Article

Risk of Very Low Birth Weight Based on Perinatal Periods of Risk

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  • Grand Rounds Inc
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Abstract

Objective To determine the risk factors associated with having a very low birth weight (VLBW) infant as a follow-up to the first phase of a Perinatal Periods of Risk approach.Design and SampleRetrospective cohort analysis of birth certificates. Population-based sample of 53,427 birth certificates for the city under study during the years 1999–2006.MeasuresThe relationship of selected maternal characteristics as predictors of VLBW using multivariate logistic regression analysis.ResultsThe maternal characteristics associated with VLBW were as follows: no prenatal care (OR = 4.04), inadequate weight gain (OR = 3.97), Black, non-Hispanic race (OR = 1.50), less than 20 years old (OR = 1.42) and more than 35 years old (OR = 1.43). After analyzing age and race/ethnicity together, Black non-Hispanic women less than 20 years of age (OR = 2.70) or over 35 years of age (OR = 2.45) still had an increased odds for having a VLBW infant whereas Black non-Hispanic women between the ages of 20 and 35 did not.Conclusions The findings of this study suggest educating women on the importance of preconception care, prenatal care, and adequate pregnancy weight gain to reduce the odds of having a VLBW infant.

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... Previous PPOR analyses have found that the maternal health/prematurity category, which by definition consists of all VLBW births and fetal deaths, is often the greatest contributor to excess infant mortality [6][7][8][9][10][11][12]. A PPOR analysis in Kansas City found that deaths due VLBW were a significant issue among African Americans [7]. ...
... The Kitagawa analyses, which are used to determine the contributors to excess deaths in the maternal health/prematurity category, found that among black infants, 44.5% of the excess deaths were attributed to the distribution of VLBW births, compared to 24.3% among white infants in Kansas City [7]. Other PPOR analyses have identified risk factors for VLBW that include maternal medical risk, maternal anemia, obstetric history, black maternal race, maternal age less than 20 years or greater than 35 years, smoking, inadequate/no prenatal care, parity, maternal weight gain less than 11 pounds, socioeconomic status, and single marital status [2,10,13]. ...
... The Kitagawa analysis shows that the majority of excess deaths among VLBW infants are due to birth weight distribution, meaning that a disproportionately large number of VLBW babies are being born in this community. Therefore, interventions designed to reduce the number of VLBW infants can help to reduce excess fetoinfant mortality BioMed Research International 5 marital status, and weight gain < 11 pounds as risk factors [10]. However, marital status and weight gain were not evaluated in our analysis; and maternal age < 20 was not associated with an increased risk of VLBW. ...
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Objective: Very low birth weight (VLBW) is a significant issue in St. Louis, Missouri. Our study evaluated risk factors associated with VLBW in this predominantly urban community. Methods: From 2000 to 2009, birth and fetal death certificates were evaluated (n = 160, 189), and mortality rates were calculated for perinatal periods of risk. The Kitagawa method was used to explore fetoinfant mortality rates (FIMR) in terms of birth weight distribution and birthweight specific mortality. Multivariable logistic regression was used to assess the magnitude of association of selected risk factors with VLBW. Results: VLBW contributes to 50% of the excess FIMR in St. Louis City and County. The highest proportion of VLBW can be attributed to black maternal race (40.6%) in St. Louis City, inadequate prenatal care (19.8%), and gestational hypertension (12.0%) among black women. Medicaid was found to have a protective effect for VLBW among black women (population attributable risk (PAR) = -14.5). Discussion: Interventions targeting the health of women before and during conception may be most successful at reducing the disparities in VLBW in this population. Interventions geared towards smoking cessation and improvements in Medicaid and prenatal care access for black mothers and St. Louis City residents can greatly reduce VLBW rates.
... Women under the age of 15 have also been found to have a significantly increased odds to have a baby that was VLBW (aOR 1.47) and significantly lower prevalence of adequate care (43 vs. 72 %), compared with women 15 years of age and older [8]. A study of birth certificate data from Colorado, found that no prenatal care (aOR 4.04), inadequate weight gain (aOR 3.97), Black, non-Hispanic race (aOR 1.50), maternal age \20 years (aOR 1.42) and greater than 35 years (aOR 1.43) were all significant risk factors of VLBW) [9]. In St. Louis City and County, VLBW has been reported as the greatest contributor to feto-infant mortality between 2000 and 2009, with inadequate prenatal care contributing to 17.3 % of the population attributable risk for VLBW [10]. ...
