PubMed Health⌕ Search

Biomedical subjects

Cande V Ananth

Publications and source records attributed to Cande V Ananth.

At least 55 records · Page 3Linked to original sources
PubMed2004

Analysis of neonatal mortality:is standardizing for relative birth weight biased?

BACKGROUND: Infant mortality has traditionally been analyzed as a function of birth weight and birth weight-specific mortality. Often, however, when comparing two populations, the population with higher overall mortality has lower mortality at low birth weights and a reversed pattern at higher birth weights. Methods standardizing birth weight, such as the "relative birth weight", have been proposed to eliminate these crossover effects, but such methods do not account for the separate contributions to birth weight of gestational age and fetal "growth." METHODS: Using data for singleton U.S. Blacks (n = 3,683,572) and Whites (n = 18,409,287), we compared neonatal mortality, gestational age, and the difference between the observed birth weight and the optimal birth weight (the weight at which neonatal mortality was lowest) among Black and White infants at the same relative birth weight. RESULTS: At relative birth weights below zero, gestational ages were, on average, 2.4 +/- 1.5 (mean +/- standard deviation) weeks shorter for Blacks than for Whites for the same relative birth weight. At relative birth weights above zero, no differences were observed in gestational age, but the optimal birth weight occurred at a much higher relative birth weight in Whites than in Blacks (4150 vs. 3550 g). CONCLUSIONS: Our results suggest that comparisons of neonatal mortality between groups using "relative" birth weight may be potentially biased by differences in gestational age at low birth weights, and by the distance from the optimal birth weight at higher birth weights.

Journal Article↗
PubMed2004

A parsimonious explanation for intersecting perinatal mortality curves: understanding the effects of race and of maternal smoking.

BACKGROUND: Neonatal mortality rates among black infants are lower than neonatal mortality rates among white infants at birth weights <3000 g, whereas white infants have a survival advantage at higher birth weights. This finding is also observed when birth weight-specific neonatal mortality rates are compared between infants of smokers and non-smokers. We provide a parsimonious explanation for this paradoxical phenomenon. METHODS: We used data on births in the United States in 1997 after excluding those with a birth weight <500 g or a gestational age <22 weeks. Birth weight- and gestational age-specific perinatal mortality rates were calculated per convention (using total live births at each birth weight/gestational age as the denominator) and also using the fetuses at risk of death at each gestational age. RESULTS: Perinatal mortality rates (calculated per convention) were lower among blacks than whites at lower birth weights and at preterm gestational ages, while blacks had higher mortality rates at higher birth weights and later gestational ages. With the fetuses-at-risk approach, mortality curves did not intersect; blacks had higher mortality rates at all gestational ages. Increases in birth rates and (especially) growth-restriction rates presaged gestational age-dependent increases in perinatal mortality. Similar findings were obtained in comparisons of smokers versus nonsmokers. CONCLUSIONS: Formulating perinatal risk based on the fetuses-at-risk approach solves the intersecting perinatal mortality curves paradox; blacks have higher perinatal mortality rates than whites and smokers have higher perinatal mortality rates than nonsmokers at all gestational ages and birth weights.

Journal Article↗
PubMed2004

Trends in twin neonatal mortality rates in the United States, 1989 through 1999: influence of birth registration and obstetric intervention.

OBJECTIVE: We sought to evaluate the contributions of changes in birth registration, labor induction, and cesarean delivery on trends in twin neonatal mortality rates. STUDY DESIGN: We conducted a population-based, retrospective cohort study of twin live births, using linked birth-infant death data in the United States (1989-1999). Relative risks and 95% confidence intervals that quantified changes in neonatal (0-27 days) mortality rates were derived from ecologic logistic regression models that were fit after aggregation of the data by each state in the United States. RESULTS: The frequency of live born twins who weighed <500 g increased 72%, from 0.7% in 1989 to 1.2% in 1999, of live born twins who weighed 500 to 749 g and 750 to 999 g increased by 55% and 28%, respectively, between 1989 and 1999. Preterm birth rates increased by 19%, from 46.2% in 1989 to 57.2% in 1999. The rate of labor induction increased from 5.8% to 13.9%, and the cesarean delivery rate increased from 49.8% to 56.3%. Between 1989 to 1991 and 1997 to 1999, the crude neonatal mortality rates among twins who weighed >or=500 g declined by 37% (95% CI, 35%-40%) from 21.5 to 13.6 per 1000 twin live births. Adjustments for preterm labor induction, preterm cesarean delivery, term labor induction, term cesarean delivery, and sociodemographic factors had little influence on neonatal mortality rate trends. CONCLUSION: Increases in preterm birth because of obstetric intervention among twins have not led to increases in twin neonatal mortality rates in the United States.

