Biomedical subjects

B M Mercer

Publications and source records attributed to B M Mercer.

At least 37 records · Page 2Linked to original sources

PubMed1999

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.

Adult↗

PubMed1999

Antibiotic use in pregnancy and drug-resistant infant sepsis.

OBJECTIVE: We sought to evaluate the effect of antepartum and intrapartum antibiotic use on antimicrobial-resistant neonatal sepsis. STUDY DESIGN: We analyzed perinatal outcomes for 8474 pregnancies (8593 live births) delivered at 6 hospitals. Data were collected regarding maternal antibiotic use and perinatal course, neonatal cultures, and outcomes. The diagnosis of confirmed neonatal sepsis required at least one positive blood or cerebrospinal fluid culture. Neonatal cultures were evaluated on the basis of the occurrence and timing of maternal antibiotic exposure. RESULTS: There were 96 neonates with confirmed sepsis (11.2/1000 live births). Sepsis was 19.3-fold more common after preterm birth (57 vs 3. 1/1000; P <.001), with 76% of septic infants being delivered preterm. Forty-five percent of pathogens were ampicillin resistant. Ampicillin resistance increased with preterm birth (50% vs 26%; P =. 04), antepartum antibiotics (57% vs 34%; P =.03), intrapartum antibiotics (55% vs 28%; P <.01), and any prenatal antibiotic exposure (52% vs 22%; P =.01). Infection with an organism resistant to at least one maternal antibiotic was more common with intrapartum antibiotic exposure than with antepartum exposure only (57% vs 17%; P =.01). Regarding early-onset sepsis (n = 55), ampicillin resistance was more common with intrapartum antibiotics (50% vs 16%; P <.01), and resistance to at least one maternally administered antibiotic was more frequent with intrapartum exposure (56.7% vs 0%; P <.01). CONCLUSIONS: Maternal antibiotic treatment is associated with neonatal sepsis by organisms resistant to ampicillin and to maternally administered antibiotics.

Ampicillin Resistance↗

PubMed1999

Current obstetrical practice and umbilical cord prolapse.

The aim of this study was to assess the contribution of current obstetrical practice to the occurrence and complications of umbilical cord prolapse. Maternal and neonatal charts of 87 pregnancies complicated by true umbilical cord prolapse during a 5-year period were reviewed. Twin gestation and noncephalic presentations were common features (14 and 41%, respectively). Eighty-nine percent (77) of infants were delivered by cesarean section of which 29% were classical and 88% were primary. The mean gestational age at delivery was 34.0 +/- 6.0 weeks, and the mean birth weight was 2318 +/- 1159 g. Obstetrical intervention preceded 41 (47%) cases (the obstetrical intervention group): amniotomy (9), scalp electrode application (4), intrauterine pressure catheter insertion (6), attempted external cephalic version (7), expectant management of preterm premature rupture of membranes (14), manual rotation of the fetal head (1), and amnioreduction (1). There were 11 perinatal deaths. Thirty-three percent of the infants (32) had a 5-min Apgar score < 7 and 34% had a cord pH < 7.20. Neonatal seizures, intracerebral hemorrhage, necrotizing enterocolitis, hyaline membrane disease, persistent fetal circulation, sepsis, assisted ventilation, and perinatal mortality were comparable in the "obstetrical intervention" and "no-intervention" groups. Most of the neonatal complications occurred in infants < 32 weeks' gestation. We conclude that obstetrical intervention contributes to 47% of umbilical cord prolapse cases; however, it does not increase the associated perinatal morbidity and mortality.

Cesarean Section↗

PubMed1998

Plasma ferritin, premature rupture of membranes, and pregnancy outcome.

