Faculty Bibliography

OBJECTIVE:This study was undertaken to determine the association, if any, between prenatal care and postneonatal death in the presence and absence of high-risk pregnancy conditions. STUDY DESIGN/METHODS:Data were derived from the national linked birth/infant death data set for the years 1995 to 1997 provided by the National Center for Health Statistics. Analyses were restricted to singleton live births that occurred after 23 completed weeks of gestation. Multiple births, congenital malformations, chromosomal abnormalities, missing data on gestational age, and birth weight less than 500 g were excluded. Multivariable logistic regression analyses were used to adjust for various antenatal high-risk conditions, maternal age, gravidity, gestational age at delivery, birth weight, maternal education, marital status, smoking, and alcohol use. Postneonatal death rate was defined as the number of deaths between 28 and 365 days of life per 1,000 neonatal survivors. RESULTS:For 10,512,269 singleton live births analyzed, 21,962 (2.1 per 1,000) resulted in postneonatal death. Postneonatal death rates were higher for African American women than white women in the presence (3.8 vs 1.7 per 1,000) and absence (11.2 vs 5.3 per 1,000) of prenatal care. Lack of prenatal care was associated with increased relative risk (RR) for postneonatal death, 1.8-fold in African American women and 1.6-fold in white women. Lack of prenatal care was associated with increased postneonatal death rates to a similar degree for the individual high-risk pregnancy conditions for both African American and white women. Lack of prenatal care was associated with increased postneonatal death rates, especially in the presence of postterm pregnancy (RR 2.3, 95% CI 1.6, 3.1), pregnancy-induced hypertension (RR 2.2, 95% CI 1.5, 3.4), intrapartum fever (RR 2.1, 95% CI 1.2, 3.5), and small-for-gestational-age infant (RR 1.6, 95% CI 1.3, 2.0). CONCLUSION/CONCLUSIONS:Lack of prenatal care should be considered as a high-risk factor for postneonatal death for both African American and white women, especially if the pregnancy has been complicated by postdates, pregnancy-induced hypertension, intrapartum fever or small-for-gestational-age infant.

OBJECTIVE:The purpose of this study was to determine the incidence of trisomy 18 in women who are <35 years old and who have sonographically detected isolated choroid plexus cyst. STUDY DESIGN/METHODS:A meta-analysis of prospective trials that were published in the English language between 1990 and 2000 was performed. Each trial met the following inclusion criteria: (1) prospective trial, (2) total population screened during the study period reported, (3) maternal age (either numeric or descriptive) reported, and (4) pregnancy/neonatal outcomes reported. An isolated choroid plexus cyst for the purpose of this study was defined as absence of sonographically detected structural abnormalities and normal serum analyte screens, if reported. RESULTS:Eight trials met the criteria and were used for analysis. A total of 106,732 women were screened through articles that were published between 1990 and 2000. The total number of fetuses with choroid plexus cysts that were identified in second-trimester scans were 1,235 (incidence, 1.2%). The incidence of isolated choroid plexus cysts in women who were <35 years old was 1.0% (n = 1,017 women). There were no cases of trisomy 18 in women with isolated choroid plexus cyst who were <35 years old. Four structural abnormalities were noted on postnatal examination; all four neonates had normal karyotypes. CONCLUSION/CONCLUSIONS:There is no evidence that detection of isolated choroid plexus cyst in women who are <35 years of age increases the risk of trisomy 18. Therefore, amniocentesis is not warranted because of the inherent risk of pregnancy loss that is associated with the procedure. Better algorithms are needed to screen women who have a low risk for trisomy 18.

OBJECTIVE:Our purpose was to evaluate the association between birth weight (BW) and fetal death (FD) among pregnant nondiabetic and diabetic patients. STUDY DESIGN/METHODS:This was a retrospective cohort study using data for singleton births delivered between 1995 and 1997 in the United States (n = 10, 733, 983). Analysis was restricted to births that occurred at > or =20 completed weeks. FD rates among nondiabetic and diabetic patients (n = 271, 691) were determined for different 250-g BW categories. Adjusted relative risk (RR) and 95% CI for FD among diabetic compared with nondiabetic patients were derived through multivariable logistic regression models after potential confounders were controlled. RESULTS:Overall FD rates for nondiabetic and diabetic patients were 4.0 and 5.9 per 1,000 births, respectively, with adjusted RR of 2.0 (95% CI 1.8-2.2). Maternal diabetes was associated with increased FD rate for all BW categories after 1250 g. CONCLUSION/CONCLUSIONS:The FD rate is increased when birth weight is > or =4250 g in nondiabetic patients and > or =4000 g in diabetic patients.

