Prenatal care and black-white fetal death disparity in the United States: heterogeneity by high-risk conditions

OBJECTIVE

To determine the impact of prenatal care in the United States on the fetal death rate in the presence and absence of obstetric and medical high-risk conditions, and to explore the role of these high risk conditions in contributing to the black-white disparity.

METHODS

This is a population-based, retrospective cohort study using the national perinatal mortality data for 1995-1997 assembled by the National Center for Health Statistics. Fetal death rate (per 1000 births) and adjusted relative risks were derived from multivariable logistic regression models.

RESULTS

Of 10,560,077 singleton births, 29,469 (2.8 per 1000) resulted in fetal death. Fetal death rates were higher for blacks than whites in the presence (4.2 versus 2.4 per 1000) and absence (17.2 versus 2.5 per 1000) of prenatal care. Lack of prenatal care increased the (adjusted) relative risk for fetal death 2.9-fold in blacks and 3.4-fold in whites. Blacks were 3.3 times more likely to have no prenatal care compared with whites. Over 20% of all fetal deaths were associated with growth restriction and placental abruption, both in the presence and absence of prenatal care. Lack of prenatal care was associated with increased fetal death rates for both blacks and whites in the presence and absence of high-risk conditions.

CONCLUSION

In the Unites States, strategies to increase prenatal care participation, especially among blacks, are expected to decrease fetal death rates.

Defining the relationship between obstetricians and maternal-fetal medicine specialists

OBJECTIVE

The purpose of this study was to determine how frequently general obstetricians refer pregnant patients to maternal-fetal medicine specialists in the presence of the clinical indications specified as appropriate for referral or consultation by the 1996 statement of the Society of Perinatal Obstetricians.

STUDY DESIGN

A questionnaire was mailed to 400 randomly selected general obstetricians across the United States. The obstetricians were asked how often they refer their high-risk pregnant patients to maternal-fetal medicine specialists in the presence of (1) a need for diagnostic or therapeutic procedures, (2) medical/surgical disorders, (3) healthy gravid women with high-risk fetuses, and (4) conditions that necessitate admission for reasons other than delivery. Response categories for each individual procedure/high-risk condition included "always," "frequently," "infrequently," "never," and "not applicable."

RESULTS

Overall, 55% of the responses indicated referral (always or frequently) to maternal-fetal medicine specialists for procedures or in the presence of high-risk conditions. More than 75% of the obstetricians always or frequently refer to maternal-fetal medicine specialists for most diagnostic/therapeutic procedures and for the following high-risk conditions: acute fatty liver, portal hypertension, pulmonary hypertension, transplantations, fetal hydrops, fetal anomaly/cytogenetic abnormality, fetal supraventricular tachycardia or congenital heart block, isoimmunization, and twin-to-twin transfusion syndrome.

CONCLUSION

Most of the conditions for which >75% of the obstetricians refer to maternal-fetal medicine are rarely seen in practice. Comprehensive ultrasound examination is the only commonly encountered clinical situation that >75% of the general obstetricians refer to maternal-fetal medicine specialists.

Rates of preterm delivery among Black women and White women in the United States over two decades: an age-period-cohort analysis

The authors assessed the influence of age, period, and cohort effects on rates of preterm delivery in the United States. Rates of preterm delivery for singleton births (<37 weeks) in seven age groups (15-19, 20-24,., 45-49 years), five periods (1975, 1980, 1985, 1990, 1995), and 11 maternal birth cohorts (1926-1930, 1931-1935,., 1976-1980) were examined. Over the 20-year study interval, preterm delivery increased by 3.6% among Blacks (from 15.5% in 1975 to 16.0% in 1995) and by 22.3% among Whites (from 6.9% to 8.4%). Among Black primigravid women, rates of preterm delivery increased from 1975 to 1990 and began to decline thereafter; among Whites, the rates increased between 1975 and 1995. In Blacks, women aged 25-29 years had the lowest rates for the first and second births, and women aged 30-34 years had the lowest rate for subsequent births. In Whites, the age groups with the lowest preterm delivery rates were 20-24 years for first births and 25-29 years for subsequent births. Cohort-specific rates of preterm delivery remained fairly constant across age strata and periods for Whites, but a small trend was apparent for Blacks aged 30-44 years. The consistency of the observed age effects across periods and cohorts suggests that the age effect is partly due to biologic factors. The presence of period effects might be linked to the increased survival of premature infants or to increased viability among births occurring at lower lengths of gestation.

Appropriateness of antibiotic use in the postpartum period

OBJECTIVE

To determine the appropriateness of current postpartum antibiotic use in clinical practice.

METHODS

Medical records were reviewed for all patients delivering in a 3-month period who received postpartum antibiotics during the delivery hospitalization. Subjects were excluded if they received a single postpartum antibiotic dose as part of a mitral valve prolapse prophylaxis protocol, or if they received no more than one postpartum antibiotic dose for surgical prophylaxis. Characteristics of postpartum antibiotic use were abstracted.

RESULTS

Two hundred and eleven of 1537 (14%) delivering patients met the inclusion criteria. Seventy-four (35%) delivered vaginally and 137 (65%) delivered by Cesarean section. Postpartum fevers were found in 40 (54%) of vaginal delivery cases and 80 (58%) of women delivering by Cesarean section who received postpartum antibiotics (p = 0.54). For vaginal deliveries there were no differences in the duration of antibiotic use or number of antibiotic doses based on fever status. For Cesarean deliveries, a fever was associated with more antibiotic doses and a longer duration of antibiotic use. Physician justification for antibiotic use was documented in only 116 cases (55%).

CONCLUSIONS

The high proportion of women receiving postpartum antibiotics having no evidence for infection or documented indication for therapy suggests that antibiotics may not be appropriately used in the postpartum period.

Revisiting sonographic abdominal circumference measurements: a comparison of outer centiles with established nomograms

OBJECTIVE

To construct an institution-specific nomogram of fetal abdominal circumference measurements and determine whether previously published nomograms correctly categorize our population's outer centiles.

DESIGN

Using cross-sectional data from a database of sonographic circumference measurements, a nomogram for abdominal circumference measurements was created by modeling the mean and standard deviation separately. The adequacy of the nomogram was confirmed by assessing the normal distribution of data, verifying goodness-of-fit, and checking residuals. Outer centiles were compared with those from other published nomograms.

RESULTS

The new nomogram for fetal abdominal circumference measurements from 10 070 fetuses provided sufficient data to derive values for the 5th, 10th, 50th, 90th and 95th centiles based on gestational age. Comparisons with other published nomograms indicated that the false-negative rates for classifying our population as < 10th centile or > 90th centile ranged from 11.3% to 90.5% and from 0 to 66.4%, respectively.

CONCLUSION

Institution-specific nomograms of fetal abdominal circumference measurements are important to avoid incorrect categorization of outer centiles.

Relationship among placenta previa, fetal growth restriction, and preterm delivery: a population-based study

OBJECTIVE

To examine the independent contributions of prematurity and fetal growth restriction to low birth weight among women with placenta previa.

METHODS

A population-based, retrospective cohort study of singleton live births in New Jersey (1989-93) was performed. Mother-infant pairs (n = 544,734) were identified from linked birth certificate and maternal and infant hospital discharge summary data. Women diagnosed with previa were included only if they were delivered by cesarean. Fetal growth, defined as gestational age-specific observed-to-expected mean birth weight, and preterm delivery (before 37 completed weeks) were examined in relation to previa. Severe and moderate categories of fetal smallness and large for gestational age were defined as observed-to-expected birth weight ratios below 0.75, 0.75-0.85, and over 1.15, respectively, all of which were compared with appropriately grown infants (observed-to-expected birth weight ratio 0.86-1.15).