OBJECTIVE: The objective of this study was to determine whether plasma ferritin levels predict maternal or neonatal outcomes in women with preterm rupture of membranes at <32 weeks' gestation. METHODS: Plasma from 223 women with premature rupture of membranes at <32 weeks' gestation who had participated in a randomized antibiotic trial were analyzed for ferritin at random assignment and at delivery, and the results were compared with the development of clinical chorioamnionitis, latency until delivery, neonatal sepsis, and a composite adverse neonatal outcome variable. RESULTS: The mean plasma ferritin level rose from 19.2 +/- 29.1 microgram/L on admission to 38.3 +/- 54.3 microgram/L at delivery, with a mean latency of 9.3 +/- 14.6 days. Plasma ferritin levels were significantly higher at both times in mothers whose infants acquired sepsis than in those whose infants did not, especially at delivery (68.5 +/- 96.3 microgram/L vs 32.5 +/- 40.5 microgram/L, P =.01), and neonatal sepsis was 2 to 3 times more common among women with plasma ferritin levels above the median than among those with levels below the median. CONCLUSIONS: Among women with premature rupture of membranes at <32 weeks' gestation, plasma ferritin levels were significantly associated with neonatal sepsis. These data suggest that higher plasma ferritin levels may serve as a marker of infection among women with premature rupture of membranes; however, the clinical utility of plasma ferritin levels in predicting neonatal outcome appears limited.

Adult↗

PubMed1998

A randomized, controlled trial of oral and intramuscular dexamethasone in the prevention of neonatal respiratory distress syndrome.

OBJECTIVE: The study's objective was to compare the efficacies of oral and intramuscular antenatal administration of dexamethasone in reducing neonatal respiratory distress syndrome. STUDY DESIGN: Subjects at high risk for preterm delivery between 24 and 33 weeks' gestation were prospectively randomly assigned to receive either 6 mg intramuscular dexamethasone or 8 mg oral dexamethasone every 12 hours for 4 doses. The regimen was repeated weekly until 34 weeks' gestation if delivery had not yet occurred. A blinded data review was performed. The primary outcome of the trial was respiratory distress syndrome. Data were analyzed in an intent to treat fashion. Comparisons were made with an unpaired t test, chi2 or Fisher exact test, and survival analysis. P <.05 was considered significant. RESULTS: The study was discontinued at 39% enrollment after a blinded review of available outcomes. A total of 170 women with 188 fetuses were randomly assigned. The oral and intramuscular groups had similar mean gestational ages at enrollment (29.9 weeks vs 29.2 weeks) and similar median latencies (9.5 vs 10 days). No difference in the frequency of respiratory distress syndrome was found between the oral and intramuscular groups, (34.3% vs 29.8%). Neonatal sepsis (10.1% vs 1.2%, P =.01) and intraventricular hemorrhage (10.1% vs 2. 4%, P =.04) were significantly higher in the oral group. There were no statistical differences in the frequencies of necrotizing enterocolitis or neonatal death. A subgroup analysis of 112 patients who were delivered at <34 weeks' gestation revealed no statistical difference in respiratory distress syndrome between the groups; however, oral dexamethasone was associated with a significant increase in sepsis (15.9% vs 1.6%, P =.009) and intraventricular hemorrhage (15.9% vs 3.3%, P =.03). CONCLUSION: Oral administration increases neonatal morbidity without demonstrable benefit and should not at this time be used clinically for induction of fetal pulmonary maturation.

Administration, Oral↗

PubMed1998

Comparison between oral and intramuscular dexamethasone in suppressing unconjugated estriol levels during the third trimester.

OBJECTIVES: Unconjugated estriol production depends on fetal adrenal androgen precursors. Fetal exposure to exogenous glucocorticoids results in adrenal suppression with a subsequent decrease in maternal serum unconjugated estriol levels. We compared the efficacy between oral and intramuscular dexamethasone in maternal serum unconjugated estriol suppression at 48 hours after the initial dose among women at risk for preterm delivery. STUDY DESIGN: Twenty-four gravidas at risk for preterm delivery were randomized to receive either 6 mg intramuscular or 8 mg oral dexamethasone every 12 hours for a total of 4 doses. Blood samples (9 mL) were obtained before the initial dexamethasone administration and again after the fourth dose. Serum was separated and frozen at -70 degreesC and subsequently underwent batch analysis. Unconjugated estriol levels were determined by radioimmunoassay with intra-assay and interassay coefficients of variation of 7.9% and 5.5%, respectively. All values are reported as mean +/- SD. The primary statistical analysis was a t test, with P <.05 considered significant. RESULTS: At the time of dexamethasone administration, gestational ages in both groups were similar. Predexamethasone and postdexamethasone unconjugated estriol levels were also similar between the intramuscular and oral groups (5.39 +/- 3.99 vs 1.80 +/- 2.49 ng/mL and 6.05 +/- 3.00 vs 1.61 +/- 1.03 ng/mL, respectively, P >.05). No difference in percent decrease in unconjugated estriol levels was found between the intramuscular (0.67 +/- 0.24) and oral (0.65 +/- 0.39) groups. CONCLUSION: Oral dexamethasone (8 mg) produces similar maternal serum unconjugated estriol suppression compared with intramuscular dexamethasone (6 mg) when evaluated 48 hours after administration.

