Kitaw Demissie

Fetal and neonatal mortality among twin gestations in the United States: the role of intrapair birth weight discordance

OBJECTIVE To examine the association of intrapair birth weight discordance with fetal and neonatal mortality. METHODS We used the United States (1995–1997) Matched Multiple Birth File (n = 297,155). RESULTS Among twin live births and stillborn fetuses, 29.9% had less than 5% birth weight discordance, 24.2% had 5–9%, 29.6% had 10–19%, 11.1% had 20–29%, 3.4% had 30–39%, and 1.8% had 40% or more. The stillborn fetus rate increased progressively with increasing birth weight discordance for smaller and larger twins of the same sex. Compared with the less than 5% birth weight discordance category, the adjusted odds ratios (OR) (95% confidence intervals [CIs]) for stillborn fetus associated with 5–9%, 10–19%, 20–29%, 30–39%, and 40% or more birth weight discordance, respectively, were 0.81 (95% CI 0.58, 1.11), 1.41 (95% CI 1.07, 1.84), 1.74 (95% CI 1.28, 2.35), 3.06 (95% CI 2.21, 4.24), and 4.29 (95% CI 3.05, 6.04) for smaller twins. The corresponding ORs (95% CIs) for larger twins were 0.78 (95% CI 0.57, 1.08), 1.26 (95% CI 0.96, 1.66), 1.77 (95% CI 1.27, 2.46), 3.38 (95% CI 2.33, 4.92), and 2.91 (95% CI 1.89, 4.47). Similar associations were observed among smaller but not larger twins of opposite sex. Among larger but not smaller twins of the same sex, increasing birth weight discordance was associated with overall neonatal deaths. This association was not apparent among smaller and larger twins of opposite sex. However, increasing birth weight discordance was associated with neonatal deaths related to congenital malformations among smaller and larger twins. CONCLUSION The results provide evidence that increased twin birth weight discordance was associated with increased risk of intrauterine death and malformation‐related neonatal deaths.

Adverse Outcomes in Pregnancies of Asthmatic Women: Results from a Canadian Population

PURPOSE There has been little attention paid to asthma complicating pregnancy. This study is among the few studies that investigated this issue in a large Canadian population (more than two millions of Canadian pregnant women). METHODS We carried out a historical cohort study using hospital discharge data collected by the Canadian Institute for Health Information for fiscal years 1989/90 to 1995/96. RESULTS A total 2,017,553 obstetric deliveries were included in the analysis. Overall prevalence of asthma among these Canadian women were 0.43%, yielding a total of 8672 cases of asthmatic mothers. Maternal asthma was associated with all of the adverse pregnancy outcomes examined (including fetal death, preterm labour, hypertensive disorders of pregnancy, gestational diabetes, antepartum hemorrhage, infection of the amniotic cavity, premature rupture of membrane, cesarean delivery, as well as postpartum hemorrhage), and adjustment for important confounding factors by multiple logistic regression analysis did not change the overall results. These associations were consistently observed in teenage and adult mothers, although the associations in teenage mothers tended to be stronger than in adult mothers. CONCLUSIONS This study confirms that pregnant women with asthma are at substantially increased risk for many adverse pregnancy outcomes. For this reason, pregnant women with asthma are a particularly high-risk group to which extra attention, including increased efforts at education, monitoring, and optimal asthma management, may be appropriate.

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.

Conducting Molecular Epidemiological Research in the Age of HIPAA: A Multi-Institutional Case-Control Study of Breast Cancer in African-American and European-American Women

Breast cancer in African-American (AA) women occurs at an earlier age than in European-American (EA) women and is more likely to have aggressive features associated with poorer prognosis, such as high-grade and negative estrogen receptor (ER) status. The mechanisms underlying these differences are unknown. To address this, we conducted a case-control study to evaluate risk factors for high-grade ER- disease in both AA and EA women. With the onset of the Health Insurance Portability and Accountability Act of 1996, creative measures were needed to adapt case ascertainment and contact procedures to this new environment of patient privacy. In this paper, we report on our approach to establishing a multicenter study of breast cancer in New York and New Jersey, provide preliminary distributions of demographic and pathologic characteristics among case and control participants by race, and contrast participation rates by approaches to case ascertainment, with discussion of strengths and weaknesses.