This study was undertaken to examine the relationship between paternal and maternal age differences and adverse perinatal outcomes in the United States. Data were obtained on singleton pregnancies delivering at >or=20 weeks gestation in the United States in 1995-97 from the National Center for Health Statistics data sets. Adverse perinatal outcomes that were evaluated included fetal death rate (>or=20 weeks), preterm delivery <37 weeks and small-for-gestational-age (SGA) births (birthweight <10th centile for gestational age and corrected for sex). Age difference was defined as paternal minus maternal age. The analysis included 8995274 pregnancies (11.3% blacks, 88.7% whites). An increase in fetal death rate, preterm delivery and SGA births was noted among white women who were older than their male partners. For black mothers older than their partners, there was an increase in fetal death rate when the women were <20 years old, but a decrease in fetal death rate when >35 years old. Neither rates of preterm delivery nor SGA births were increased much for black women with varying parental age differences. This demonstrates that race and maternal age both contribute to the effects of parental age difference on adverse perinatal outcomes.

OBJECTIVE:To determine whether the presence of labor affects infant mortality among small-for-gestational-age (SGA) infants. METHODS:Data were derived from the United States national linked birth/infant death data sets for 1995-97. Singleton SGA live births in cephalic presentation delivered at 24-42 weeks' gestation were included. Mortality rates for SGA infants exposed and unexposed to labor were compared, and relative risks (RR) were derived using multivariable logistic regression models, after adjusting for potential confounding factors. RESULTS:Of 986 405 SGA infants, 87.4% were exposed to labor. Infants exposed to labor at 24-31 weeks had greater risks of dying during the early neonatal period (RR 1.79-1.86). Decreased risks of late and postneonatal death were observed at all gestational ages in the presence of labor. CONCLUSIONS:Exposure to labor is associated with an increased risk of early neonatal death among SGA infants, especially at gestational ages below 32 weeks. Future randomized trials are warranted to determine the optimal obstetric management of these high-risk infants.

OBJECTIVE: To estimate the value of second-trimester genetic sonography in detecting fetal Down syndrome in patients with advanced maternal age (at least 35 years) and normal triple screen. METHODS: Since July 1999, a prospective collection and recording of all individual triple screen risks for fetal Down syndrome was initiated for all patients with advanced maternal age presenting in our ultrasound unit for second-trimester genetic sonography. Genetic sonography evaluated the presence or absence of multiple aneuploidy markers. Outcome information included the results of genetic amniocentesis, if performed, and the results of pediatric assessment and follow-up after birth. RESULTS: By June 2001, 959 patients with advanced maternal age and normal triple screen were identified. Outcome information was obtained in 768 patients. The median risk for fetal Down syndrome based on maternal age was 1:213 (range 1:37-1:274). The median risk for fetal Down syndrome based on triple screen results was 1:1069 (range 1:275-1:40,000). A total of 673 patients had normal genetic sonography, and none (0%) had Down syndrome; 95 had one or more aneuploidy markers present, and four (4.2%) had fetuses with Down syndrome. The triple screen risks for these four fetuses ranged from 1:319 to 1:833. CONCLUSION: This study suggests that patients with advanced maternal age and normal genetic sonography carried very little risk for Down syndrome. The use of genetic sonography may increase the detection rate of fetal Down syndrome in this group of pregnant women

As genetic research and technology continues to expand, carrier testing for an increasing number of single gene disorders is becoming available. Tay-Sachs disease and cystic fibrosis are two common recessive conditions with large-scale health implications. Tay-Sachs disease was the first genetic disorder for which community-based screening efforts were utilized and has provided a foundation for the development of other screening programs. Cystic fibrosis testing, on the other hand, has additional complexities and the implementation of population-based screening has been under debate. The many issues (technical, educational, social, psychological and economical) which must be considered as preconceptional and prenatal genetic screening is incorporated into clinical practice are discussed here in the context of Tay-Sachs disease and cystic fibrosis.