RESULTS

Placenta previa was recorded in 5.0 per 1000 pregnancies (n = 2744). After controlling for maternal age, education, parity, smoking, alcohol and illicit drug use, adequacy of prenatal care, maternal race, as well as obstetric complications, previa was associated with severe (odds ratio [OR] 1.37, 95% confidence interval [CI] 1.25, 1.50) and moderate fetal smallness (OR 1.24, 95% CI 1.17, 1.32) births. Preterm delivery was also more common among women with previa. Adjusted OR of delivery between 20-23 weeks was 1.81 (95% CI 1.24, 2.63), and 2.90 (95% CI 2.46, 3.42) for delivery between 24-27 weeks. OR for delivery by each week between 28 and 36 weeks ranged between 2.7 and 4.0. Approximately 12% of preterm delivery and 3.7% of growth restriction were attributable to placenta previa.

CONCLUSION

The association between low birth weight and placenta previa is chiefly due to preterm delivery and to a lesser extent with fetal growth restriction. The risk of fetal smallness is increased slightly among women with previa, but this association may be of little clinical significance.

Association of maternal fever during labor with neonatal and infant morbidity and mortality

OBJECTIVE

To examine the association of intrapartum fever with infant morbidity and early neonatal (0-6 days) and infant (0-364 days) death.

METHODS

We carried out a retrospective cohort analysis among singleton live births in the United States for the period 1995-1997 using the National Center for Health Statistics linked birth-infant death cohort data.

RESULTS

Among the 11,246,042 singleton live births during the study period, intrapartum fever (at least 38C) was recorded in 1.6%. Intrapartum fever was associated with early neonatal (adjusted odds ratio [OR], 95% confidence interval [CI] for preterm and term infants respectively: 1.32; 1.11, 1.56 and 1.67; 1.14, 2.46) and infant (OR, 95% CI for preterm and term, respectively: 1.31; 1.14, 1.51 and 1.27; 1.01, 1.59) death among nulliparous mothers. Among preterm infants of parous mothers, intrapartum fever was associated with early neonatal (OR 1.29, 95% CI 1.01, 1.64) death. In the combined analyses (infants of nulliparous and parous mothers), intrapartum fever was a strong predictor of infection-related death. These associations were stronger among term (OR 3.16, 95% CI 1.56, 6.40 for early neonatal; OR 1.75, 95% CI 1.20, 2.57 for infant death) than preterm infants (OR 1.52, 95% CI 1.15, 2.00 for early neonatal; OR 1.29, 95% CI 1.05, 1.57 for infant death). Intrapartum fever was also a risk factor for meconium aspiration syndrome, hyaline membrane disease, neonatal seizures, and assisted ventilation.

CONCLUSION

Intrapartum fever is an important predictor of neonatal morbidity and infection-related mortality.

Ultrasonography of the fetal thyroid: nomograms based on biparietal diameter and gestational age

OBJECTIVE

To describe gestational age-dependent and -independent nomograms for fetal thyroid size.

METHODS

Two hundred fetuses were evaluated between 16 and 37 weeks' gestation in this cross-sectional study.

RESULTS

Nomograms of fetal thyroid size were created by using the 5th, 10th, 50th, 90th, and 95th percentiles based on biparietal diameter and gestational age. A second-order polynomial fit for biparietal diameter and a linear fit for gestational age best described thyroid circumference measurements. Variations in thyroid circumference measurements increased with both larger biparietal diameter and advancing gestational age. There was no intraobserver or interobserver variability in thyroid circumference measurements (P > .20).

CONCLUSIONS

Both biparietal diameter and gestational age serve as good predictors of fetal thyroid circumference. When the biparietal diameter is difficult to measure, gestational age can be used to assess thyroid size.

New Jersey's electronic birth certificate program: variations in data sources

OBJECTIVES

This study sought to determine primary sources of data for electronic birth certificates.

METHODS

A survey was administered from 1997 through 1998 to maternity facilities in New Jersey requesting information about what primary information sources were used for 53 electronic birth certificate variables. Potential information sources included the facilities' maternal and infant medical records, the prenatal record, and a parent-completed birth certificate worksheet.

RESULTS

Among the 66 maternity facilities responding, there was significant variation in the choice of primary data sources for the electronic birth certificate variables examined.

CONCLUSIONS

The variability of primary sources for electronic birth certificate data acquisition represents a potential cause of systematic error in reported vital statistics information.

Placental abruption among singleton and twin births in the United States: risk factor profiles

The authors performed a population-based epidemiologic study to evaluate and contrast risk factor profiles for placental abruption among singleton and twin gestations. Data were derived from linked US birth/infant death files for 1995 and 1996, comprising 7,465,858 singleton births and 193,266 twin births. The authors also evaluated effect modification between smoking and hypertension and the effect of a dose-response relation with number of cigarettes smoked daily on abruption risk. Abruption was recorded in 5.9 per 1,000 singleton births and 12.2 per 1,000 twin births. Risk factors for abruption among singleton and twin births, respectively, included preterm premature rupture of membranes (adjusted relative risks (RRs) = 4.89 and 2.01), eclampsia (RRs = 3.58 and 1.67), anemia (RRs = 2.23 and 2.33), hydramnios (RRs = 2.04 and 1.66), renal disorders (RRs = 1.54 and 2.56), and intrapartum fever (>100 degrees F) (RRs = 1.17 and 1.69). Chronic hypertension (RR = 2.38) and pregnancy-induced hypertension (RR = 2.34) were risk factors for abruption in singleton births but not in twin births. Number of cigarettes smoked daily demonstrated a dose-response trend for abruption risk in singletons and twins. Abruption was more likely to occur among smokers with chronic hypertension (RRs = 4.66 and 3.15) and eclampsia (RRs = 6.28 and 5.08). The authors conclude that abruption is twice as likely to occur in twins as in singletons with differing risk factor profiles. This suggests that abruption in twins may result from different pathophysiologic processes.

Do maternal-fetal medicine practice characteristics influence high-risk referral decisions by general obstetrician-gynecologists?

OBJECTIVE

To determine whether the decision of the general obstetrician-gynecologist to refer high-risk obstetric patients depends on the type of practice of the maternal-fetal medicine (MFM) specialist.

METHODS

A questionnaire was mailed to 935 general obstetrician-gynecologists who were asked whether the MFM specialist's practice characteristics would influence their decision to refer their high-risk obstetric patients. Potential MFM practice components presented in the survey included: MFM, high-risk obstetrics, low-risk obstetrics or general obstetrics and gynecology.

RESULTS

A total of 140 (15%) general obstetrician-gynecologists responded, 110 of whom were practicing obstetrics. Of the practicing responders, 77% stated that they were more likely to refer their high-risk obstetric patients if the MFM specialist practiced only MFM and high-risk obstetrics; 69% were less likely to refer their patients when the MFM specialist, in addition to MFM, practiced general obstetrics; and 75% were less likely to refer their patients when the MFM specialist also practiced general obstetrics and gynecology. The MFM practice setting (university vs. community hospital vs. private practice), as well as the geographic location and years of practice of the respondents, did not influence the general obstetrician-gynecologists' decision to refer their high-risk obstetric patients.

CONCLUSION

General obstetrician-gynecologists are more likely to refer high-risk obstetric patients if the MFM specialist practiced only MFM and high-risk obstetrics.

Effect of labor on infant morbidity and mortality with preterm premature rupture of membranes: United States population-based study

OBJECTIVE

To evaluate whether labor, in the setting of premature rupture of membranes (PROM), affects infant morbidity and mortality rates.

METHODS

We derived data for this population-based cohort study from the United States national linked birth infant death data sets, comprised of singleton live births delivered between 1995 and 1997. We included women (n = 34,594) who had preterm PROM more than 12 hours and delivered between 23 and 32 weeks' gestation. Birth records were used to determine whether delivery occurred with or without labor. Infants with birth weights below the tenth percentile for gestational age were classified as small for gestational age (SGA) on the basis of a nomogram of all singleton births in the United States between 1995 and 1997. Primary outcomes were early neonatal (0-6 days), late neonatal (7-27 days), postneonatal (28-365 days), and infant death (0-365 days). Secondary outcomes included respiratory distress syndrome (RDS), assisted ventilation, and neonatal seizures. Risks of infant mortality and morbidity from labor were examined separately for SGA and non-SGA infants.