Cause of Death↗
PubMed2004

Fetal transcerebellar diameter measurement with particular emphasis in the third trimester: a reliable predictor of gestational age.

OBJECTIVE: The purpose of this study was to validate prospectively a previous retrospectively established nomogram for the prediction of gestational age using transcerebellar diameter, especially in the third trimester. STUDY DESIGN: In a previous study, we retrospectively constructed a cross-sectional nomogram using transcerebellar diameter measurements in 24,026 well-dated singleton fetuses. In the present study, this nomogram was validated prospectively on the basis of patients who were seen between August 2002 and May 2003 and who were carrying non-anomalous and non-malformed singleton gestations between 14 and 42 weeks (n = 2597 gestations). The actual gestational age was then subtracted from the predicted gestational age, and the concordance between actual and predicted gestational ages was assessed based on the Pearson correlation (r). RESULTS: Concordance between the actual and predicted gestational age was high (r = 0.92; P < .0001). This agreement was superior in the second trimester (r = 0.93; P < .0001) than in the third trimester (r = 0.81; P < .001). Between 17 and 21 weeks, and between 22 and 28 weeks of gestation, the predicted gestational age ranged between 0 and 4 days, and between 0 and 2 days, respectively, of actual gestational age. Between 29 and 36 weeks of gestation, predicted gestational age was within 5 days of actual gestational age; at 37 weeks of gestation, the predicted gestational age was discrepant by 9 days. CONCLUSION: This prospective study demonstrates that transcerebellar diameter measurement is an accurate predictor of gestational age, even in the third trimester of pregnancy.

Cerebellum↗
PubMed2004

Estimation of cumulative odds ratios.

PURPOSE: Standard estimation of ordered odds ratios requires the constraint that the etiologic effects of exposure are homogenous across thresholds of the ordered response. We present a method to relax this often-unrealistic constraint. METHODS: The kernel of the proposed method is the expansion of observed data into "person-thresholds." Using standard statistical software, for each subject we create a separate record for each response threshold and then apply binary logistic regression to estimate generalized cumulative odds ratios for one or more exposures. RESULTS: Two examples demonstrate that the proposed method provides increased flexibility in assessing the etiologic effects of exposures. A Monte Carlo simulation study supports the proposed approach by suggesting the estimated cumulative odds ratios are unbiased with proper confidence interval coverage attained by use of generalized estimating equations. CONCLUSION: The proposed method provides simple estimates of ordered odds ratios that allow the etiologic effects of exposure to vary across levels of the ordered response.

Diabetic Retinopathy↗
PubMed2004

Perinatal mortality in first- and second-born twins in the United States.

OBJECTIVE: To evaluate the prevailing mortality paradox that second-born twins are at higher risk of perinatal mortality than first-born twins. METHODS: We used the 1995-1997 United States "matched multiple birth" data files assembled by the National Center for Health Statistics, for analysis of risk of perinatal mortality in first- and second-born twins (293788 fetuses). Perinatal mortality was defined to include stillbirths after 20 weeks of gestation and neonatal deaths (deaths within the first 28 days). Gestational age-specific risk of perinatal mortality (per 1000 total births), stillbirth (per 1000 total births), and neonatal mortality (per 1000 livebirths) by order of twin birth were based on the fetuses-at-risk approach. Associations between order of birth and mortality indices were evaluated by fitting multivariable logistic regression models based on the method of generalized estimating equations. These models were adjusted for several potential confounding factors. RESULTS: Perinatal mortality was 37% higher in second-born (26.1 per 1000 total births) than in first-born (20.3 per 1000 total births) twins (adjusted relative risk [RR] 1.37; 95% confidence interval [CI] 1.32, 1.42). The increased risk of perinatal mortality in second-born twins was chiefly driven by a 2.46-fold (95% CI 2.29, 2.63) increase in the number of stillbirths. However, the risk of neonatal mortality was very similar between first- and second-born twins (RR 0.99, 95% CI 0.95, 1.04). CONCLUSIONS: The increased risk of perinatal death in second-born twins is driven chiefly by increased rates of stillborn second twins. Thus, the increased mortality in second-born over first-born twins probably is an artifact of mortality comparisons.

