Birth weight trends among interracial black and white infants

I examined time trends in low birth weight (LBW) and very low birth weight (VLBW) among interracial compared with single-race infants. Using natality data from 1978 through 1997 for singleton births to black and white parents, I calculated relative risks (RRs) of LBW and VLBW for interracial compared with single-race births, stratified by maternal race and adjusted for maternal characteristics. Among black mothers, interracial births had lower risks of LBW and VLBW than single-race births, and RRs were similar throughout the time period [for example, adjusted RR = 0.76 and 95% confidence interval (CI) = 0.73-0.80 for LBW in 1994-1997]. Among white mothers, interracial infants had higher risks of LBW than single-race infants; however, the adjusted RRs declined over the time period, from 1.22 (95% CI = 1.19-1.27) in 1978-1981 to 1.05 (95% CI = 1.03-1.08) in 1994-1997. Since 1978, there has been some relative improvement in birth outcomes for infants of white mothers and black fathers compared with single-race white births. There was, however, no relative improvement for black mother/black father infants relative to black mother/white father births.     

Racial variation in spontaneous fetal deaths at 20 weeks or older in upstate New York, 1980-86.

The distribution of spontaneous fetal deaths (at age 20 weeks or more) by maternal race has received considerably less study than other adverse pregnancy outcomes. The purpose of this study was twofold--(a) to describe spontaneous fetal deaths among white, black, and American Indian women and (b) to determine if there was any variation by International Classification of Diseases, Ninth Revision (ICD-9) cause of death, gestational age at death, or maternal age at loss among these groups of mothers. Using the fetal death certificate registry maintained by the New York State Department of Health, 8,592 spontaneous fetal deaths at age 20 weeks or more were identified among upstate (exclusive of New York City) mothers between 1980 and 1986. By race it was 7,300 for white women, 1,257 for black women, and 27 for American Indian women. Spontaneous fetal death rates varied by maternal race as listed on vital records--black, 13.5 per 1,000 total births, white, 8.3, and American Indian, 8.1. The three leading causes of death (ICD-9,779, 762, and 761) did not vary by maternal race. Gestational age at death, imputed from last menstrual period, did vary by maternal race. Fetal deaths to white and black mothers were observed to occur most often between 24 weeks of pregnancy (39 percent) and 32 weeks (43 percent), while American Indian fetal deaths generally occurred later (more than 33 weeks) in pregnancy (41 percent). Most spontaneous fetal deaths occurred to mothers ages 20-29 regardless of race.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prenatal care and infant birth outcomes among Medicaid recipients

Infant morbidity due to low birth weight and preterm births results in emotional suffering and significant direct and indirect costs. African American infants continue to have worse birth outcomes than white infants. This study examines relationships between newborn hospital costs, maternal risk factors, and prenatal care in Medicaid recipients in an impoverished rural county in South Carolina. Medicaid African American mothers gave birth to fewer preterm infants than did non-Medicaid African American mothers. No differences in the rates of preterm infants were noted between white and African American mothers in the Medicaid group. Access to Medicaid services may have contributed to this reduction in disparities due to race. Early initiation of prenatal care compared with later initiation did not improve birth outcomes. Infants born to mothers who initiated prenatal care early had increased morbidity with increased utilization of hospital services, suggesting that high-risk mothers are entering prenatal care earlier.     

Reduced risk of low weight births among indigent women receiving care from nurse-midwives

STUDY OBJECTIVE: To examine the effect of a comprehensive prenatal and delivery programme administered by nurse-midwives on the risk of low weight births among indigent women. STUDY DESIGN: Historical prospective study. Birth outcomes among the cohort were compared with all county births during the same period, adjusting for maternal age and race. Results are expressed as relative risks with 95% confidence intervals. SETTING: An enhanced Medicaid funded pre-natal programme administered by nurse-midwives from 1992 to 1994 in Westchester County, New York. PARTICIPANTS: Indigent mothers (n = 1443), between the ages of 15 and 44, who were residents of Westchester County and indicated having Medicaid or no health care coverage. RESULTS: There were 1474 live births among cohort mothers. Mean (SD) gestational age was 39.4 (1.9) weeks. Less than 6% of births occurred before 37 weeks gestation. The mean birth weight of cohort infants was 3365.6 (518.6) g. Only 4.1% of the cohort births were less than 2500 g. Compared with all county births, the cohort showed a 41% reduction in the risk of low weight births (RRlbw = 0.59, 95% CI: 0.46 to 0.73, p < .001) and a 56% reduction when compared with county Medicaid births only (RR = 0.44, 95% CI: 0.34 to 0.57, p < .005) adjusting for maternal age and race. Larger reductions were found for very low weight births. CONCLUSIONS: Mothers need not be considered at high risk for adverse pregnancy outcomes based on their socioeconomic status alone. Moreover, a comprehensive prenatal programme administered by nurse-midwives may promote a reduction in adverse pregnancy outcomes among indigent mothers.     