RESULTS

Overall rates were infant death 11.6%, RDS 15.1%, assisted ventilation 25.9%, and neonatal seizure 0.2%. Labor was associated with higher incidence of early neonatal death in SGA infants (adjusted relative risk [RR] 1.24, 95% confidence interval [CI] 1.11, 1.38) but had no effect on other outcomes. Among non-SGA infants, labor had no effect on infant death but was associated with higher rates of RDS (RR 1.15, 95% CI 1.08, 1.22) and assisted ventilation (RR 1.16, 95% CI 1.08, 1.24).

CONCLUSION

Although labor was associated with a slightly higher mortality rate in SGA infants and slightly more respiratory morbidity in non-SGA infants, recommendations regarding clinical treatment should await future clinical trials.

Outcome of prenatally diagnosed mild unilateral cerebral ventriculomegaly

The objective of this study was to determine the frequency of prenatally diagnosed unilateral cerebral ventriculomegaly and also to assess neonatal outcome in infants with this prenatal diagnosis. A computerized ultrasonography database identified fetuses with isolated and nonisolated unilateral cerebral ventriculomegaly from October 1994 to June 1999. The Denver II Developmental Screening Test was used to assess developmental skills. Unilateral cerebral ventriculomegaly was diagnosed in 15 of 21,172 (1 per 1,411) pregnancies. The width of the enlarged lateral ventricle ranged from 1.0 to 1.9 cm. In 10 (67%) of 15 cases unilateral cerebral ventriculomegaly was an isolated finding. Eight of the 14 infants who were born at 36 weeks' gestation or later had postnatal cranial imaging, and ventricular asymmetry was confirmed in 5 (63%). One infant with an arachnoid cyst and cerebral palsy died at 2 years of age. The remaining 11 infants in whom developmental milestones were assessed had age-appropriate skills. Unilateral fetal ventriculomegaly is usually an isolated finding and when isolated has little measurable effect on developmental outcome.

The bloodless blood knot

Just as it is difficult to describe adequately the exhilaration one feels when using a fly rod to land a trout caught from a mountain stream, there is also a tremendous amount of satisfaction in the successful completion of an obstetric operation. Until recently, we were woefully ignorant of how fly fishing expertise could benefit pregnancy. We report with great pride an instance in which fly fishing knot skill was essential to successful placement of a cervical cerclage for a woman with an incompetent cervix.

After-hours telephone calls to obstetrician-gynecologists

OBJECTIVE

To characterize the pattern, content, and management of after-hours telephone interactions between obstetrician-gynecologists and patients.

METHODS

In a prospective observational study, 12 resident and nine private physicians practicing obstetrics and gynecology completed data cards for after-hours telephone interactions with patients. Chief complaints were categorized as related to either women's health or primary care and on whether women were pregnant, postpartum, or not pregnant. Triage dispositions (evaluate now, office follow-up, or home care) were compared between groups. Women also were asked what they would have done if they had been unable to contact their physicians by telephone.

RESULTS

One hundred ninety-two of 276 calls evaluated (69. 6%) were from pregnant women, 20 (7.2%) were from postpartum women, and 64 (23.3%) were from nonpregnant women. Calls were related to primary care health issues in 24.1% (n = 45) of pregnant women, 40% (n = 8) of postpartum women, and 28.1% (n = 18) of nonpregnant women. There were no differences between residents and private physicians in the proportion of women triaged to immediate evaluation for pregnancy (35.1% [n = 40] versus 41.9% [n = 31], P =.74) or postpartum (11.1% [n = 1] versus 10% [n = 1],P =.96) problems. Among 139 women triaged to office follow-up, 41% (n = 57) would have come to the hospital for emergency evaluation if they had been unable to reach their physicians.

CONCLUSION

Resident and private obstetrician-gynecologists provide primary care and women's health care advice during after-hours telephone calls from patients. More than one third of after-hours telephone calls from pregnant women are triaged to immediate evaluation.

Cost-benefit analysis of prenatal diagnosis for Down syndrome using the British or the American approach

OBJECTIVE

To compare the cost and benefits of prenatal diagnosis for Down syndrome using the British and American approaches.

METHODS

This cost-benefit analysis was based on a decision-analytic approach. The British strategy included screening by a first-trimester ultrasound at 10-14 weeks for nuchal translucency thickness, and the American strategy included only second-trimester screening by using maternal age and maternal serum screening. The key probabilities of the decision-tree analysis and all cost estimates were based on American standards. The best scenario of the British strategy assumed ultrasound nuchal translucency thickness sensitivity (for detecting Down syndrome) of 80% and a false-positive rate of 5% and the worst scenario assumed a sensitivity of 50% and a false-positive rate of 10%. The results were expressed in annual costs based on approximately 4 million births per year in the United States.

RESULTS

As compared with do-nothing, the American strategy was found to allow savings of approximately $96 million per year and the best scenario for the British strategy was savings of approximately $5 million per year. The financial costs of the British and American strategies would be comparable only if the first-trimester ultrasound had a sensitivity of 80% and a false-positive rate of 5% in detecting Down syndrome.

CONCLUSION

The British strategy does not appear to be economically beneficial in the United States even under the most ideal scenarios of ultrasound accuracy.

Foot length in fetuses with abnormal growth

Sonographic fetal foot length is highly predictive of gestational age. In order to assess the reliability of this parameter in predicting gestational age in cases of abnormal fetal growth, we examined fetal foot length in small- and large-for-gestational-age fetuses. A nomogram of foot length versus gestational age between 15 and 37 weeks was constructed using cross-sectional data obtained from 5372 singleton fetuses. Fetal foot lengths for small-for-gestational-age fetuses (estimated fetal weight below the 10th percentile) and large-for-gestational-age fetuses (above the >90th percentile) fetuses were plotted against the foot length nomogram in order to determine the number of small-for-gestational-age fetuses and large-for-gestational-age fetuses with foot lengths below the 10th and above the 90th percentiles, respectively. Of the 586 small-for-gestational-age fetuses, 355 (60.6%) had foot lengths below the 10th percentile on the nomogram. When foot lengths from large-for-gestational-age fetuses were plotted on the foot length nomogram, 29.4% (219 of 744) had measurements above the 90th percentile. Fetal foot length can be influenced by growth restriction as well as states of accelerated fetal growth. Our findings imply that there are limitations to the use of fetal foot length for gestational age assessment, particularly in fetuses with growth abnormalities.

Routine second-trimester ultrasonography in the United States: a cost-benefit analysis

OBJECTIVE

The objective of this study was to perform a cost-benefit analysis of routine second-trimester screening ultrasonography in the United States as compared with performing ultrasonography only in the presence of indications.

STUDY DESIGN

It was assumed that 1 million pregnant women are available annually who otherwise would not have an indication for an ultrasonographic examination. Cost savings from early detection and therapeutic abortion were considered only for fetal conditions for which lifetime cost estimates are available, including spina bifida, major cardiac disease, cleft lip or palate, renal agenesis or dysgenesis, urinary obstruction, lower or upper limb reduction, omphalocele, gastroschisis, and diaphragmatic hernia. Two separate cost-benefit analyses were considered with the range of fetal anomaly detection rates before 24 weeks' gestation as reported by tertiary and non-tertiary centers in the Routine Antenatal Diagnostic Imaging with Ultrasound (RADIUS) trial. Potential cost savings from averting treatment for preterm labor and postdate gestations were also considered.

RESULTS

The ratio of savings to cost was between 1.35 and 1.70 (savings of $1.35-$1.70 per $1 spent) if the ultrasonographic examinations were performed in tertiary care centers. The ratio of savings to cost was between 0.40 and 0.74 (loss of $0.26-$0.60 per $1 spent) if the examinations were performed in nontertiary centers. If the screening ultrasonography was performed in tertiary centers, the expected annual net benefits were estimated at $97 to 189 million. If ultrasonographic screening was performed in nontertiary centers, the expected annual net losses were estimated at $69 to 161 million.