Administration, Oral↗

PubMed1998

The preterm prediction study: risk factors for indicated preterm births. Maternal-Fetal Medicine Units Network of the National Institute of Child Health and Human Development.

OBJECTIVE: Preterm births occur for many different reasons. Most efforts to identify risk factors for preterm births either ignore cause and consider preterm births as a single entity or examine risk factors for spontaneous preterm births. We performed this study to examine risk factors for indicated preterm births, which constitute more than one quarter of all preterm births. STUDY DESIGN: The study included 2929 women evaluated at 24 weeks' gestation at 10 centers. Information was gathered about demographic factors, socioeconomic status, home and work environments, drug and alcohol use, and medical history. In addition vaginal samples were evaluated for fetal fibronectin and bacterial vaginosis and cervical length was measured by transvaginal ultrasonography. Associations with indicated preterm birth were evaluated by univariate tests and by multivariable analysis with logistic regression. RESULTS: Of the women studied at 24 weeks' gestation 15.3% were delivered of their infants at <37 weeks' gestation. Of these deliveries, 27.7% were indicated preterm births. Risk factors in the final multivariable model were, in order of decreasing odds ratios, mullerian duct abnormality (odds ratio 7.02), proteinuria at <24 weeks' gestation (odds ratio 5.85), history of chronic hypertension (odds ratio 4.06), history of previous indicated preterm birth (odds ratio 2.79), history of lung disease (odds ratio 2.52), previous spontaneous preterm birth (odds ratio 2.45), age >30 years (odds ratio 2.42), black ethnicity (odds ratio 1.56), and working during pregnancy (odds ratio 1.49). Alcohol use in pregnancy was actually associated with a lower risk of indicated preterm birth (odds ratio 0.35). CONCLUSION: The risk factors found in this analysis tend to be different from those associated with spontaneous preterm birth.

Adolescent↗

PubMed1998

The Preterm Prediction Study: recurrence risk of spontaneous preterm birth. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: We sought to estimate the risk of spontaneous preterm birth in parous women by use of obstetric history, fetal fibronectin, and sonographic cervical length. STUDY DESIGN: The probability of spontaneous preterm birth before 35 weeks' gestation was estimated from a logistic regression model with data from 1282 parous women analyzed according to gestational age at the most recent prior delivery (prior preterm birth at 18 to 26 weeks, 27 to 31 weeks, 32 to 36 weeks, and > or = 37 weeks' gestation), fetal fibronectin status (positive = > or = 50 ng/dl), and cervical length by percentile groups (< or = 10th = < or = 25 nm, 10th to 50th = 26 to 35 mm, and > 50th = > 35 mm) measured at 22 to 24 weeks' gestation. Fibronectin and cervical length results were blinded for clinical care. RESULTS: Among fetal fibronectin positive women with a prior preterm birth, the estimated recurrence risk of preterm birth < 35 weeks' gestation was approximately 65% when the cervix was < or = 25 mm, 45% when the cervix was 26 to 35 mm, and 25% when the cervix was > 35 mm at 24 weeks' gestation. For fetal fibronectin negative women with a prior preterm birth, the recurrence risk was 25% when the cervix was < or = 25 mm, 14% when the cervix was 26 to 35 mm, and 7% when the cervix was > 35 mm. The risk of preterm birth was increased among women with a history of preterm delivery but was not influenced by the gestational age at delivery of the most recent preterm birth. CONCLUSION: The recurrence risk of spontaneous preterm birth varies widely according to fetal fibronectin and cervical length. Cervical length and fetal fibronectin results had distinct and significant effects on the recurrence risk of preterm birth. Predicted recurrence risk is increased by twofold to fourfold in women with a positive compared with a negative fetal fibronectin, and it increases as cervical length shortens in both fetal fibronectin-positive and fetal fibronectin-negative women. These data may be useful to care for women with a history of preterm birth and to design studies to prevent recurrent premature delivery.