A parsimonious explanation for intersecting perinatal mortality curves: understanding the effect of plurality and of parity

BackgroundBirth weight- and gestational age-specific perinatal mortality curves intersect when compared across categories of maternal smoking, plurality, race and other factors. No simple explanation exists for this paradoxical observation.MethodsWe used data on all live births, stillbirths and infant deaths in Canada (1991–1997) to compare perinatal mortality rates among singleton and twin births, and among singleton births to nulliparous and parous women. Birth weight- and gestational age-specific perinatal mortality rates were first calculated by dividing the number of perinatal deaths at any given birth weight or gestational age by the number of total births at that birth weight or gestational age (conventional calculation). Gestational age-specific perinatal mortality rates were also calculated using the number of fetuses at risk of perinatal death at any given gestational age.ResultsConventional perinatal mortality rates among twin births were lower than those among singletons at lower birth weights and earlier gestation ages, while the reverse was true at higher birth weights and later gestational ages. When perinatal mortality rates were based on fetuses at risk, however, twin births had consistently higher mortality rates than singletons at all gestational ages. A similar pattern emerged in contrasts of gestational age-specific perinatal mortality among singleton births to nulliparous and parous women. Increases in gestational age-specific rates of growth-restriction with advancing gestational age presaged rising rates of gestational age-specific perinatal mortality in both contrasts.ConclusionsThe proper conceptualization of perinatal risk eliminates the mortality crossover paradox and provides new insights into perinatal health issues.

Association of Codon 16 and Codon 27 β2‐Adrenergic Receptor Gene Polymorphisms with Obesity: A Meta‐analysis

Objective: To search for an association between the Glu27Gln (rs1042714; B27) and the Arg16Gly (rs1042713; B16) polymorphisms of the β2‐adrenergic receptor (ADRB2) gene and obesity.

Occurrence and predictors of cesarean delivery for the second twin after vaginal delivery of the first twin.

OBJECTIVE: To estimate the occurrence and to assess clinical predictors of emergent cesarean delivery in the second twin after vaginal delivery of the first twin. METHODS: We conducted a population-based cohort study, using the 1995–1997 linked mother/infant twin data from the United States. The adjusted risk ratios and population attributable risks of clinical predictors of emergent cesarean delivery in second twins were estimated for the overall study sample and for those born at less than 36 or 36 weeks or more of gestation. RESULTS: Among the 61,845 second twin births with the first twin delivered vaginally, 5,842 (9.45%) were delivered by cesarean. The cesarean delivery rate was increased in infants born to mothers with medical or labor and delivery complications. Breech and other malpresentations were the most important predictors of emergent cesarean delivery for the second twin (population attributable risk 33.2%; 95% confidence interval 31.8%, 34.6%). Operative vaginal delivery of the first twin was associated with a decreased risk of cesarean delivery for the second twin. Prediction of emergent cesarean for the second twin by clinical factors was stronger in term births than preterm births. CONCLUSION: In the general population, the cesarean delivery rate for the second twin after vaginal delivery of the first twin is approximately 9.5%. With the presence of breech and other malpresentations, the need for emergent cesarean delivery of the second twin after vaginal delivery of the first twin is increased by 4-fold. LEVEL OF EVIDENCE: II-2

Impact of mode of delivery on neonatal complications: Trends between 1997 and 2005