CONCLUSION

Routine second-trimester ultrasonographic screening appears to be associated with net benefits only if the ultrasonography is performed in tertiary care centers.

Clinical chorioamnionitis and histologic placental inflammation

OBJECTIVE

To estimate the rate of histologic chorioamnionitis in the presence of diagnosed clinical chorioamnionitis and determine whether clinical markers of maternal and neonatal infection are associated with histologic chorioamnionitis.

METHODS

We identified singleton pregnancies from 1996 in which discharge diagnoses included clinical chorioamnionitis and reviewed maternal and neonatal records for clinical evidence of chorioamnionitis and suspected or confirmed neonatal infections. Placentas were examined for acute histologic chorioamnionitis.

RESULTS

One hundred thirty-nine pregnancies with the discharge diagnosis of maternal clinical chorioamnionitis were included. Eighty-six (61.9%) had the clinical diagnosis supported by histologic chorioamnionitis. Histologic chorioamnionitis was associated with an earlier gestational age at delivery (35.7+/-6.5 weeks versus 38.6+/-2.9 weeks, P = .002), lower epidural usage (72.1% versus 92.5%, P = .004), less internal monitoring (47.7% versus 75.5%, P = .001), and possible neonatal sepsis (60.5% versus 35.8%, P = .005). For 19 of 71 (26.8%) infants with possible neonatal sepsis, placentas did not show histologic chorioamnionitis.

CONCLUSION

Clinical chorioamnionitis and possible neonatal infection were not supported by histologic evidence for infection in 38.1% and 26.8% of cases, respectively, suggesting other noninflammatory causes of signs and symptoms.

Indication-specific accuracy of second-trimester genetic ultrasonography for the detection of trisomy 21

OBJECTIVE

The object of this study was to determine whether there are any clinically significant indication-specific variations in the accuracy of second-trimester genetic ultrasonography and to provide a risk adjustment for fetal trisomy 21 according to the results of genetic ultrasonography.

STUDY DESIGN

From November 1, 1992, to September 30, 1998, a second-trimester genetic sonogram was offered to all pregnant women who were at an increased risk for fetal trisomy 21 (>/=1:274) because of either advanced maternal age (>/=35 years) or abnormal serum biochemical profile or both of these. Outcome information included the results of genetic amniocentesis if performed and the results of pediatric assessment and follow-up after birth. In determining diagnostic accuracy of the genetic sonogram the presence of >/=1 abnormal ultrasonographic marker was considered an abnormal test result.

RESULTS

A total of 1835 fetuses with known outcomes underwent genetic ultrasonography between 15 and 24 weeks' gestation; of these 1792 had normal results, 34 had trisomy 21, and 9 had other chromosomal abnormalities. The likelihood of fetal trisomy 21 was reduced by 80% after a normal result of genetic ultrasonography. The overall sensitivity, specificity, and positive and negative predictive values of genetic ultrasonography for the detection of trisomy 21 were 82%, 91%, 15%, and 99.6%, respectively. There were no significant indication-specific variations in the accuracy of second-trimester ultrasonography. The sensitivity for the detection of fetal trisomy 21 ranged from 80% among women with advanced maternal age to 100% among women with both an abnormal biochemical profile and advanced maternal age.

CONCLUSIONS

The likelihood of fetal trisomy 21 risk was reduced 80% after a normal result of genetic ultrasonography. In addition there were no significant indication-specific variations in the detection rate of genetic ultrasonography.

Value of maintenance therapy with oral tocolytics: a systematic review

OBJECTIVE

The objective was to perform a systematic review of prospective randomized trials evaluating the efficacy of oral tocolytics in the prevention of recurrent preterm labor and its associated complications.

METHODS

A MEDLINE search of English language articles published since 1966 was performed to identify studies of maintenance oral tocolytic therapy. Studies were included in the review which: 1) randomized patients to an oral tocolytic after stabilization with parenteral therapy; 2) reported results for either a placebo or a control group; and 3) included patients with intact membranes only. These studies were analyzed for nine outcomes, including incidence of preterm delivery, incidence of recurrent preterm labor, latency from treatment to delivery, gestational age, birthweight, admission to an intensive care nursery (ICN), incidence of respiratory distress syndrome (RDS), incidence of intraventricular hemorrhage (IVH), and perinatal mortality.

RESULTS

Seven studies met the inclusion criteria, four of which used oral terbutaline for the treatment arm (two had a control group, and two had a placebo group), and one used oral ritodrine (with a placebo group). Of the remaining two, one used oral ritodrine and oral magnesium chloride (with a control group), and the other used oral terbutaline and oral magnesium chloride (with a placebo group). The results of the individual studies suggest that there was no beneficial effect of oral tocolytic therapy on the incidence of preterm delivery (odds ratio (OR) range: 0.7-2.0), incidence of preterm labor recurrence (OR range: 0.6-3.2), ICN admission (OR range: 1.3-2.0), incidence of RDS (OR range 0.1-4.3), incidence of IVH (OR range 0.3-2.0), perinatal mortality (OR range: 1.6-4.3), or gestational age at delivery.

CONCLUSIONS

We concluded that a meta-analysis based on the available studies is not possible due to the fact that there is little that these seven studies have in common with respect to treatment comparisons. In addition, inconsistent definitions of outcome variables makes pooling this data inappropriate and invalid. Therefore, well-designed, large, randomized trials are needed to evaluate the efficacy of oral tocolytics in improving perinatal outcome.

Economic evaluation of prenatal carrier screening for fragile X syndrome

OBJECTIVE

The objective of this study was to conduct an economic evaluation of routine prenatal carrier testing for fragile X syndrome.

METHODS

This economic analysis was conducted from the societal perspective. A cost-benefit equation was developed based on the premise that the cost of routinely offering prenatal carrier testing for fragile X syndrome should be at least equal to, or less than, the cost of the current practice of not offering such testing. Sensitivity analyses included key assumptions regarding therapeutic abortion rates (50-100%) and patient screening acceptance rates (50-80%).

RESULTS

A policy of routinely offering prenatal carrier testing for fragile X syndrome may be beneficial only if the cost per screening test is less than $120 during the first year of the screening program, or less than $240 when the program reaches its full maturity. Given the current cost per screening test of $250, prenatal screening for carrier status for fragile X syndrome carries the potential for annual losses of approximately $10 to $195 million in the United States. In addition, approximately 46-115 fetal lives may be lost due to invasive genetic procedures.

CONCLUSIONS

Prenatal screening for fragile X syndrome may be economically beneficial only if the cost of the prenatal screening test for carrier identification is considerably less than the current cost.

Cost-benefit analysis of targeted ultrasonography for prenatal detection of spina bifida in patients with an elevated concentration of second-trimester maternal serum alpha-fetoprotein

OBJECTIVE

The objectives of this study were to examine (1) the diagnostic accuracy requirements (from the cost-benefit point of view) of targeted ultrasonography versus genetic amniocentesis for prenatal detection of spina bifida in women with an elevated level of maternal serum alpha-fetoprotein, (2) the ultrasonographic accuracy of previously published studies from the cost-benefit point of view, and (3) the possible economic impact for the United States of offering targeted ultrasonography instead of routine amniocentesis to this group of patients.

STUDY DESIGN

Our cost-benefit formula was based on the hypothesis that the cost of universal genetic amniocentesis in patients with an elevated concentration of maternal serum alpha-fetoprotein in the second trimester should be at least equal to the cost of universal targeted ultrasonography, with amniocentesis used only for those with abnormalities on a sonogram. The main components of the formula included the diagnostic accuracy of targeted ultrasonography (sensitivity and specificity for detecting spina bifida), the cost of the amniocentesis package, the cost of targeted ultrasonography, and the lifetime cost of spina bifida not detected by targeted ultrasonography. After appropriate manipulation of the formula, a graph was constructed to represent the balance between the sensitivity and false-positive rate of targeted ultrasonography and was used to examine the accuracy of previously published ultrasonographic studies from the cost-benefit point of view. Sensitivity analyses included a range of prevalences of spina bifida in women with elevated maternal serum alpha-fetoprotein from 1:50 to 1:200 and false-positive rates of targeted ultrasonography from 1% to 10%.