... In fact, a more recent study of prenatal care utilization among North Carolina teen mothers, using the adequacy of prenatal care utilization (APNCU), reported that prenatal care only explained 2 % of the variance regarding birth weight [16]. Importantly, concerns have been raised that these previous studies assessing the relationship between prenatal care and birth weight were faulty because the study designs did not sufficiently adjust for prematurity bias, selection bias, and other confounders such as maternal medical risks, race, maternal age, smoking, parity, maternal weight gain, and socioeconomic status [9]. ...
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Objectives: This study examined risk and protective factors associated with very low birth weight (VLBW) for babies born to women receiving adequate or inadequate prenatal care. Methods: Birth records from St. Louis City and County from 2000 to 2009 were used (n = 152,590). Data was categorized across risk factors and stratified by adequacy of prenatal care (PNC). Multivariate logistic regression and population attributable risk (PAR) was used to explore risk factors for VLBW infants. Results: Women receiving inadequate prenatal care had a higher prevalence of delivering a VLBW infant than those receiving adequate PNC (4.11 vs. 1.44 %, p < .0001). The distribution of risk factors differed between adequate and inadequate PNC regarding Black race (36.4 vs. 79.0 %, p < .0001), age under 20 (13.0 vs. 33.6 %, p < .0001), <13 years of education (35.9 vs. 77.9 %, p < .0001), Medicaid status (35.7 vs. 74.9, p < .0001), primiparity (41.6 vs. 31.4 %, p < .0001), smoking (9.7 vs. 24.5 %, p < .0001), and diabetes (4.0 vs. 2.4 %, p < .0001), respectively. Black race, advanced maternal age, primiparity and gestational hypertension were significant predictors of VLBW, regardless of adequate or inadequate PNC. Among women with inadequate PNC, Medicaid was protective against (aOR 0.671, 95 % CI 0.563-0.803; PAR -32.6 %) and smoking a risk factor for (aOR 1.23, 95 % CI 1.01, 1.49; PAR 40.1 %) VLBW. When prematurity was added to the adjusted models, the largest PAR shifts to education (44.3 %) among women with inadequate PNC. Conclusions: Community actions around broader issues of racism and social determinants of health are needed to prevent VLBW in a large urban area.
... Given the range of studies revealing associations between unintended pregnancy and a spectrum of adverse pregnancy outcomes even after controlling race, class and other potential confounders, these prevalence findings are of concern. The second body of relevant data is a set of PPOR (Perinatal Periods of Risk) studies conducted around the country (Demont-Heinrich et al. 2013;Besculides and Laraque 2005). Taken together, these analyses suggest that the challenges faced by U.S. women, and especially women who experience social marginalization based on race/ethnicity, income or both, arise prior to pregnancy, and the failure of our system to invest in improved women's health prior to pregnancy precludes opportunities to address those challenges. ...
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Objectives Preconceptional health care is increasingly recognized as important to promotion of healthy birth outcomes. Preconceptional care offers an opportunity to influence pregnancy timing and intent and mother’s health status prior to conception, all predictors of individual outcomes and of inequality in birth outcomes based on race, ethnicity and class. Methods One Key Question, a promising practice developed in Oregon which is now attracting national interest, provides an entry point into preconceptional care by calling on providers to screen for pregnancy intent in well woman and chronic disease care for women of reproductive age. For women who choose not to become pregnant or are not definitive in their pregnancy intent, One Key Question provides an opportunity for provision of or referral to counseling and contraceptive care. Results Adoption of One Key Question and preconceptional care as standard practices will require important shifts in medical practice challenging the longstanding schism between well woman care generally and reproductive care in particular. Adoption will also require shifts in cultural norms which define the onset of pregnancy as the appropriate starting point for attention to infant health. Conclusions for Practice This commentary reviews the case for preconceptional care, presents the rationale for One Key Question as a strategy for linking primary care to preconceptional and/or contraceptive care for women, outlines what is entailed in implementation of One Key Question in a health care setting, and suggests ways to build community support for preconceptional health.