Objective. This study examined whether rates of selected neonatal complications vary by mode of delivery and whether these rates are changing as a result of the increasing cesarean delivery rate. Method. Birth certificates in New Jersey from 1997 to 2005 were matched to hospital discharge records for mothers and newborns. Results. In New Jersey, the total cesarean section rate for 2005 was 35.3%, a relative increase of 46% since 1997 (from 24.2%). Rates of transient tachypnea of the newborn (TTN) and respiratory distress syndrome (RDS), regardless of mode of delivery, increased between 1997 and 2005 from 3.3 to 3.9% and 2.1 to 2.4%, respectively. Newborn injuries declined sharply (from 4.1 to 2.6%), whereas intra-ventricular hemorrhage (IVH) rates remained stable. The rates of RDS, TTN and IVH were highest for cesarean delivery without trial of labor, while the rate of injuries was highest for instrumental vaginal delivery. Conclusion. Neonatal complication rates varied by mode of delivery and decreased with gestational age.

Asthma Development with Obesity Exposure: Observations from the Cohort of the National Health and Nutrition Evaluation Survey Epidemiologic Follow-up Study (NHEFS)

Results of cross-sectional studies suggest an association between body mass index and asthma. However, it is not clear whether the occurrence of asthma precedes increased body mass index or vice versa. From 1971 to 1975, the First National Health and Nutrition Examination Survey collected height and weight data and information about doctor-diagnosed asthma from 14,407 subjects aged 25–74. In 1982 through 1985, information was again obtained on doctor-diagnosed asthma with a follow-up rate of 84.8%. We took this opportunity to examine the relationship between body mass index (BMI) and asthma in this cohort. Subjects with subnormal BMI and subjects admitting current or history of doctor-diagnosed asthma were excluded from the cohort. Mean follow-up was 10 years (range 6.7–13 years). Analyses were adjusted for race and gender. Logistic regression analysis was conducted with asthma as the dependent variable and BMI modeled as a categorical independent variable (BMI groups). At baseline and at follow-up, increasing BMI was associated with increased prevalence of asthma. During the observation interval, however, no increased incidence of asthma associated with increasing BMI was noted. In comparison with normal BMI, the relative risk (RR) for development of doctor-diagnosed asthma in elevated BMI was 1.0 (95% confidence interval 0.9–1.2), for markedly elevated BMI was 1.0 (0.8–1.3), and for severely elevated BMI was 1.1 (0.8–1.5). Race did not affect this relationship. African Americans had an increased risk of asthma, but the risk was unassociated with increasing BMI. Gender did not affect this relationship. The disease burden of asthma appeared in normal weight and slightly overweight women rather than obese and markedly obese women. These results suggest that asthma development may be a point on the trajectory of chronic obesity disease or asthma appears with obesity as a concurrent disorder.

Missing paternal demographics: A novel indicator for identifying high risk population of adverse pregnancy outcomes

BackgroundOne of every 6 United Status birth certificates contains no information on fathers. There might be important differences in the pregnancy outcomes between mothers with versus those without partner information. The object of this study was to assess whether and to what extent outcomes in pregnant women who did not have partner information differ from those who had.MethodsWe carried out a population-based retrospective cohort study based on the registry data in the United States for the period of 1995–1997, which was a matched multiple birth file (only twins were included in the current analysis). We divided the study subjects into three groups according to the availability of partner information: available, partly missing, and totally missing. We compared the distribution of maternal characteristics, maternal morbidity, labor and delivery complications, obstetric interventions, preterm birth, fetal growth restriction, low birth weight, congenital anomalies, fetal death, neonatal death, post-neonatal death, and neonatal morbidity among three study groups.ResultsThere were 304466 twins included in our study. Mothers whose partners information was partly missing and (especially) totally missing tended to be younger, of black race, unmarried, with less education, smoking cigarette during pregnancy, and with inadequate prenatal care. The rates of preterm birth, fetal growth restriction, low birth weight, Apgar score <7, fetal mortality, neonatal mortality, and post-neonatal mortality were significantly increased in mothers whose partners information was partly or (especially) totally missing.ConclusionsMothers whose partners information was partly and (especially) totally missing are at higher risk of adverse pregnant outcomes, and clinicians and public health workers should be alerted to this important social factor.