RESULTS

Assuming overall prevalences of spina bifida of 1:50, 1:100, or 1:200 among women with elevated maternal serum alpha-fetoprotein, we found targeted ultrasonography to be beneficial only if the overall sensitivities for detecting fetal spina bifida were >88%, >76%, and >51%, respectively. All 17 studies published after the mid-1980s, which used the "cranial signs" for detecting spina bifida, had accuracies compatible with economic benefits (sensitivities, 92% to 100%; false-positive rates, 0% to 3%).

CONCLUSION

The benefit of second-trimester targeted ultrasonography for fetal spina bifida depends on diagnostic accuracy (ie, sensitivity and false-positive rate). Currently achieved ultrasonographic accuracies are compatible with net benefits. Targeted ultrasonography in patients with an elevated level of second-trimester maternal serum alpha-fetoprotein in the United States has the potential for annual savings of approximately $36 million to $49 million and for avoiding 268 fetal deaths.

Maternal chorioamnionitis and umbilical vein interleukin-6 levels for identifying early neonatal sepsis

OBJECTIVE

The purpose of this study was to determine whether elevated levels of umbilical vein IL-6 would be a better marker for early neonatal sepsis than the clinical signs of maternal chorioamnionitis.

METHODS

Patients delivering preterm because of spontaneous preterm labor or premature rupture of the membranes were evaluated for clinical signs of chorioamnionitis, which was defined as a temperature of > or =100.4 degrees F along with > or =2 of the following: significant maternal tachycardia (> or = 120 bpm), fetal tachycardia (> or =160 bpm), purulent discharge, uterine tenderness, and leukocytosis (WBC > or =18,000 cells/mm3). Umbilical vein blood was assayed for interleukin-6. An elevated interleukin-6 level was determined to be 25 pg/mL. Infants were evaluated for evidence of early neonatal sepsis. The abilities of clinical chorioamnionitis and interleukin-6 levels > or =25 pg/mL to predict early neonatal sepsis were compared.

RESULTS

There were 28 patients delivering 14 (50%) neonates with evidence for early neonatal sepsis. The incidence of suspected neonatal sepsis in women with and without clinical chorioamnionitis was 6/10 (60%) vs. 8/18 (44.4%), P = 0.43. Using receiver operator characteristic curves, the best cutoff for interleukin-6 was found to be 25 pg/mL. The compared sensitivity, specificity, and positive and negative predictive values of clinical chorioamnionitis vs. interleukin-6 levels > or =25 pg/mL for predicting early neonatal sepsis were 42.9% vs. 92.9%, 71.4% vs. 92.9%, 60% vs. 92.9%, and 55.6% vs. 92.9%, respectively.

CONCLUSIONS

Elevated umbilical vein levels of interleukin-6 predict those preterm infants with early sepsis better than the presence of clinical chorioamnionitis.

Comparison of three sonographic circumference measurement techniques to predict birth weight

OBJECTIVE

To compare the accuracy of three different sonographic circumference measurement techniques in predicting birth weight in term fetuses, using a standard equation for estimating fetal weight.

METHODS

Fifty-three singleton, term fetuses were examined sonographically within 24 hours of scheduled elective cesarean delivery. The biparietal diameter (BPD) and femur length (FL) were measured using standard techniques, and head circumference (HC) and abdominal circumference (AC) were measured using three separate circumference measurement techniques (Two-diameter, ellipse, and trace). With the use of each circumference method, estimated fetal weights were determined for each fetus according to a weight-estimation formula incorporating BPD, HC, AC, and FL. The accuracy of the formula using each circumference measurement technique for predicting actual birth weight was calculated.

RESULTS

The mean (+/- standard deviation [SD]) gestational age was 38.1 +/- 0.9 weeks and the mean actual birth weight was 3536 +/- 472 g. The two-diameter and ellipse circumference measurements allowed more accurate birth weight prediction than did the trace method, with mean (+/- SD) percent deviations from the actual birth weight of -0.5 +/- 7.8%, 1.9 +/- 8.0%, and 8.2 +/- 11.6% (P < .05), respectively. The trace method was the least accurate, with a mean birth weight overestimation of 266 g and measurements within 10% of the actual birth weight only 49.1% of the time. The two-diameter and ellipse method yielded predicted birth weights within 10% of actual birth weights in 77.4 and 79.2% of cases, respectively.

CONCLUSION

Two-diameter and ellipse circumference measurement techniques are similarly accurate in predicting birth weight and both are significantly better than the trace technique.

Incidence of placental abruption in relation to cigarette smoking and hypertensive disorders during pregnancy: a meta-analysis of observational studies

OBJECTIVE

To systematically review the literature and summarize the relationship between cigarette smoking and placental abruption, and to evaluate the joint influences of smoking and hypertensive disorders (chronic hypertension and preeclampsia) on the subsequent development of abruption.

DATA SOURCES

We reviewed studies identified through a MEDLINE literature search between 1966 and 1997 and through studies cited in the references of published reports.

METHODS OF STUDY SELECTION

A total of 13 observational (seven case-control and six cohort) studies were identified which included a total of 1,358,083 pregnancies. We excluded case reports on placental abruption, and restricted the literature search to studies published in English. A meta-analysis was performed by computing pooled odds ratios based on random-effects models describing the association between placental abruption, smoking, and hypertensive disorders. Potential sources of heterogeneity among these studies were explored in detail.

TABULATION, INTEGRATION, AND RESULTS

The overall incidence of placental abruption was 0.64% (8724 of 1,358,623). Smoking was associated with a 90% increase in the risk of placental abruption (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.8, 2.0). This pattern was consistent by study design (case-control compared with cohort studies) and smoking prevalence (low compared with high prevalence, defined as less than 30% compared with 30% or more, respectively). However, the association was significantly (p < .001) stronger among the seven studies conducted outside the United States (OR 2.1, 95% CI 2.0, 2.2), compared with the six studies conducted in the United States (OR 1.6, 95% CI 1.5, 1.8). Pooled population attributable risk percentage for each stratum ranged between 15% and 25%, implying that 15-25% of placental abruption episodes are attributable to cigarette smoking. Data on the dose-response relationship between number of cigarettes smoked per day and the risk of abruption indicate that the OR increased with increasing number of cigarettes smoked. Furthermore, a meta-analysis of the joint effects of smoking and hypertension during pregnancy on the development of abruption identified two published studies, including 102,609 pregnancies. In the presence of smoking, the risk of abruption was further increased due to chronic hypertension, mild or severe preeclampsia, or chronic hypertension with superimposed preeclampsia.

CONCLUSION

Our meta-analyses showed an increased risk for placental abruption in relation to both cigarette smoking and hypertensive disorders during pregnancy. Because cigarette smoking is a modifiable risk factor, and hypertensive disorders are potentially treatable if diagnosed early in pregnancy, patient education, smoking cessation programs, and early prenatal care may be important factors in the prevention of placental abruption.

An economic evaluation of prenatal strategies for detection of trisomy 18

OBJECTIVE

The objective of this study was to perform an economic evaluation of prenatal diagnostic strategies for women who are at increased risk for fetal trisomy 18 caused by either fetal choroid plexus cysts discovered in a conventional sonogram or an abnormal triple screen.

STUDY DESIGN

The prevalence of trisomy 18 in the presence of second-trimester fetal choroid plexus cysts and also in the presence of abnormal triple screen were made on the basis of previously reported studies. A cost/benefit analysis and cost-effectiveness determination of 3 strategies were performed: (1) no prenatal diagnostic workup of at-risk patients, (2) universal genetic amniocentesis of all at-risk patients, and (3) universal second-trimester targeted genetic ultrasonography of all at-risk patients with amniocentesis (for fetal karyotyping) reserved only for those with abnormal ultrasonography results.

