dilation and effacement, as measures of impending preterm delivery. The Pregnancy, Infection, and Nutrition Study collected genital tract specimens and documented cervical change from 807 eligible women between 24 and 29 weeks' gestation. BV was assessed with Nugent-scored vaginal smears, and analyzed in relation to cervical measurements. At 24-29 weeks' gestation, <7% of women had a dilated cervix, 31% had a cervix < or =2 cm, and 17.3% had BV. Unadjusted analyses found no associations between BV and cervical measurements. Adjusted logistic regression suggested an association between BV and cervical effacement among women with a sexually transmitted disease (STD) earlier in pregnancy (odds ratio = 1.9, 95% CI 0.8-4.3). Stratified analyses for BV/dilation also suggested interaction with STDs. Overall, BV was not association with cervical dilation or effacement at 24-29 weeks' gestation.
OBJECTIVE - To assess the association between physical violence during the 12 months before delivery and maternal complications and birth outcomes.
METHODS - We used population-based data from 6143 women who delivered live-born infants between 1993 and 1995 in South Carolina. Data on women's physical violence during pregnancy were based on self-reports of "partner-inflicted physical hurt and being involved in a physical fight." Outcome data included maternal antenatal hospitalizations, labor and delivery complications, low birth weights, and preterm births. Odds ratios and 95% confidence intervals were calculated to measure the associations between physical violence, maternal morbidity, and birth outcomes.
RESULTS - The prevalence of physical violence was 11.1%. Among women who experienced physical violence, 54% reported having been involved in physical fights only and 46% had been hurt by husbands or partners. In the latter group, 70% also reported having been involved in fighting. Compared with those not reporting physical violence, women who did were more likely to deliver by cesarean and be hospitalized before delivery for maternal complications such as kidney infection, premature labor, and trauma due to falls or blows to the abdomen.
CONCLUSION - Physical violence during the 12 months before delivery is common and is associated with adverse maternal conditions. The findings support the need for research on how to screen for physical violence early in pregnancy and to prevent its consequences.
OBJECTIVE - To examine the relation between cervical dilatation and length and the risk of spontaneous preterm birth, including its subtypes preterm labor and preterm premature rupture of membranes (PROM).
METHODS - Cervical dimensions assessed by clinical examination were recorded prospectively at 24-29 weeks' gestation in 871 subjects with singleton pregnancies who were followed to delivery. Relative risks (RRs) of preterm birth, preterm labor, and preterm PROM were calculated for clinically distinguishable categories of cervical dilatation and length and for cervical score (length minus dilatation). Regression analysis was used to adjust for confounding. Time to delivery from baseline examination was summarized using survival analysis.
RESULTS - There were 73 spontaneous preterm births (8.3%), 46 preterm labors and 27 cases of preterm PROM. All cervical measurements were associated with increased risks of preterm birth, with increasing abnormality more strongly predictive of risk. The adjusted RR for preterm birth with dilatation of at least 0.5 cm was 2.9 (95% confidence interval [CI] 1.2, 7.3); for length of 1.5 cm or less, the RR was 2.1 (95% CI 1.0, 4.5), and for cervical score less than 2.0, the RR was 2.8 (95% CI 1.4, 5.6). The association with cervical measurements was stronger for preterm PROM than for preterm labor, although precision was limited. These measurements had high specificity (93-99%) and low sensitivity (8-20%) for predicting preterm birth.
CONCLUSION - In asymptomatic women at 24-29 weeks' gestation, greater cervical dilatation and shorter length were associated with increased risk of spontaneous preterm delivery, particularly preterm PROM.