Adult↗
PubMed2004

Preterm premature rupture of membranes, intrauterine infection, and oligohydramnios: risk factors for placental abruption.

OBJECTIVE: To examine whether preterm premature rupture of membranes (PROM), intrauterine infection, and oligohydramnios are risk factors for placental abruption. METHODS: Data for this retrospective cohort study were derived from the 1988 National Maternal and Infant Health Survey (N = 11,777). Association between abruption and these clinical risk factors was expressed as relative risk (RR) and 95% confidence interval (CI), with multivariate adjustment for potential confounders. RESULTS: The overall incidence of abruption was 0.87%. The risk of abruption was 3.58-fold higher (95% CI 1.74-7.39) among women with preterm PROM (2.29%) compared with women with intact membranes (0.86%). The rates of abruption among women with and without intrauterine infection were 4.81% and 0.83%, respectively (RR 9.71, 95% CI 3.23-29.17). However, oligohydramnios was not associated with abruption (1.46% compared with 0.87%; RR 2.09, 95% CI 0.92-5.31). Compared with women with intact membranes, the RR for abruption among preterm PROM and whose membranes were ruptured for 24-47 hours and 48 hours or more before delivery, respectively, were 2.37 (95% CI 0.99-9.09), and 9.87 (95% CI 3.57-27.82). When preterm PROM was accompanied by intrauterine infections, the RR for abruption was 9.03 (95% CI 2.80-29.15) compared with women with intact membranes and no infections. Similarly, preterm PROM accompanied by oligohydramnios conferred over a 7.17-fold risk (95% CI 1.35-38.10) for abruption compared with women with neither of these 2 conditions. CONCLUSION: Women presenting with preterm PROM are at increased risk of developing abruption, with the risk being higher either in the presence of intrauterine infections or oligohydramnios. Physicians managing patients with preterm PROM should be aware that these patients are at increased risk of developing abruption after 24 hours following preterm PROM.

Abruptio Placentae↗
PubMed2004

Twin deliveries in the United States over three decades: an age-period-cohort analysis.

OBJECTIVE: Time is an important variable in understanding the recent increase in twin deliveries in the United States. Therefore, this study was designed to estimate the influences of maternal age, period (year) of delivery, and maternal-birth-year cohort on trends in rates of twin deliveries. METHODS: United States natality data were used to assess trends in twin pregnancies resulting in live births. This age-period-cohort analysis included 7, 5-year maternal-age groups (15-19 through 45-49 years), 6 twin delivery periods (1975, 1980, 1985, 1990, 1995, and 2000), and 12, 5-year maternal birth cohorts (1926-1930 through 1981-1985). The independent effects of maternal age, twin delivery period, and maternal birth cohort on twin delivery rates for blacks and whites were modeled using Poisson regression techniques. RESULTS: Our study assessed 95,042 blacks and 401,989 whites with twin deliveries. Twin deliveries increased by 46% for blacks and 62% for whites from 1975 to 2000, with the largest increase occurring in the year 2000. For blacks, maternal age had the strongest impact on the increasing twin delivery rates, followed by period of delivery. For whites, the greatest effect was due to period of delivery, followed by maternal birth year cohort and, lastly, maternal age. CONCLUSION: Our data confirm the importance of nature's biologic contribution of maternal aging to twin delivery rates, but suggest that recent changes in the environment surrounding pregnancy (nurture) also influence twin delivery rates. The relative contributions of biologic versus environmental influences appear to differ among blacks and whites.

Adolescent↗
PubMed2004

Noninvasive ultrasound assessment of maternal vascular reactivity during pregnancy: a longitudinal study.