RESULTS

The strategy of no prenatal diagnostic workup was the least expensive approach, costing $1,650,000 annually in the United States. The more costly approach was the strategy of universal amniocentesis for detecting fetal trisomy 18 in the presence of either second-trimester choroid plexus cysts or abnormal maternal serum screening, generating an annual cost of approximately $12 million and 40 fetal losses as a result of amniocenteses. The strategy of targeted genetic ultrasonography generated an annual cost of only $5 million and 8 fetal losses as a result of amniocenteses.

CONCLUSIONS

Routine second-trimester amniocentesis in patients at increased risk for fetal trisomy 18 caused by either the presence of fetal choroid plexus cysts or abnormal triple screening is not justified from the cost/benefit point of view.

An economic evaluation of second-trimester genetic ultrasonography for prenatal detection of down syndrome

OBJECTIVE

The objective of this study was to perform an economic evaluation of second-trimester genetic ultrasonography for prenatal detection of Down syndrome. More specifically, we sought to determine the following: (1) the diagnostic accuracy requirements (from the cost-benefit point of view) of genetic ultrasonography versus genetic amniocentesis for women at increased risk for fetal Down syndrome and (2) the possible economic impact of second-trimester genetic ultrasonography for the US population on the basis of the ultrasonographic accuracies reported in previously published studies.

STUDY DESIGN

A cost-benefit equation was developed from the hypothesis that the cost of universal genetic amniocentesis of patients at increased risk for carrying a fetus with Down syndrome should be at least equal to the cost of universal genetic ultrasonography with amniocentesis used only for those with abnormal ultrasonographic results. The main components of the equation included the diagnostic accuracy of genetic ultrasonography (sensitivity and specificity for detecting Down syndrome), the costs of the amniocentesis package and genetic ultrasonography, and the lifetime cost of Down syndrome cases not detected by the genetic ultrasonography. After appropriate manipulation of the equation a graph was constructed, representing the balance between sensitivity and false-positive rate of genetic ultrasonography; this was used to examine the accuracy of previously published studies from the cost-benefit point of view. Sensitivity analyses included individual risks for Down syndrome ranging from 1:261 (risk of a 35-year-old at 18 weeks' gestation) to 1:44 (risk of a 44-year-old at 18 weeks' gestation). This economic evaluation was conducted from the societal perspective.

RESULTS

Genetic ultrasonography was found to be economically beneficial only if the overall sensitivity for detecting Down syndrome was >74%. Even then, the cost-benefit ratio depended on the corresponding false-positive rate. Of the 7 published studies that used multiple ultrasonographic markers for genetic ultrasonography, 6 had accuracies compatible with benefits. The required ultrasonographic accuracy (sensitivity and false-positive rate) varied according to the prevalence of Down syndrome in the population tested.

CONCLUSIONS

The cost-benefit ratio of second-trimester genetic ultrasonography depends on its diagnostic accuracy, and it is beneficial only when its overall sensitivity for Down syndrome is >74%.

Fetal hydrops in the first trimester associated with maternal parvovirus infection

We present a case of fetal hydrops associated with maternal parvovirus infection during the first trimester of pregnancy that sonographically mimicked findings associated with fetal aneuploidy. The transabdominal sonograms of this fetus at 12.9 weeks' gestational age were consistent with increased nuchal translucency thickness. Transvaginal sonographic evaluation of the fetus showed generalized subcutaneous sonolucency suggestive of early fetal hydrops. An etiologic evaluation identified serologic evidence of recent maternal parvovirus infection and a normal karyotype. The pregnancy ended in fetal demise. Our findings suggest that visualization of nuchal translucency thickening in the first trimester should prompt a complete sonographic evaluation for fetal hydrops, which, if identified, should lead to serologic evaluation for parvovirus infection.

Standards of birth weight in twin gestations stratified by placental chorionicity

OBJECTIVE

To establish fetal growth nomograms for twin gestations, categorized by placental chorionicity, and to compare them with those of published singleton and twin nomograms.

METHODS

Computerized data files of live births of all twins delivered between January 1990 and October 1996 at Saint Peter's Medical Center were used. Birth weight curves corresponding to the fifth, tenth, 50th, 90th, and 95th percentiles were derived separately for twins with monochorionic and dichorionic placentation. We generated the curves by applying the method of generalized estimating equations, after adjusting for the potential intracluster correlation due to twinning. The curves were then smoothed on the basis of nonparametric restricted cubic splines to derive (smoothed) birth weight percentiles. We then compared our twin birth weight nomogram to six previously published singleton and two twin nomograms published previously for predicting small for gestational age infants (defined as birth weight below the tenth percentile).

RESULTS

Among 1302 twin fetuses, 272 (21%) were monochorionic. Twins from monochorionic gestations weighed, on average, 66.1 g (standard deviation 28.4 g, P = .02) less than twins from dichorionic gestations after correcting for gestational age. Twin curves based on parity (nulliparity versus multiparity) were not different from each other. Analyses indicate that all previously published singleton nomograms approximate twin growth reasonably well between 32 and 34 weeks, but they underestimate twin growth at earlier gestational ages (between 25 and 32 weeks) and overestimate twin growth beyond 34 weeks' gestation. Similarly, a comparison of previously published twin nomograms with those of ours indicates that the growth standards in our population were similar to those in other published twin nomograms.

CONCLUSION

We recommend that future epidemiologic and clinical studies use twin nomograms to identify growth-restricted twin fetuses. Moreover, because fetal growth is influenced by placental chorionicity, we recommend that fetal growth assessment in twin gestations consider placental chorionicity, whenever the information is available.

A cost-effectiveness analysis of prenatal carrier screening for cystic fibrosis

OBJECTIVE

To examine the cost-effectiveness of prenatal carrier screening for cystic fibrosis.

METHODS

A cost-benefit equation was developed that was based on the hypothesis that the cost of prenatal diagnosis required to diagnose and prevent one case of cystic fibrosis should be equal to or less than the lifetime cost generated from the birth of a neonate with cystic fibrosis. The formula was adjusted because a woman's positive or negative carrier status remains unchanged, thus eliminating the need for testing in subsequent pregnancies. The formula was manipulated to identify the optimal cost per screening test, as well as the net cost savings per prenatally diagnosed case of cystic fibrosis for various racial or ethnic groups. Sensitivity analyses included some key assumptions regarding the cost per screening test ($50-150), patient screening acceptance rates (25-100%), and therapeutic abortion rates (50-100%).

RESULTS

Assuming therapeutic abortion rates of 50-100%, the net savings per prenatally diagnosed case of cystic fibrosis are $58,369-$382,369 among whites. Given the previously reported patient screening acceptance rates of 50-78%, the overall annual cost savings in the United States for whites are $161-251 million. However, the screening program was not found to be cost-effective for blacks, Asians, or Hispanics.

CONCLUSION

Under most assumptions and sensitivity analyses, a prenatal cystic fibrosis-carrier screening program appears to be cost-effective.

An economic evaluation of first-trimester genetic sonography for prenatal detection of Down syndrome

OBJECTIVE

To determine 1) the diagnostic accuracy requirements of first-trimester genetic sonography from the cost-benefit point of view and 2) the economic impact of first-trimester genetic sonography for the United States on the basis of the accuracy of previously published studies.

METHODS

A cost-benefit equation was developed on the basis of the hypothesis that the cost of chorionic villus sampling (CVS) in pregnant women with advanced maternal age (at least 35 years old) should be at least equal to the cost of genetic sonography with CVS used only for those with abnormal ultrasound results. The components of the equation included the diagnostic accuracy of genetic ultrasound (sensitivity and specificity for detecting Down syndrome), the costs of the CVS package and genetic ultrasound, and the lifetime cost of Down syndrome cases.