The epidemiology of extrahepatic biliary atresia in New York State, 1983-98

The aetiology of biliary atresia, the leading cause of neonatal extrahepatic jaundice and the main indication for liver transplantation in children, is unknown. Recent research has focused on an infectious aetiology and the development of viral models in animals. The few published epidemiological studies report conflicting results for seasonal, geographical, and racial variations in incidence. In this study, New York State (NYS) Congenital Malformations Registry data from 1983 to 1998 were compared with resident live birth certificate data. County of residence, birth date, gestational age, birthweight, gender, maternal race and maternal age were extracted from the birth certificate data. Isolated and sequence cases were combined for analysis. Observed and expected numbers of cases were calculated by NYS region. Overall, 369 biliary atresia cases were reported in the 16-year study period, a rate of 0.85 [95% CI 0.76, 0.93] per 10,000 live births. Of these, 249 isolated/sequence cases were ascertained, a rate of 0.57 [95% CI 0.50, 0.64] per 10,000 live births. The rate ratio of biliary atresia in New York City (NYC) compared with other NYS was 2.19 [95% CI 1.69, 2.84]. Seasonal patterns varied by region with spring births at highest risk in NYC and September to November births at highest risk in other NYS. The rate ratio in black vs. white mothers was 1.94 [95% CI 1.48, 2.54]. Birthweight and gestational age were associated with biliary atresia with preterm low-birthweight infants at highest risk [RR 3.24, 95% CI 2.20, 4.76]. The association of isolated/sequence biliary atresia with season, preterm birth, and low birthweight in our study supports an infectious disease hypothesis.     

Trends in the sex ratio of California births, 1960-1996

STUDY OBJECTIVE: The male sex ratio at birth (or the proportion of male births in a population) has been suggested as a sentinel environmental health indicator. Usually around 51%, the proportion may be dramatically decreased in offspring of persons with chemical exposures. Recent publications from the USA and elsewhere have noted a small but apparently declining male birth proportion, suggesting the effect of some environmental exposures. This paper sought to examine these trends more closely in California's large and diverse population. DESIGN: Using computerised birth certificate data, time trends were examined by multivariate linear and spline regression, controlling for demographic factors. SETTING: California. PARTICIPANTS: About 15 million births from 1960 to 1996. MAIN RESULTS: In the raw data, the male birth proportion is indeed declining. However, during this period, there were also shifts in demographics that influence the sex ratio. Controlling for birth order, parents' age, and race/ethnicity, different trends emerged. White births (which account for over 80%) continued to show a statistically significant decline, while other racial groups showed non-statistically significant declines (Japanese, Native American, other), little or no change (black), or an increase (Chinese). Finally, when the white births were divided into Hispanic and non-Hispanic (possible since 1982), it was found that both white subgroups suggest an increase in male births. CONCLUSION: This analysis shows that the decline in male births in California is largely attributable to changes in demographics.     

Variations in pregnancy outcomes by race among 10-14-year-old mothers in the United States.

This study used the 1983-86 U.S. Linked Live Birth-Infant Death Files to examine variations in pregnancy outcomes among 38,551 U.S. resident black and white adolescents ages 10 through 14. The birth rate was 4.29 per 1,000 for blacks, more than 7 times the rate for whites (.59 per 1,000). Black mothers had higher proportions of very low and low birth weight infants than did whites (very low birth weight: 3.7 versus 2.6; low birth weight: 15.0 versus 10.5). Neonatal and infant mortality rates were higher among very low birth weight and low birth weight white infants. Neonatal and infant mortality rates were similar for normal birth weight infants of both races, but were 3.7 to 7.4 times higher among black infants with birth weights more than 4,250 grams. Logistic regression indicated that black mothers were at higher risk for having infants who were low birth weight, very low birth weight, small for gestational age, preterm, and very preterm. There were no differences by race for neonatal, postneonatal, and infant mortality. While the risk for poor pregnancy outcomes is great among young adolescents, young black adolescents appear to be particularly vulnerable. Attempts to reduce unintended pregnancies in this group should receive highest priority.     