OBJECTIVE: To estimate the pattern of maternal vascular reactivity in normal and high-risk pregnancies using postocclusion brachial artery diameter. METHODS: Prospective, longitudinal study of 44 low-risk singleton pregnancies and 28 high-risk pregnancies, defined as pregestational diabetes (n = 7), chronic hypertension (n = 4), twin gestation (n = 6), and a previous history of preeclampsia, fetal growth restriction, or vascular disease (n = 11). During each trimester, the brachial artery was ultrasonographically imaged above the antecubital crease. Brachial artery diameter was measured and then occluded for 5 minutes using an inflated blood pressure cuff. Changes in brachial artery diameter at 1 minute after occlusion were expressed as percent change from baseline and were compared across trimesters for both low-risk and high-risk groups, adjusting for potential confounders. RESULTS: Brachial artery diameters were increased after occlusion in every trimester for all groups. For low-risk women, the degree of postocclusion brachial artery dilatation was similar in the first and second trimesters, but was lower in the third trimester. In the first trimester, low-risk women had significantly greater brachial artery diameter increases at 1 minute compared with high-risk singleton pregnancies (19% compared with 12%; P <.001). Compared with low-risk women, pregnancies complicated by pregestational diabetes or chronic hypertension had significantly smaller 1-minute brachial artery diameter changes in the first trimester (7.0 +/- 0.5%, P <.001), whereas twin gestations had greater brachial artery responses (22.9 +/- 6.0%, P <.001). Women with previous preeclampsia or vascular disease had responses similar to low-risk women. CONCLUSION: Maternal vascular reactivity as assessed by postocclusion brachial artery dilatation decreases in the third trimester in both low-risk and high-risk women. In addition, singleton pregnancies at high risk for preeclampsia display decreased brachial artery reactivity compared with low-risk women.

Brachial Artery↗
PubMed2004

Small-for-gestational-age births in the United States: an age-period-cohort analysis.

BACKGROUND: During the last 2 decades, the rate of low birthweight has increased, as has the rate of preterm delivery, among both whites and blacks. Examination of causes for these secular trends has focused largely on changes in the distributions of maternal age and, less commonly, on birth cohort. Little is known as to how age, period, and birth cohort interact on trends in small births at term. METHODS: The U.S. natality files were used to assess trends in term (>/=37 weeks gestation) small-for-gestational age (SGA) births for 7 5-year maternal age groups (15-19 through 45-49 years), 6 delivery periods (1975, 1980, 1985, 1990, 1995, and 2000), and 12 5-year maternal birth cohorts (1926-1930 through 1981-1985). SGA births were defined as sex-specific birthweight below the 10th percentile for gestational age based on 1995 livebirths in the United States. Logistic regression models were fit to determine the independent effects of age, delivery period, and birth cohort on term SGA trends, separately for blacks and whites. RESULTS: Between 1975 and 2000, term SGA births declined by 23% (from 21% to 16%) among blacks and by 27% (from 12% to 9%) among whites. Term SGA births declined with increasing age up to 30-34 years, but increased among older women. Within strata of maternal age, the risk also declined with later maternal birth cohorts, among both blacks and whites. The strongest influence on SGA trends was from maternal age, followed by maternal birth cohort, and lastly by delivery period. In general, for any combination of age, period, and birth cohort, blacks showed 1.5- to 2-fold higher rates of term SGA than whites. CONCLUSIONS: The persistence of strong maternal age effects on risk of term SGA births suggests that the effect of age is at least partly the result of biologic factors. Term SGA trends were generally consistent for blacks and whites, although the magnitude of difference in the risks for combinations of age, period, or mother's birth cohort was higher among blacks than whites.

Adolescent↗
PubMed2003

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

BACKGROUND: Birth 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. METHODS: We 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. RESULTS: Conventional 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. CONCLUSIONS: The proper conceptualization of perinatal risk eliminates the mortality crossover paradox and provides new insights into perinatal health issues.

Journal Article↗
PubMed2003

Bacterial vaginosis, vaginal fluid neutrophil defensins, and preterm birth.