Adult↗

PubMed1998

Antibiotic therapy for preterm premature rupture of membranes.

Antibiotic treatment of the patient with preterm premature rupture of membranes remote from term significantly prolongs pregnancy and reduces amnionitis without increasing the risk of cesarean delivery. Antibiotic treatment reduces perinatal infectious morbidity including neonatal sepsis, GBS sepsis, and pneumonia. Stratified analysis of the currently available prospective trials also demonstrates a significant reduction in gestational-dependent morbidity, specifically respiratory distress and intraventricular hemorrhage with treatment. This is supported by a reduction in composite infant morbidity and other gestational age-dependent morbidities in the NICHD-MFMU trial. Although the optimal treatment regimen has not been determined, limited duration broad spectrum antibiotic treatment is justified in the setting of conservative management of pPROM remote from term. The patient with pPROM and documented pulmonary maturity near term may benefit more from expeditious delivery than from expectant management with antibiotics.

Anti-Bacterial Agents↗

PubMed1998

Management of preterm premature rupture of the membranes.

In many cases, the management of preterm PROM will be dictated by the presence of advanced labor, intrauterine infection, placental abruption, or nonreassuring fetal testing. These patients should be delivered expeditiously, with group B streptococcus prophylaxis given where possible, and cesarean delivery reserved for routine obstetric indications. The stable patient with PPROM and documented fetal pulmonary maturity is best treated by early induction. Alternatively, the patient with PPROM remote from term can benefit from conservative treatment. Adjunctive antibiotic treatment and serial evaluation of maternal and fetal well-being offer significant potential for the reduction of perinatal morbidity. Although corticosteroid and tocolytic administration remain controversial, there is a theoretical benefit to their administration, particularly if concurrent antibiotic treatment is given to treat subclinical intrauterine infection.

Anti-Bacterial Agents↗

PubMed1998

The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network.

OBJECTIVES: This study was undertaken to determine the relationship between fetal fibronectin, short cervix, bacterial vaginosis, other traditional risk factors, and spontaneous preterm birth. METHODS: From 1992 through 1994, 2929 women were screened at the gestational age 22 to 24 weeks. RESULTS: The odds ratios for spontaneous preterm birth were highest for fetal fibronectin, followed by a short cervix and history of preterm birth. These factors, as well as bacterial vaginosis, were more strongly associated with early than with late spontaneous preterm birth. Bacterial vaginosis was more common--and a stronger predictor of spontaneous preterm birth--in Black women, while body mass index less than 19.8 was a stronger predictor in non-Black women. This analysis suggests a pathway leading from Black race through bacterial vaginosis and fetal fibronectin to spontaneous preterm birth. Prior preterm birth is associated with spontaneous preterm birth through a short cervix. CONCLUSIONS: Fetal fibronectin and a short cervix are stronger predictors of spontaneous preterm birth than traditional risk factors. Bacterial vaginosis was found more often in Black than in non-Black women and accounted for 40% of the attributable risk for spontaneous preterm birth at less than 32 weeks.

Cervix Uteri↗

PubMed1997

Antibiotic therapy for reduction of infant morbidity after preterm premature rupture of the membranes. A randomized controlled trial. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