A case-control study of hypocalcemia in high-risk neonates: racial, but no seasonal differences

A role for vitamin D in the defense against falling serum calcium (Ca) concentrations following cord clamping has been suggested. Since race and season are known to affect vitamin D status, we theorized that black race and birth in winter are additional risk factors for neonatal hypocalcemia (NHC). We retrospectively studied 13,462 infants born at University Hospital (Cincinnati, OH) between January 1, 1984 and December 31, 1987. Serum Ca was measured at 24 hours of age routinely in infants with low birth weight (less than 2500 g), preterm delivery (less than 2500 g), preterm delivery (less than 37 weeks), neonatal asphyxia, and diabetic mothers. After exclusion of infants of diabetic mothers (to remove maternal diabetes as a major confounder) and infants with major congenital anomalies, 714 infants remained. In multiple regression analysis, low serum Ca values were significantly associated with low gestational age (p less than 0.01), low Apgar score (p less than 0.01), and white race (p less than 0.01) (R2 = 0.457). Season or month of birth was not significant. In pair-matched analysis controlling for factors other than season, season of birth did not affect serum Ca. In pair-matched analysis controlling for factors other than race, white race was once again a risk factor for hypocalcemia. Thus, low gestational age, low Apgar score, and white race, but not black race and delivery in winter, are risk factors for NHC. We speculate that in our climate and with the prevailing diet in pregnancy, vitamin D deficiency does not appear to play a role in NHC.(ABSTRACT TRUNCATED AT 250 WORDS)     

A case-control study of hypocalcemia in high-risk neonates: racial,but no seasonal differences.

A role for vitamin D in the defense against falling serum calcium (Ca) concentrations following cord clamping has been suggested. Since race and season are known to affect vitamin D status, we theorized that black race and birth in winter are additional risk factors for neonatal hypocalcemia (NHC). We retrospectively studied 13,462 infants born at University Hospital (Cincinnati, OH) between January 1, 1984 and December 31, 1987. Serum Ca was measured at 24 hours of age routinely in infants with low birth weight (less than 2500 g), preterm delivery (less than 2500 g), preterm delivery (less than 37 weeks), neonatal asphyxia, and diabetic mothers. After exclusion of infants of diabetic mothers (to remove maternal diabetes as a major confounder) and infants with major congenital anomalies, 714 infants remained. In multiple regression analysis, low serum Ca values were significantly associated with low gestational age (p less than 0.01), low Apgar score (p less than 0.01), and white race (p less than 0.01) (R2 = 0.457). Season or month of birth was not significant. In pair-matched analysis controlling for factors other than season, season of birth did not affect serum Ca. In pair-matched analysis controlling for factors other than race, white race was once again a risk factor for hypocalcemia. Thus, low gestational age, low Apgar score, and white race, but not black race and delivery in winter, are risk factors for NHC. We speculate that in our climate and with the prevailing diet in pregnancy, vitamin D deficiency does not appear to play a role in NHC.(ABSTRACT TRUNCATED AT 250 WORDS)     

Preterm singleton births--United States, 1989-1996

Preterm birth (birth at <37 completed weeks of gestation) is the second leading cause of neonatal mortality in the United States. Preterm birthrates differ by race; in 1996, black infants were 1.8 times more likely than white infants to be preterm. From 1989 through 1996, the overall rate of preterm birth (per 1000 live-born infants) increased 4%, and the rate of multiple births (e.g., twins, triplets, or other higher-order births) increased 19%. Multiple births are associated with preterm birth; trends in preterm births independent of the influence of multiple births have not been fully explored. To characterize race- and ethnicity-specific trends in preterm birth independent of multiple births, data from U.S. birth certificates for 1989-1996 were analyzed for singleton births only. This report summarizes the results of this analysis and indicates that although singleton preterm birthrates are stable overall, substantial changes in rates occurred in some racial/ethnic subgroups.     

The effects of prenatal care upon the health of the newborn.