RESULTS

First-trimester genetic sonography was found to be beneficial if the overall sensitivity for detecting Down syndrome was greater than 70%, and even then, the cost-benefit ratio depended on the corresponding false-positive rate. The required minimum ultrasound sensitivity varied according to the maternal age-specific prevalence of Down syndrome and ranged between 40% (for women 35 years old) to 96% (for women 44 years old). Of eight published cohorts using nuchal translucency thickness for genetic sonography, five had accuracies of genetic ultrasound compatible with net benefits.

CONCLUSION

The benefits of first-trimester genetic sonography depend on its diagnostic accuracy. First-trimester genetic sonography has the potential for annual savings of 22 million dollars in the United States.

In utero intraventricular hemorrhage and growth discordancy in a quadruplet pregnancy

With the advent of real-time ultrasonography, there have been a number of reported cases of in utero fetal intraventricular hemorrhage. The most frequent etiology for this uncommon event is iso/allo-immune thrombocytopenia; however, other risks have also been identified. This is the first report of an in utero diagnosis of intraventricular hemorrhage in a multiple gestation. Severe growth discordancy in this quadruplet pregnancy was an associated finding.

Effects of placental delivery method and intraoperative glove changing on postcesarean febrile morbidity

This study was designed to evaluate the effects of the placental delivery methods and intraoperative glove changing on postcesarean febrile morbidity. In this randomized controlled trial, consenting patients were randomized to one of four management protocols: Group A (n = 26)--no glove change with manual placental delivery; Group B (n = 27)--no glove change with expressed placental delivery; Group C (n = 27)--glove change with manual placental delivery; and Group D (n = 28)--glove change with expressed placental delivery. Glove change was performed by removal of a second glove after delivery of the fetal head. Variables examined included febrile morbidity, endometritis, maximums and durations of elevated temperatures, as well as other demographic, intrapartum, and postpartum variables. Febrile morbidity and endometritis rates were not significantly different between the four groups. When the groups were combined so as to compare no glove change versus glove change (Groups A and B vs. C and D) and manual versus expressed placental delivery (Groups A and C vs. B and D), there were no significant differences in either febrile morbidity (relative risk: 0.7, 95% CI: 0.3-1.4 and relative risk: 1.4, 95% CI: 0.6-3.5) or endometritis (relative risk: 1.2, 95% CI: 0.5-2.8 and relative risk: 1.5, 95% CI: 0.6-3.6), respectively. There were no statistically significant differences in measures of postcesarean febrile morbidity based on placental delivery method or intraoperative glove change.

The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis

OBJECTIVE

Our purpose was to determine the incidence of placenta previa based on the available epidemiologic evidence and to quantify the risk of placenta previa based on the presence and number of cesarean deliveries and a history of spontaneous and induced abortion.

STUDY DESIGN

We reviewed studies on placenta previa published between 1950 and 1996 on the basis of a comprehensive literature search with use of MEDLINE and by identifying studies cited in the references of published reports. Studies were chosen for inclusion in the metaanalysis if the incidence of placenta previa and its cross-classification with either prior cesarean delivery or abortions (both spontaneous and induced) or both were available. We also extracted details about the study design (case-control or cohort study) and place where they were conducted (United States or other countries). Published case reports dealing with placenta previa and studies relating to abruptio placentae were excluded from this review. We also restricted the search to studies published in English. No attempts were made to locate any unpublished studies. Data from studies identified during the literature search were reviewed and abstracted by a single author. In case of discrepancies or when the information presented in a study was unclear, abstraction by a (blinded) second reviewer was sought to resolve the discrepancy.

RESULTS

Data on the incidence of placenta previa and its associations with previous cesarean delivery and abortions were abstracted. Subgroup analyses were performed to identify potential sources of heterogeneity by study design and place where they were conducted. Statistical methods used for the metaanalysis included the fixed-effects logistic regression model, whereas potential sources of heterogeneity among studies were evaluated by fitting random-effects models. The tabulation of 36 studies identified a total of 3.7 million pregnant women, of whom 13,992 patients were diagnosed with placenta previa. The reported incidence of placenta previa ranged between 0.28% and 2.0%, or approximately 1 in 200 deliveries. Women with at least one prior cesarean delivery were 2.6 (95% confidence interval 2.3 to 3.0) times at greater risk for development of placenta previa in a subsequent pregnancy. The results varied by study design, with case-control studies showing a stronger relative risk (relative risk 3.8, 95% confidence interval 2.3 to 6.4) than cohort studies did (relative risk 2.4, 95% confidence interval 2.1 to 2.8). Four studies, encompassing 170,640 pregnant women, provided data on the number of previous cesarean deliveries. These studies showed a dose-response pattern for the risk of previa on the basis of the number of prior cesarean deliveries. Relative risks were 4.5 (95% confidence interval 3.6 to 5.5) for one, 7.4 (95% confidence interval 7.1 to 7.7) for two, 6.5 (95% confidence interval 3.6 to 11.6) for three, and 44.9 (95% confidence interval 13.5 to 149.5) for four or more prior cesarean deliveries. Women with a history of spontaneous or induced abortion had a relative risk of placenta previa of 1.6 (95% confidence interval 1.0 to 2.6) and 1.7 (95% confidence interval 1.0 to 2.9), respectively. Substantial heterogeneity in the results of the metaanalysis was noted among studies.

CONCLUSION

There is a strong association between having a previous cesarean delivery, spontaneous or induced abortion, and the subsequent development of placenta previa. The risk increases with number of prior cesarean deliveries. Pregnant women with a history of cesarean delivery or abortion must be regarded as high risk for placenta previa and must be monitored carefully. This study provides yet another reason for reducing the rate of primary cesarean delivery and for advocating vaginal birth for women with prior cesarean delivery.

A randomized placebo-controlled evaluation of terbutaline for external cephalic version

OBJECTIVE

To evaluate the efficacy of subcutaneous terbutaline therapy on the success rate of external cephalic version in term gestation.

METHODS

Women with singleton noncephalic gestations were assigned randomly to receive either terbutaline (0.25 mg) or placebo. Physicians were blinded to the assignment. Fifteen to 30 minutes after the study drug was administered, external cephalic version was attempted. It was discontinued after three attempts, for patient discomfort, for fetal heart rate decelerations, or when successful. Patients were discharged home after the procedure and allowed to enter spontaneous labor. Primary outcomes evaluated included initial success of version, presentation in labor, and route of delivery.

RESULTS

One hundred three women were enrolled in the study between January 1994 and June 1995, of whom 52 were assigned to terbutaline and 51 to placebo. External cephalic version was successful in 27 of 52 (52%) women receiving terbutaline compared with 14 of 51 (27%) of those receiving placebo (P = .019). This comparison yielded a relative risk (RR) of 1.9 (95% confidence interval [CI] 1.3, 6.5). Four of the 27 (15%) successful versions in the terbutaline group and three of the 14 (21%) successful versions in the placebo group spontaneously reverted to breech presentation. Ultimately, in labor there were 24 (46%) cephalic presentations in the terbutaline group and 13 (25%) in the placebo group (P = .048, RR 1.84, 95% CI 1.1, 5.8). Cesarean delivery rates were 11 of 41 (27%) for women with successful versions and 58 of 62 (94%) among those with failed versions (P < .001).

CONCLUSION

Terbutaline (0.25 mg) administered subcutaneously before an attempted version in women at term with noncephalic presentations significantly increased the initial success rate of version and the rate of cephalic presentations in labor while decreasing the rate of cesarean delivery.