... Mumbare SS confirmed that poor weight gain during pregnancy is a significant predictors for delivery of a low birth weight neonate [35]. Demont-Heinrich found inadequate weight gain and not receiving any prenatal care are top two risk factors associated with very low birth weight [36]. Birth weight was revealed to be positively correlated with gestational weight gain, and Ferrari N deemed that an excessive weight gain would accompanied by macrosomia [37]. ...
Article
Objective: To investigate the contributions of parental, especially paternal factors to the offspring birth weight. Methods: Eligible 829 live-born, singleton children living in Hubei, China were recruited. Birth weight were measured immediately after birth and information about the parents were collected by face-to-face interview using questionnaire. Association between parental factors and birth weight was evaluated using univariate linear regression and multinomial logistic regression models. Results: Fathers living in the rural area had offspring with higher risk of low birth weight when compared with fathers who live in the capital city. Maternal lower education, lower gestational weight gain, being primipara and shorter gestational age were risk factors for low birth weight. In addition, Mothers with the history of chronic disease had higher risk to deliver a low birth weight baby. On the contrary, women who increased non-staple food consumption during pregnancy had higher risk to have a macrosomic pregnancy. However, lifestyle factors including diet, exercise, screen time, drinking and smoking from both maternal and paternal exhibited little influence on fetal birth weight. Conclusion: Paternal as well as maternal factors exert influence on the fetal birth weight, although maternal factors make bigger contributions. Compared with socioeconomic and obstetric factors, lifestyle before and during pregnancy has less influence on fetal birth weight, suggested that special attention should be paid to antenatal care for the pregnant women with lower socioeconomic status in rural area.
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Background Low birth weight (LBW) is susceptible to neonatal complications, chronic medical conditions, and neurodevelopmental disabilities. We aim to describe the determinants of very low birth weight (VLBW) in India and compare it with the determinants of LBW based on the National Family Health Survey – 4 (NHFS-4) Methods Data from the NFHS-4 on birthweight and other socio-demographic characteristics for the youngest child born in the family during the five years preceding the survey were used. Data of 147,762 infant–mother pairs were included. Multiple logistic regression models were employed to delineate the independent predictors of VLBW (birth weight<1500 g) or LBW (birth weight: 1500-2499 g). Results Of the 147,762 children included in the study, VLBW and LBW were observed in 1.2% and 15.8% of children, respectively. The odds of VLBW were higher in female children (aOR: 1.36, 95% CI: 1.15–1.60), among mothers aged 13–19 years (aOR: 1.58, 95% CI: 1.22–2.07), mothers with severe or moderate anaemia (aOR: 1.61, 95% CI: 1.34–1.94), mothers without recommended antenatal care (aOR: 1.47, 95% CI: 1.31–1.90), maternal height less than 150 cm (aOR: 1.54, 95% CI: 1.29–1.85) and among mothers with multiple pregnancy (aOR: 21.34, 95% CI: 14.70–30.96) in comparison to their corresponding counterparts. In addition to the variables associated with VLBW, educational status of mothers (no education; aOR: 1.08, 95% CI: 1.02–1.15 and primary education; aOR: 1.16, 95% CI: 1.08–1.25), caste of the children (scheduled tribe; aOR: 1.13, 95% CI: 1.03–1.24), and wealthiness of the family (poorest wealth quintiles; aOR: 1.11, 95% CI: 1.03–1.19) were associated with LBW. Conclusions Interventions targeting improvements in antenatal care access, maternal health, and nutritional status may reduce the number of VLBW infants. Social determinants of LBW require further detailed study to understand the high propensity of low birth-weight phenotypes in the disadvantaged communities in India.