OBJECTIVE: To examine the association between bacterial vaginosis, vaginal fluid neutrophil defensins, and preterm birth. METHODS: Vaginal fluid specimens were obtained at 24-29 weeks' gestation from 242 cases with preterm birth and 507 noncases sampled using a case-cohort study design. We tested for bacterial vaginosis by Gram staining and Nugent scores and assayed for neutrophil defensins by enzyme-linked immunosorbent assay. Bacterial vaginosis was studied as a categoric variable (negative, intermediate, and positive), whereas defensins were studied as a continuous, categoric (based on percentiles), and dichotomous measure (presence versus absence). Three gestational age cut points were used to define preterm birth. Modified Cox proportional hazard models were used to evaluate the associations between bacterial vaginosis, defensins, and degree (less than 32, less than 34, and less than 37 weeks) and type (premature rupture of membranes, preterm labor) of preterm birth. RESULTS: Elevated vaginal fluid neutrophil defensins were not associated with birth before 37 weeks. Compared with women who did not have measurable vaginal fluid defensins, women with higher defensin levels (0-2.8 micro g/mL, 2.8-8.2 micro g/mL, and greater than 8.2 micro g/mL) had a greater risk of delivering before 32 weeks. Hazard ratios adjusted for maternal race and vaginal bleeding during pregnancy and 95% confidence intervals for these defensin levels were 1.7 (0.4, 6.9), 2.4 (0.7, 7.9), and 3.1 (1.0, 9.8), respectively. Bacterial vaginosis status did not influence the association between defensins and preterm birth. CONCLUSION: Elevated concentrations of vaginal fluid neutrophil defensins at 24-29 weeks' gestation might predict preterm birth before 32 weeks.

Adult↗
PubMed2003

Obstetric admissions to the intensive care unit: outcomes and severity of illness.

OBJECTIVE: To determine whether mortality prediction based on a current model of outcome prediction is accurate in obstetric patients. METHODS: Consecutive obstetric admissions to a medical intensive care unit from 1991 to 1998 were reviewed to determine whether mortality prediction is feasible in obstetric patients based on a widely used model. The Simplified Acute Physiologic Score (SAPS II) was used to predict the probability of hospital mortality. RESULTS: The Simplified Acute Physiologic Score overestimated mortality in all patients (19 predicted deaths, eight observed) but accurately predicted mortality in patients admitted to the intensive care unit for medical reasons (seven predicted, five observed). The Simplified Acute Physiologic Score did not predict mortality in patients admitted for obstetric indications or postpartum hemorrhage. Median SAPS II scores were significantly higher in those patients who died, compared with survivors. For all groups, SAPS II scores were correlated with intensive care unit length of stay but not hospital length of stay. CONCLUSION: The Simplified Acute Physiologic Score accurately predicts hospital mortality in obstetric patients admitted to the intensive care unit for medical reasons but not for indications related to pregnancy and delivery. An alternate model that predicts outcomes in obstetric patients admitted for obstetric indications should be developed.

Adult↗
PubMed2003

The clustering of neonatal deaths in triplet pregnancies: application of response conditional multivariate logistic regression models.

BACKGROUND/OBJECTIVES: A population-based retrospective cohort study of triplet pregnancies was conducted to estimate individual probabilities of neonatal mortality (death within 28 days of birth) conditional on the number of neonatal deaths experienced by other infants in the triplet set. METHODS: Data on 4,697 triplet sets (14,091 births) were derived from the U.S. 1995-1997 matched multiple birth file assembled by the National Center for Health Statistics. Response conditional multivariate logistic regression was used to model the association of neonatal mortality among cotriplets. To account for the correlation of the outcomes among cotriplets, regression parameters were estimated by the methodology of generalized estimating equations with robust variance estimates. RESULTS: Compared with a triplet where both cotriplets survived the neonatal period, the adjusted odds ratio and 95% confidence interval (CI) for a neonatal death associated with one and two cotriplet neonatal deaths were 1.80 (95% CI 1.06, 3.04), and 13.41 (95% CI 2.31, 77.7), respectively, after adjusting for birthweight and gestational age. CONCLUSIONS: These results show strong evidence of clustering of neonatal deaths in triplet pregnancies.

Humans↗
PubMed2003

Placenta previa in singleton and twin births in the United States, 1989 through 1998: a comparison of risk factor profiles and associated conditions.

OBJECTIVE: The purpose of this study was to compare risk factor profiles for placenta previa between singleton and twin live births. STUDY DESIGN: This cohort study was based on United States natality data files (1989 through 1998) and comprised 37,956,020 singleton births and 961,578 twin births. Women who were diagnosed with placenta previa were included only if they were delivered by cesarean delivery. Risk factors for placenta previa that were examined included sociodemographic (age, gravidity, education, marital status, and race), behavioral (prenatal care, smoking, and alcohol use), previous preterm birth, and medical and obstetric factors. Effect modification between maternal age and gravidity and the dose-response relationship with number of cigarettes smoked/day on placenta previa risk were also evaluated. RESULTS: The rate of placenta previa was 40% higher among twin births (3.9 per 1,000 live births, n = 3,793 births) than among singleton births (2.8 per 1,000 live births, n = 104,754 births). Comparison of risk factors for placenta previa between the singleton and twin births revealed fairly similar risk factor profiles. Compared with primigravid women <20 years old, the risk for placenta previa increased by advancing age and by increasing number of pregnancies among both singleton and twin births. The number of cigarettes smoked per day also showed a dose-response trend for placenta previa risk in the two groups. CONCLUSION: The increased rate of placenta previa among twin births underscores the need to monitor carefully such pregnancies with heightened suspicion and awareness for the development of this condition.