OBJECTIVE: To determine the sensitivity of using a complete anatomic sonographic survey in detecting fetal abnormalities via correlation with perinatal autopsy results. METHODS: All perinatal autopsies (1994-2001) with positive findings for at least 1 fetal abnormality and performed by a single perinatal pathologist at our institution were retrospectively reviewed. From these cases, singleton fetuses who received prenatal sonography solely in our unit were identified. The sensitivity of sonography in detecting anomalous fetuses as well as fetal abnormalities and abnormalities by organ system was determined. Abnormalities were classified as major or minor In addition, findings from sonography and autopsy were compared, and their correlation was assigned to 1 of 3 categories. RESULTS: Of 88 fetuses identified, 85 had 1 or more abnormal structural sonographic findings (sensitivity for fetuses with anomalies, 97%). A total of 372 separate abnormalities were found on autopsy; of the 299 major and 73 minor abnormalities, prenatal sonography showed 224 (75%) and 13 (18%), respectively. There was either complete agreement or only minor differences between sonographic and autopsy findings in 57 (65%) of 88. The sensitivity of sonography in identifying abnormalities was greater than 70% in these systems: central nervous system, cardiac system, urinary system, extremities, genitalia, ribs, and hydrops. CONCLUSIONS: In experienced hands, sonography has 97% sensitivity in detecting anomalous fetuses when compared with perinatal autopsy results. Although the sensitivity of sonography in detecting major fetal abnormalities is 75%, the sensitivity for minor abnormalities is poor, even when using a complete anatomic sonographic survey. Although it has limitations, this type of survey is invaluable for both patients and physicians in diagnosing fetal abnormalities

OBJECTIVE:The purpose of this study was to determine the association between prenatal care in the United States and the neonatal death rate in the presence and absence of antenatal high-risk conditions. STUDY DESIGN/METHODS:Data were derived from the national perinatal mortality data sets for the years 1995 through 1997, which were provided by the National Center for Health Statistics. Analyses were restricted to singleton live births that occurred after 23 completed weeks of gestation. Multivariable logistic regression analyses were used to adjust for the presence or absence of various antenatal high-risk conditions, maternal age, gestational age at delivery, and birth weight. RESULTS:Of 10,530,608 singleton live births, 18,339 (1.7/1000 births) resulted in neonatal death. Neonatal death rates (per 1000 live births) were higher for African American infants compared with white infants in the presence (2.7 vs 1.5, respectively) and absence (10.7 vs 7.9, respectively) of prenatal care. Lack of prenatal care was associated with an increase in neonatal deaths, which was greater for infants born at > or =36 weeks of gestation (relative risk, 2.1; 95% CI, 1.8, 2.4). Lack of prenatal care was also associated with increased neonatal death rates in the presence of preterm premature rupture of the membranes (relative risk, 1.3; 95% CI, 1.1, 1.5), placenta previa (relative risk, 1.9; 95% CI, 1.2, 2.9), fetal growth restriction (relative risk, 1.7; 95% CI, 1.2, 1.6), and postterm pregnancy (relative risk, 1.4; 95% CI, 1.0, 2.9). CONCLUSION/CONCLUSIONS:In the United States, prenatal care is associated with fewer neonatal deaths in black and white infants. This beneficial effect was more pronounced for births that occurred at > or =36 weeks of gestation and in the presence of preterm premature rupture of the membranes, placenta previa, fetal growth restriction, and postterm pregnancy.

OBJECTIVE: To evaluate whether abnormal umbilical cord insertion (UCI) into the placenta is a risk factor for birth weight discordancy in twin gestations.METHODS: Pathology records of all liveborn twins delivered between January 1993 and June 1996 were reviewed. The information collected included gestational age at delivery, birth weight, gross placental pathology, and placental UCI-velamentous, marginal, or disc. Discordancy in birth weight was defined as an intrapair difference of at least 20%. Analyses were stratified on placental chorionicity. Odds ratios and 95% confidence intervals for birth weight discordancy were calculated based on the presence of an abnormal (velamentous or marginal) placental UCI relative to normal (disc) UCI on both placentae, after adjusting for potential confounders. RESULTS: There were 447 twin pairs identified. Dichorionic diamniotic placentation was present in 358 pairs (80.1%), monochorionic diamniotic in 84 (18.8%), and monochorionic monoamniotic in five (1.1%). There was a 13-fold increase in the risk of birth weight discordancy in monochorionic diamniotic twins in the presence of a velamentous UCI (odds ratio 13.5, 95% confidence interval 1.4, 138.4), with a rate of birth weight discordancy of 46%. This relationship was not demonstrated in dichorionic diamniotic twins (odds ratio 1.0, 95% confidence interval 0.3, 3.5). CONCLUSION: Birth weight discordancy in twins is a different entity depending on chorionicity. The substantial increase in birth weight discordancy in monochorionic diamniotic twins that accompanies velamentous UCI underscores the need for prenatal detection and increased surveillance in these twins