Faculty Bibliography

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

Uterine rupture can occur at any time throughout gestation. We present a woman with a previous Cesarean section followed by an abdominal pregnancy. In her next pregnancy, complete uterine rupture resulted in an emergency laparotomy. This case is unique in that it gives insight into the variable presentations of uterine rupture and the risks associated with prior Cesarean sections.

OBJECTIVE:To compare the genetic risk assessment of the referring obstetrician to the risk assessment of the genetic counselor. STUDY DESIGN/METHODS:All patients evaluated between January 1, 1999, and March 31, 1999, and who required genetic counseling were retrospectively reviewed. The genetic risk assessment of the referring obstetrician was compared to the genetic risk assessment following counseling by a genetic counselor who used a questionnaire and a three-generation pedigree. The number of patients with additional genetic risk factors identified by the genetic counselor were recorded and compared by using the McNemar chi-square test. Group demographics and characteristics were evaluated. RESULTS:Among the 145 patients evaluated, 38% (n = 55) had additional genetic risk factors detected by the genetic counselor (P =.01). The maternal demographics and characteristics did not differ between the two groups. CONCLUSION/CONCLUSIONS:The practice of referring high-risk obstetric patients for genetic counseling improves the detection of identifiable genetic risk factors.

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/METHODS: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/CONCLUSIONS: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.

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

OBJECTIVES: To assess the role of cervical sonography and to compare various sonographic cervical parameters in their ability to predict spontaneous preterm birth in high-risk singleton gestations. DESIGN: A prospective cohort of 469 high-risk gestations were longitudinally evaluated between 15 and 24 weeks' gestation on 1265 occasions with transvaginal cervical sonography and transfundal pressure. The cervical parameters obtained were funnel width and length, cervical length, percent funneling and cervical index. The information obtained was used for patient management. Restriction of physical activities was initiated at cervical lengths of < or = 2.5 cm with cerclage as an option for cervical lengths of < or = 2.0 cm. RESULTS: Receiver operating characteristic curve analyses showed that a cervical length of < or = 2.5 cm between 15 and 24 weeks' gestation was equal to the other sonographic cervical parameters in its ability to predict spontaneous preterm birth. The sensitivities for delivery at < 28, < 30, < 32 and < 34 weeks' gestation were 94%, 91%, 83% and 76%, respectively, while the negative predictive values were 99%, 99%, 98% and 96%, respectively. The placement of a cerclage did not influence the positive and negative predictive values. In comparison to women with other risk factors, cervical length was best in the prediction of preterm birth in women with a prior mid-trimester loss; an optimal cut-off of < or = 1.5 cm had sensitivities for delivery at < 28, < 30, < 32 and < 34 weeks' gestation of 100%, 100% 92% and 81%, respectively. The rate of preterm delivery at < 34 weeks' gestation increased dramatically when the cervical length was < or = 1.5 cm. Cervical length was the only independent variable that entered the logistic regression model for the prediction of preterm delivery at < 34 weeks' gestation. CONCLUSIONS: In high-risk singleton gestations a cervical length of < or = 2.5 cm was equal to other sonographic cervical parameters in its ability to predict spontaneous preterm birth and was better for the prediction of earlier forms of prematurity (at < 28 and < 30 weeks) than later forms (at < 32 and < 34 weeks). The optimal cervical lengths and their performance for predicting prematurity may be influenced by obstetric risk factors

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/CONCLUSIONS: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.

OBJECTIVE:To compare the frequency of visualization of echogenic intracardiac foci in different cardiac views. METHODS:Women having ultrasonographic examinations between October 1997 and July 1998 were prospectively evaluated if a fetal echogenic intracardiac focus was seen in either ventricle. RESULTS:Echogenic intracardiac foci were seen in 89 fetuses in whom both the apical and lateral 4-chamber heart views were obtained. Eight-six fetuses (97%) had a single focus (83 in the left ventricle and 3 in the right ventricle), and 3 (3%) had 2 foci. Echogenic intracardiac foci were seen in the apical 4-chamber view in 89 (100%) and in the lateral 4-chamber view in only 26 (29%; P = .001). CONCLUSIONS:Echogenic intracardiac foci are not easily seen in the lateral 4-chamber view. Studies that suggest an increased risk of aneuploidy when echogenic foci are seen should specify the orientation of the 4-chamber view used.

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.