Value of umbilical artery and vein levels of interleukin-6 and soluble intracellular adhesion molecule-1 as predictors of neonatal hematologic indices and suspected early sepsis

This study was designed to evaluate the relationship of suspected early neonatal sepsis to umbilical artery and vein levels of interleukin-6 (IL-6) and soluble intracellular adhesion molecule-1 (sICAM-1). Umbilical artery and vein samples from 17 preterm and 6 term pregnancies were assayed for IL-6 (pg/ml) and sICAM-1 (ng/ml). Neonates were categorized as having probable or suspected sepsis vs. no sepsis within 3 days of birth. Levels of IL-6 and sICAM-1 were evaluated based on sepsis status. Neonatal hematologic parameters were correlated with umbilical artery (ua) and vein (uv) levels of IL-6 and sICAM-1. Sensitivity, specificity, positive and negative predictive values for detecting neonates having probable or suspected early sepsis were calculated. There were significant differences of IL-6 levels between suspected sepsis and no infants in the umbilical artery (P < 0.002) and vein (P < 0.0001). The sensitivity, specificity, positive and negative predictive values for detection of suspected early neonatal sepsis using umbilical artery IL-6 levels > 7 pg/ml were 88.5%, 66.6%, 58.8%, 91%, and for umbilical vein levels > 7 pg/ml these values were 88.5%, 93.3%, 88.5%, and 93.3%. Umbilical artery and vein IL-6 levels correlated with both absolute band counts and immature/total neutrophil ratios. sICAM-1 levels were not affected by designated sepsis status. Umbilical cord blood IL-6 (but not sICAM-1) is potentially useful as a marker for suspected early neonatal sepsis.

Choice of second-trimester genetic sonogram for detection of trisomy 21

OBJECTIVE

To determine the utilization rate of second-trimester genetic sonogram and its role in influencing the decision for amniocentesis in women at increased risk for fetal trisomy 21.

METHODS

From November 1, 1993, to December 31, 1996, a second-trimester genetic sonogram or only genetic amniocentesis (as a first choice) were offered to pregnant women referred to our institution who were at increased risk for fetal trisomy 21.

RESULTS

During the study period, 2089 women were referred to our unit for genetic prenatal diagnosis; of these, 1426 (68%) chose only genetic amniocentesis, and 663 (32%) chose a genetic sonogram as their first option. The yearly utilization rates of genetic sonogram were two of 477 or 0.4% for 1993, 82 of 495 or 16.6% for 1994, 251 of 523 or 48.0% for 1995, and 328 of 594 or 55.2% for 1996. Adjusting for potential confounders, multivariable logistic regression analysis showed that the most important factors associated with the women's decision to undergo genetic amniocentesis were three or more ultrasound markers present (relative risk [RR] 189.5, 95% confidence interval [CI] 37.1, 980.0), two ultrasound markers present (RR 47.2, 95% CI 9.8, 267.8), one ultrasound marker present (RR 12.7, 95% CI 5.5, 29.7), and abnormal serum biochemistry (RR 3.0, 95% CI 1.0, 8.9).

CONCLUSION

The increasing utilization trend, in conjunction with the fact that an abnormal sonogram was the most influential factor in women's decision to undergo genetic amniocentesis, suggests that genetic sonogram services for detection of trisomy 21 should be added to the armamentarium of all prenatal diagnostic centers.

Second-trimester ultrasound markers for detection of trisomy 21: which markers are best?

OBJECTIVE

To investigate which second-trimester ultrasound markers for aneuploidy are the most diagnostically efficient in detecting fetal trisomy 21.

METHODS

All second-trimester genetic sonograms performed since November 1, 1992 for women at increased risk for fetal trisomy 21 were analyzed retrospectively. Statistical analysis included descriptive statistics, the test of proportions, and univariate and multivariable logistic regression analysis using trisomy 21 as the dependent variable and ten aneuploidy ultrasound markers as independent variables.

RESULTS

There were 581 normal fetuses, 23 with trisomy 21 and four with other chromosomal abnormalities. When one or more abnormal ultrasound markers were present, the sensitivity and false-positive rate for trisomy 21 were 87% and 13.4%, respectively. After adjusting for confounders, multivariate logistic regression analysis showed the best combination of ultrasound markers for detecting trisomy 21 to be nuchal fold thickening (relative risk [RR] 85.5; 95% confidence interval [CI] 20.4, 357.7), pyelectasis (RR 25.2; 95% CI 6.7, 95.0), and short humerus (RR 20.4; 95% CI 4.5, 92.1). The model combining these three ultrasound markers yielded a sensitivity of 87% and a false-positive rate of 6.7%.

CONCLUSION

By using only three ultrasound markers (combination of nuchal fold thickening, pyelectasis, and short humerus) the false-positive rate is decreased from 13.4% to 6.7% without any compromise in the sensitivity (87%). The clinical usefulness of evaluating the various second-trimester ultrasound markers needs to be evaluated in prospective studies.

Intrauterine growth and ultrasound findings in fetuses with Beckwith-Wiedemann syndrome

OBJECTIVE

To assess intrauterine growth in a series of nine fetuses diagnosed with Beckwith-Wiedemann syndrome.

METHODS

Infants confirmed postnatally to have Beckwith-Wiedemann syndrome were identified from records maintained in the Division of Clinical Genetics. Antenatal ultrasound and birth records were evaluated. Head circumference (HC), abdominal circumference (AC), and estimated fetal weight (EFW) were assigned percentiles based on gestational age. Newborn HC and birth weight were also assigned percentiles. Polyhydramnios was diagnosed using either amniotic fluid index or documented subjective assessment.

RESULTS

Nine infants with Beckwith-Wiedemann syndrome had antenatal ultrasound examinations. Seven of these had more than one examination. Two infants were suspected to have Beckwith-Wiedemann syndrome in utero. Important ultrasound findings included omphalocele (four), enlarged liver and kidneys (one), and enlarged liver (one). Fetal tongue protrusion on ultrasound was not identified in any fetus. Six of nine fetuses (66%) with ultrasound examinations after 25 weeks' gestation had polyhydramnios. Evaluation of the fetal HC, AC, and EFW percentiles demonstrated that fetuses with Beckwith-Wiedemann syndrome may exhibit accelerated growth as early as 25-30 weeks' gestation, but may exceed the 90th percentile only after 36 weeks' gestation.

CONCLUSIONS

Fetuses with omphalocele, polyhydramnios, and an AC less than the 90th percentile may have Beckwith-Wiedemann syndrome. Polyhydramnios and accelerated growth beginning between 25 and 36 weeks' gestation, even without omphalocele, should alert the physician to the possibility of Beckwith-Wiedemann syndrome.

Epidemiology of antepartum fetal testing

Advances in perinatal and neonatal health care over the past few decades have resulted in a substantial reduction in perinatal mortality. Some of this improvement has been attributed to antepartum fetal surveillance techniques. The primary objective of antepartum fetal surveillance techniques is to avoid fetal deaths. An ideal secondary objective is to avoid neonatal complications related to intrauterine asphyxia. In this article, some of the difficulties in evaluating existing antepartum fetal surveillance techniques are highlighted. Some of the epidemiological methods for evaluating a screening test are reviewed and their importance discussed with reference to fetal testing procedures. Lastly, the possibility of considering indication-specific fetal testing to improve perinatal morbidity is examined.

Correlation between umbilical artery and vein levels of interleukin-6 and soluble intracellular adhesion molecule-1

This study was designed to determine whether umbilical artery levels of both interleukin-6 (IL-6) and soluble intracellular adhesion molecule-1 (sICAM-1) correlate with levels in the umbilical vein. Paired umbilical artery-vein specimens were assayed for IL-6 and sICAM-1. The paired-sign test was used to compare umbilical artery vein levels of IL-6 and sICAM-1. Spearman rank correlation was used to determine relationships between paired umbilical artery-vein levels for a variety of clinical subgroups. For 23 paired samples overall, umbilical artery levels were greater than corresponding vein levels for both IL-6 (P = .039) and sICAM-1 (P = .035). Artery-vein correlations were significant for IL-6 (rho = 0.845, P = .001) and sICAM-1 (rho = 0.806, P = .0002). Correlations were not influenced by prematurity, route of delivery, labor, or neonatal sepsis. In conclusion, umbilical artery levels of IL-6 and sICAM-1 correlate significantly with umbilical vein levels.