Adult↗
PubMed2003

Intrapartum fever at term: serum and histologic markers of inflammation.

OBJECTIVE: This study was undertaken to determine whether intrapartum fevers at term are associated with markers of acute inflammation in maternal, fetal, and placental compartments. STUDY DESIGN: Term cases with intrapartum fever (temperature >/=100.4 degrees F) were recruited with gestational age-matched controls. Maternal serum and umbilical vein blood were collected and assayed for interleukin-6 (IL-6) levels. Placentas were examined for histologic chorioamnionitis. Demographic and clinical data were collected and compared between cases and controls. RESULTS: Forty-seven case-control pairs were analyzed. Maternal IL-6 levels were higher in cases than in controls (median of 145 pg/mL vs 42 pg/mL, P <.0001). Umbilical vein IL-6 levels also were higher in cases than controls (median 9 pg/mL vs 3.5 pg/mL, P =.01), but more than half of levels in cases were below 11 pg/mL. Only 31.1% of febrile cases had moderate or severe histologic chorioamnionitis. Multivariable logistic regression identified maternal serum IL-6 levels, nulliparity, and number of vaginal examinations as the major predictors of intrapartum fever at term. CONCLUSION: The maternal inflammatory response as measured by maternal serum IL-6 levels is a strong marker for term intrapartum fever. The much weaker association of fetal and placental inflammatory responses suggest a smaller than expected contribution of intra-amniotic inflammation to term intrapartum fevers.

Adult↗
PubMed2003

Birth weight discordancy and adverse perinatal outcomes among twin gestations in the United States: the effect of placental abruption.

OBJECTIVE: We evaluated whether the relationship between birth weight discordancy of twins and stillbirth, neonatal deaths, and preterm births was modified by the presence of abruption. STUDY DESIGN: We used the 1995 to 1997 matched multiple birth file for United States twin births (n = 269287). Birth weight discordancy was defined as the ratio of the difference in birth weight of the heavier from the lighter twin to that of the heavier twin and was categorized as <5%, 5% to 9%, 10% to 14%, 15% to 19%, 20% to 29%, 30% to 39%, and >or=40%. We evaluated the risks of stillbirth (>or=20 weeks of gestation), neonatal deaths (within 28 days after birth), and preterm birth (< 32 weeks) in the presence and absence of abruption. Associations between birth weight discordancy and these perinatal outcomes were expressed as adjusted relative risks and were derived from multivariable logistic regression models, based on the method of generalized estimating equations. Risk of these outcomes were derived for each stratum of birth weight discordancy and abruption status, with the <5% birth weight discordancy, nonabruption status labeled as the reference group. All analyses were performed separately for same and different sex twins. RESULTS: A birth weight discordancy of >or=20% among same sex (adjusted relative risk, 1.2; 95% CI, 1.1, 1.4), and >or=40% among different sex twins (relative risk, 2.2; 95% CI, 1.7, 2.8) conferred increased risk for abruption. Among nonabruption births, a birth weight discordancy of >or=15% among same sex and >or=30% among different sex twins increased the risk of stillbirths, neonatal deaths, and preterm births. Among abruption births, however, the risks were increased even in the lowest birth weight discordancy category (<5%). The relative risks of stillbirths and neonatal deaths among abruption births were significantly higher for each birth weight discordancy group, both for same and different sex twins, compared with the reference group. The association between birth weight discordancy and preterm birth was not modified by either the presence or absence of abruption. CONCLUSION: Birth weight discordancy of >or=15% for same sex and >or=30% for different sex confer greatest risk of adverse perinatal outcomes in the absence of abruption. In the presence of placental abruption, these risks are further compounded. The results underscore the need for careful monitoring of twin pregnancies.

Abruptio Placentae↗