CONTEXT: Intrauterine infection is thought to be one cause of preterm premature rupture of the membranes (PPROM). Antibiotic therapy has been shown to prolong pregnancy, but the effect on infant morbidity has been inconsistent. OBJECTIVE: To determine if antibiotic treatment during expectant management of PPROM will reduce infant morbidity. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: University hospitals of the National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. PATIENTS: A total of 614 of 804 eligible gravidas with PPROM between 24 weeks' and 0 days' and 32 weeks' and 0 days' gestation who were considered candidates for pregnancy prolongation and had not received corticosteroids for fetal maturation or antibiotic treatment within 1 week of randomization. INTERVENTIONS: Intravenous ampicillin (2-g dose every 6 hours) and erythromycin (250-mg dose every 6 hours) for 48 hours followed by oral amoxicillin (250-mg dose every 8 hours) and erythromycin base (333-mg dose every 8 hours) for 5 days vs a matching placebo regimen. Group B streptococcus (GBS) carriers were identified and treated. Tocolysis and corticosteroids were prohibited after randomization. MAIN OUTCOME MEASURES: The composite primary outcome included pregnancies complicated by at least one of the following: fetal or infant death, respiratory distress, severe intraventricular hemorrhage, stage 2 or 3 necrotizing enterocolitis, or sepsis within 72 hours of birth. These perinatal morbidities were also evaluated individually and pregnancy prolongation was assessed. RESULTS: In the total study population, the primary outcome (44.1 % vs 52.9%; P=.04), respiratory distress (40.5% vs 48.7%; P=.04), and necrotizing enterocolitis (2.3% vs 5.8%; P=.03) were less frequent with antibiotics. In the GBS-negative cohort, the antibiotic group had less frequent primary outcome (44.5% vs 54.5%; P=.03), respiratory distress (40.8% vs 50.6%; P=.03), overall sepsis (8.4% vs 15.6%; P=.01), pneumonia (2.9% vs 7.0%; P=.04), and other morbidities. Among GBS-negative women, significant pregnancy prolongation was seen with antibiotics (P<.001). CONCLUSIONS: We recommend that women with expectantly managed PPROM remote from term receive antibiotics to reduce infant morbidity.

Adult↗

PubMed1997

The Preterm Prediction Study: association of cesarean delivery with increases in maternal weight and body mass index.

OBJECTIVE: Our purpose was to evaluate whether maternal weight and body mass index measured either before or during pregnancy are associated with an increased risk of cesarean delivery. STUDY DESIGN: Maternal weight and height were prospectively collected on 2929 women in the National Institutes of Health Maternal-Fetal Medicine Units Network Preterm Prediction Study. Prepregnancy and 27- to 31-week maternal weight and height were used to calculate the body mass index, and its contribution to the risk of cesarean delivery was determined. Women with prenatally diagnosed congenital anomalies (n = 89) and pregestational diabetes (n = 31) were excluded from analysis. RESULTS: Univariate analysis of risk factors for cesarean delivery in the 2809 eligible women revealed a decreased risk of cesarean delivery with maternal age < 18 years and multiparity; increased risk of cesarean delivery was noted with maternal age > 35 years and a male fetus. Increases in either prepregnancy or 27- to 31-week maternal weight (5-pound units) or body mass index (1.0 kg/m2 units) were significantly associated with an increased odds of cesarean delivery (p = 0.0001). Each unit increase in prepregnancy or 27- to 31-week body mass index resulted in a parallel increase in the odds of cesarean delivery of 7.0% and 7.8%, respectively. Multivariable stepwise logistic regression analysis confirmed the association of male fetus, age, nulliparity, and body mass index as significant variables contributing to cesarean delivery risk. CONCLUSIONS: The risk of cesarean delivery is associated with incremental changes in maternal weight and body mass index before and during pregnancy after adjustment for potential confounding factors. Prepregnancy counseling about optimizing maternal weight and monitoring weight gain during pregnancy to decrease the risk of cesarean delivery are supported by this study.

Adolescent↗

PubMed1997

Obstetric determinants of neonatal survival: influence of willingness to perform cesarean delivery on survival of extremely low-birth-weight infants. National Institute of Child Health and Human Development Network of Maternal-Fetal Medicine Units.