Data upon all births and infant deaths in New York City in 1968 are analyzed using methods for the analysis of multidimensional contingency tables. These methods provide estimates of the effect of variations in prenatal care upon the relative risks of low birth weight and neonatal and postneonatal mortality, controlling for a wide variety of factors which tend to "select" women into a program of prenatal care. Significant relationships between lack of prenatal care and infant mortality are estimated, but these occur mainly via the relationship of inadequate prenatal care to low birth weight. Furthermore, among white mothers who delivered on a private service, those receiving inadequate levels of prenatal care experienced only slightly increased risks of a low birth weight infant. In contrast, white mothers who delivered on a general service, and all black mothers, experienced substantially increased risks when receiving inadequate prenatal care. A variety of behavioral characteristics of mothers were not controlled in these analyses, and thus clear causal inferences concerning the efficacy of prenatal care cannot be drawn. These analyses do, however, identify a significant population of women at substantial risk.     

Overview of the National Infant Mortality Surveillance (NIMS) project--design, methods, results

The recent slowdown in the decline of infant mortality in the United States and the continued high risk of death among black infants (twice that of white infants) prompted a consortium of Public Health Service agencies to collaborate with all States in the development of a national data base from linked birth and infant death certificates. This National Infant Mortality Surveillance (NIMS) project for the 1980 U.S. birth cohort provides neonatal, postneonatal, and infant mortality risks for blacks, whites, and all races in 12 categories of birth weights. (Note: Neonatal mortality risk = number of deaths to infants less than 28 days of life per 1,000 live births; postneonatal mortality risk = number of deaths to infants 28 days to less than 1 year of life per 1,000 neonatal survivors; and infant mortality risk = number of deaths to infants less than 1 year of life per 1,000 live births.) Separate tabulations were requested for infants born in single and multiple deliveries. For single-delivery births, tabulations included birth weight, age at death, race of infant, and each of these characteristics: infant's live-birth order, sex, gestation, type of delivery, and cause of death; and mother's age, education, prenatal care history, and number of prior fetal losses at 20 weeks' or more gestation. An estimated 95 percent of eligible deaths were included in the NIMS tabulations. The analyses focus on three components of infant mortality: birth weight distribution of live births, neonatal mortality, and postneonatal mortality. The most important predictor for infant survival was birth weight, with an exponential improvement in survival by increasing birth weight to its optimum level. The nearly twofold higher risk of infant mortality among blacks was related to a higher prevalence of low birth weights and to higher mortality risks in the neonatal period for infants weighing 3,000 grams or more, and in the postneonatal period for all infants, regardless of birth weight. Regardless of other infant or maternal risk factors, the black-white gap persisted for infants weighing 2,500 grams or more.     

Trends in twin and triplet births: 1980-97.

This report presents data from U.S. birth certificates on the numbers and rates of twin and triplet and other higher order multiple births for 1980-97. Over the study period, the number of twin births rose 52 percent (from 68,339 to 104,137) and triplet and other higher order multiple births (heretofore referred to as "triplet/+") climbed 404 percent (from 1,337 to 6,737 births). Comparable but less pronounced rises were observed in twin and triplet/+ birth rates. Growth in twin and triplet/+ birth rates was most marked among women aged 30 years and over. Between 1980-82 and 1995-97, the twin rate rose 63 percent for women aged 40-44 years, and soared nearly 1,000 percent for women 45-49 years. (As one result, there were more twins born to women 45-49 years of age in 1997, than during the entire decade of the 1980's.) The triplet/+ birth rate rose nearly 400 percent for women in their thirties and exploded by more than 1,000 percent for women in their forties. The extraordinary rise in multiple births resulted in a shift in age-specific patterns, and the highest twin and triplet/+ birth rates now are for women 45-49 years of age. Historical differences in twinning rates between non-Hispanic white and black mothers have been largely eliminated (28.8 per 1,000 non-Hispanic white compared with 30.0 for black women). Non-Hispanic white women were more than twice as likely as non-Hispanic black or Hispanic women to have a triplet/+ birth. Rates of low birthweight, very low birthweight, and infant mortality were 4 to 33 times higher for twins and triplet/+ compared with singleton births. The risk for these adverse outcomes was lowest for twins and triplet/+ born to women 35-44 years of age. Twin birth rates for Massachusetts and Connecticut were at least 25 percent higher than the U.S. rate; triplet/+ rates for Nebraska and New Jersey were twice the national level.     