OBJECTIVE: Our purpose was to evaluate the relationship between the approach to obstetric management and survival of extremely low-birth-weight infants. STUDY DESIGN: In this prospective observational study we evaluated 713 singleton births of infants weighing < or = 1000 gm during 1 year at the 11 tertiary perinatal care centers of the National Institutes of Child Health and Human Development network of maternal-fetal medicine units. Major anomalies, extramural delivery, antepartum stillbirth, induced abortion, and gestational age < 21 weeks were excluded. The obstetrician's opinion of viability and willingness to perform cesarean delivery in the event of fetal distress were ascertained from the medical record or interview when documentation was unclear. Grade 3 and 4 intraventricular hemorrhage, grade 3 and 4 retinopathy of prematurity, necrotizing enterocolitis requiring surgery, oxygen dependence at discharge or 120 days, and seizures were considered serious morbidity. Survival without serious morbidity was considered intact survival. Logistic regression was used to evaluate the influence of the approach to obstetric management, adjusted for birth weight, growth, gender, presentation, and ethnicity. RESULTS: Willingness to perform cesarean delivery was associated with increased likelihood of both survival (adjusted odds ratio 3.7, 95% confidence interval 2.3 to 6.0) and intact survival (adjusted odds ratio 1.8, 95% confidence interval 1.0 to 3.3). Willingness to intervene for fetal indications appeared to virtually eliminate intrapartum stillbirth and to reduce neonatal mortality. Below 800 gm or 26 weeks, however, willingness to perform cesarean delivery was linked to an increased chance of survival with serious morbidity. Although obstetricians were willing to intervene for fetal indications in most cases by 24 weeks, willingness to perform cesarean delivery was associated with twice the risk for serious morbidity at that gestational age. CONCLUSIONS: The approach to obstetric management significantly influences the outcome of extremely low-birth-weight infants. Above 800 gm or 26 weeks the obstetrician should usually be willing to perform cesarean delivery for fetal indications. Between 22 and 25 weeks willingness to intervene results in greater likelihood of both intact survival and survival with serious morbidity. In these cases patients and physicians should be aware of the impact of the approach to obstetric management and consider the likelihood of serious morbidity and mortality when formulating plans for delivery.

Cesarean Section↗

PubMed1997

The preterm prediction study: patterns of cervicovaginal fetal fibronectin as predictors of spontaneous preterm delivery. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: Our purpose was to determine how various temporal patterns of fetal fibronectin positivity from 24 to 30 weeks predict subsequent fetal fibronectin test results and spontaneous preterm delivery. STUDY DESIGN: A total of 2929 women had vaginal and cervical fetal fibronectin tests obtained at least once at 24, 26, 28, or 30 weeks, and 1870 women had tests performed at all four gestational ages. Fetal fibronectin values > or = 50 ng/ml were considered positive. Various patterns of positive and negative tests were evaluated for prediction of (1) whether the next fetal fibronectin test would be positive or negative and (2) the percent of women with a spontaneous preterm delivery > or = 4 weeks after the last fetal fibronectin test at < 30, < 32, < 35, and < 37 weeks' gestational age. RESULTS: Women with previous negative test results had only a 3% chance of a subsequent positive test result; however, if the last test result was positive, 29% of the next tests were positive. Of the 1870 women with tests at 24, 26, 28, and 30 weeks, 89% had all negative results, 8.4% had one positive result, 1.8% had two positive results, and 0.8% had three or four positive results. The higher the percent of positive tests at 24 to 26 weeks, at 28 to 30 weeks, or at 24 to 30 weeks, the greater the risk of subsequent spontaneous preterm birth. As an example, the risk of spontaneous preterm birth at < 30 weeks for women with two negative fetal fibronectin test results at 24 and 26 weeks was 0.3% versus 16% for women with two positive results. CONCLUSION: The presence of a positive cervical or vaginal fetal fibronectin test result predicts subsequent positive fetal fibronectin positivity and subsequent spontaneous preterm birth. The greater the percent of positive results, the higher is the risk of spontaneous preterm birth. After a positive test result, two negative results are required before the risk of spontaneous preterm birth returns to baseline.

Cervix Uteri↗

PubMed1997

Preterm labor and preterm premature rupture of the membranes. Diagnosis and management.

Preterm delivery due to preterm labor and pPROM is responsible for most infant morbidity and mortality in the United States. The patient who presents with suspicious symptoms should undergo a thorough evaluation to confirm the diagnosis of either entity and identify a treatable cause. Determination of gestational age, fetal well-being, and the presence of intrauterine infection is a crucial step in subsequent management. Corticosteroid therapy has been demonstrated to be one of the most effective antenatal interventions to reduce infant morbidity and should be administered to patients with preterm labor, if feasible, when fetal pulmonary maturity is absent or undocumented. We recommend a similar protocol regarding gravidas with pPROM remote from term but recognize the need for further study in this area. Acute tocolytic therapy has been demonstrated to offer short-term benefit to enhance corticosteroid effect. However, all of the available tocolytic agents carry significant risks to the mother and fetus. As such, administration of these agents should be given only when the potential benefits outweigh the risks of administration. Evaluation for fetal pulmonary maturity and intrauterine infection, in concert with evaluation of gestational age-dependent risks of prematurity, may be helpful in determining whether tocolysis should be attempted. Adjunctive antibiotic administration has not been shown to reduce maternal or infant morbidity in the face of preterm labor. However, such treatment offers a reduction of chorioamnionitis, prolongation of latency, and a possible reduction of neonatal infectious and gestational age-dependent morbidity in the setting of pPROM remote from term. Finally, current guidelines recommend the administration of intrapartum GBS prophylaxis when preterm birth or prolonged membrane rupture is anticipated if GBS carrier status is unknown or positive. Intrapartum treatment with intravenous penicillin or ampicillin is appropriate.

Adrenal Cortex Hormones↗

PubMed1997

The effect of nifedipine on urinary excretion of calcium in preeclampsia.

Our objective was to determine if maternal urinary calcium excretion is altered during treatment of mild preeclampsia remote from term with the calcium channel blocker nifedipine. One hundred forty-eight women with mild preeclampsia were randomly allocated to treatment with either bed rest alone (n=64) or in combination with nifedipine (n=84) at 26-36 weeks' gestation. All women had 24 hr urine samples collected for creatinine clearance and calcium excretion determination prior to therapy and during treatment. There was no difference in gestational age at the time of urine collection between the two groups. There were no differences in 24-hr creatinine clearance and calcium excretion between the groups prior to therapy. When followed longitudinally, there was a significant reduction in calcium excretion within each group (p=0.0005 control group, p <0.0001 nifedipine group). Further, a significant reduction in calcium excretion was noted following nifedipine therapy (62+/-94 mg Ca/24 hr) compared to the control group (143+/-153 mg Ca/24 hr), p <0.001. Consistent with previous studies, we have shown that progressive hypocalciuria is a feature of preeclampsia. Further, urinary calcium excretion decreased despite nifedipine therapy. Altered urinary calcium excretion may be less reflective of the progression in severity of preeclampsia in patients treated with nifedipine.

Adolescent↗

PubMed1996

The length of the cervix and the risk of spontaneous premature delivery. National Institute of Child Health and Human Development Maternal Fetal Medicine Unit Network.

BACKGROUND: The role of the cervix in the pathogenesis of premature delivery is controversial. In a prospective, multicenter study of pregnant women, we used vaginal ultrasonography to measure the length of the cervix; we also documented the incidence of spontaneous delivery before 35 weeks' gestation. METHODS: At 10 university-affiliated prenatal clinics, we performed vaginal ultrasonography at approximately 24 and 28 weeks of gestation in women with singleton pregnancies. We then assessed the relation between the length of the cervix and the risk of spontaneous preterm delivery. RESULTS: We examined 2915 women at approximately 24 weeks of gestation and 2531 of these women again at approximately 28 weeks. Spontaneous preterm delivery (at less than 35 weeks) occurred in 126 of the women (4.3 percent) examined at 24 weeks. The length of the cervix was normally distributed at 24 and 28 weeks (mean [+/- SD], 35.2 +/- 8.3 mm and 33.7 +/- 8.5 mm, respectively). The relative risk of preterm delivery increased as the length of the cervix decreased. When women with shorter cervixes at 24 weeks were compared with women with values above the 75th percentile, the relative risks of preterm delivery among the women with shorter cervixes were as follows: 1.98 for cervical lengths at or below the 75th percentile (40 mm), 2.35 for lengths at or below the 50th percentile (35 mm), 3.79 for lengths at or below the 25th percentile (30 mm), 6.19 for lengths at or below the 10th percentile (26 mm), 9.49 for lengths at or below the 5th percentile (22 mm), and 13.99 for lengths at or below the 1st percentile (13 mm) (P < 0.001 for values at or below the 50th percentile; P = 0.008 for values at or below the 75th percentile). For the lengths measured at 28 weeks, the corresponding relative risks were 2.80, 3.52, 5.39, 9.57, 13.88, and 24.94 (P < 0.001 for values at or below the 50th percentile; P = 0.003 for values at the 75th percentile). CONCLUSIONS: The risk of spontaneous preterm delivery is increased in women who are found to have a short cervix by vaginal ultrasonography during pregnancy.

Cervix Uteri↗