Disparities in Mortality Rates Among US Infants Born Late Preterm or Early Term, 2003–2005

The purpose of this study was to identify disparities in neonatal, post-neonatal, and overall infant mortality rates among infants born late preterm (34–36 weeks gestation) and early term (37–38 weeks gestation) by race/ethnicity, maternal age, and plurality. In analyses of 2003–2005 data from US period linked birth/infant death datasets, we compared infant mortality rates by race/ethnicity, maternal age, and plurality among infants born late preterm or early term and also determined the leading causes of death among these infants. Among infants born late preterm, infants born to American Indian/Alaskan Native, non-Hispanic black, or teenage mothers had the highest infant mortality rates per 1,000 live births (14.85, 9.90, and 11.88 respectively). Among infants born early term, corresponding mortality rates were 5.69, 4.49, and 4.82, respectively. Among infants born late preterm, singletons had a higher infant mortality rate than twins (8.59 vs. 5.62), whereas among infants born early term, the rate was higher among twins (3.67 vs. 3.15). Congenital malformations and sudden infant death syndrome were the leading causes of death among both late preterm and early term infants. Infant mortality rates among infants born late preterm or early term varied substantially by maternal race/ethnicity, maternal age, and plurality. Information about these disparities may help in the development of clinical practice and prevention strategies targeting infants at highest risk.     

Neonatal intensive-care unit admission of infants with very low birth weight --- 19 States, 2006

Neonatal mortality is disproportionately common among infants with very low birth weight (VLBW) (<1,500 g [3.3 lbs]). In 2006, the mortality rate among infants with VLBW was 240.4 per 1,000 live births. Because neonatal intensive care has been shown to reduce mortality among infants with VLBW, current standards call for neonatal intensive-care for all infants with VLBW; however, the proportion of infants with VLBW who are admitted to a neonatal intensive care unit (NICU) is not known, nor are the predictors for NICU admission. To estimate the prevalence of admission to NICUs among infants with VLBW and assess factors predicting admission, CDC analyzed birth data from 2006 for 19 states. This report summarizes the results of that analysis, which found that overall, 77.3% of infants with VLBW were admitted to NICUs (range: 63.7% in California to 93.4% in North Dakota). Among infants with VLBW born to Hispanic mothers, 71.8% were admitted to NICUs, compared with 79.5% of those with non-Hispanic black mothers and 80.5% of those with non-Hispanic white mothers. Multivariate analysis of the data indicated that preterm delivery, multiple births, and cesarean delivery all were independently associated with greater prevalence of NICU admission among infants with VLBW. Wide variation was observed among states in the prevalence of NICU admission of infants with VLBW; these state data should be assessed further, and barriers to NICU admission should be identified and addressed.     

Unintended births: patterns by race and ethnicity and relationship type

CONTEXT: Childbearing intentions vary by race and ethnicity and by relationship type. However, few studies have examined whether they differ by race and ethnicity within relationship type. METHODS: Data from the Early Childhood Longitudinal Study were used to examine the childbearing intentions of 9,100 mothers of a cohort of children born in 2001. Multivariate and multinomial regression analyses were conducted to examine whether relationship type (married, cohabiting or neither) helps explain racial and ethnic differences in childbearing intentions and whether associations between race and ethnicity and childbearing intentions vary by relationship type. RESULTS: Blacks were more likely than whites to have had an unintended birth (odds ratio, 2.5); the relationship held among married (2.6), but not unmarried, mothers. For most relationship types, black mothers had higher relative risks than whites of having had an unwanted birth, rather than an intended or a mistimed one. Asian married mothers were more likely than their white counterparts to have had an unwanted, rather than intended, birth (1.9). The odds of an unintended birth were lower among foreign‐born Hispanic cohabiting women than among white cohabiting women (0.6), a finding driven by the lower risk of unwanted than of other births among foreign‐born Hispanics (0.3–0.5). Few differences were apparent between native‐born Hispanics and white mothers. CONCLUSIONS: Racial and ethnic differences in childbearing intentions are frequently contingent on relationship context. Differences between whites and blacks are largely attributable to married women. Assessment of childbearing intendedness among Hispanics should take nativity into account.