Article
Background Low birth weight (LBW) is susceptible to neonatal complications, chronic medical conditions, and neurodevelopmental disabilities. We aim to describe the determinants of very low birth weight (VLBW) in India based on the National Family Health Survey – 4 (NHFS-4). Methods Data from the NFHS 4 on birthweight and other socio-demographic characteristics for the youngest child born in the family during the five years preceding the survey were used. Data of 147,762 infant–mother pairs were included. Multiple logistic regression models were employed to delineate the independent predictors of VLBW (birth weight<1500 g) or LBW (birth weight <2500 g). Results Of the 147,762 children included in the study, VLBW and LBW were observed in 1.2% and 15.8% of children, respectively. The odds of VLBW were higher in female children (aOR: 1.36, 95% CI: 1.15–1.60), among mothers aged 13–19 years (aOR: 1.58, 95% CI: 1.22–2.07), mothers with severe or moderate anaemia (aOR: 1.61, 95% CI: 1.34–1.94), mothers without recommended antenatal care (aOR: 1.47, 95% CI: 1.31–1.90), maternal height less than 150 cm (aOR: 1.54, 95% CI: 1.29–1.85) and among mothers with multiple pregnancy (aOR: 21.34, 95% CI: 14.70–30.96) in comparison to their corresponding counterparts. In addition to the variables associated with VLBW, educational status of mothers (no education; aOR: 1.08, 95% CI: 1.02–1.15 and primary education; aOR: 1.16, 95% CI: 1.08–1.25), caste of the children (scheduled tribe; aOR: 1.13, 95% CI: 1.03–1.24), and wealthiness of the family (poorest wealth quintiles; aOR: 1.11, 95% CI: 1.03–1.19) were associated with LBW. Conclusions Interventions targeting improvements in antenatal care access, maternal health, and nutritional status may reduce the number of VLBW infants. Social determinants of LBW require further detailed study to understand the high propensity of low birth-weight phenotypes in the disadvantaged communities in India.
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To study the prevalence of low birth weight (LBW) and its association with maternal factors. Cohort study. Urban community. Cohort of 210 pregnant women. The LBW prevalence was 30.3%. On multivariate analyses the maternal factors significantly associated with LBW were anemia (OR-4.81), low socioeconomic status (OR-3.96), short birth interval (OR-3.84), tobacco exposure (OR-3.14), height (OR-2.78), maternal age (OR-2.68), body mass index (OR-2.02), and primiparity (OR 1.58). Anemia, low socioeconomic status, short stature, short birth interval. Tobacco exposure, low maternal age, low body mass index, and primiparity are significantly risk factors for LBW.
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Conference Paper
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Abstract For morethan two decades, prenatal care has been a cornerstone of our nation?s strategy for preventing low birthweight (LBW). The enrollment of all pregnant women in prenatal care was promoted by the seminal 1985 Institute of Medicine report Preventing Low Birthweight (IOM, 1985a), following a comprehensive review of the literature by a select IOM committee on the effectiveness of prenatal care for preventing LBW. Because LBW contributes significantly to racial-ethnic disparities in infant mortality and morbidity, increasing access to prenatal care for all women has also become established as the key population-based public health intervention to address racial-ethnic disparities in perinatal outcomes. The purpose of this chapter is to review evidence on the overall effectiveness of prenatal care in preventing LBW and reducing racial-ethnic disparities in LBW.
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To identify the risk factors responsible for differences in birth weight between blacks and whites, we investigated the effects of four maternal characteristics (age, parity, marital status, and education) on rates of very low birth weight (less than 1500 g) and moderately low birth weight (between 1500 and 2500 g). Using 1983 national data, we found that the black:white rate ratio was 3.0 for very low birth weight and 2.3 for moderately low birth weight. The four maternal factors had directionally similar but quantitatively different effects on very low and moderately low birth weight among blacks and whites. Furthermore, the racial differences in infants' birth weights were greater among low-risk than among high-risk mothers, especially for very low birth weight (black:white ratios of 3.4 and 1.7, respectively). We also examined secular trends in the rates of low birth weight among blacks and whites. Between 1973 and 1983, births of infants with moderately low birth weights decreased more among whites than among blacks, whereas births of infants with very low birth weights increased among blacks and decreased among whites. Fifteen percent of the decline in the rate of moderately low birth weight among whites could be attributed to favorable changes in maternal characteristics (primarily an increase in educational level). Among blacks, adverse changes in maternal characteristics (primarily an increase in births to unmarried women) accounted for 35 percent of the increase in the rate of very low birth weight. The adverse effects of childbearing by teenagers on the outcome of pregnancy among blacks appear to have been overemphasized. The persistence of large racial differences in birth weight, even among mothers at low risk, emphasizes the need for specific targeted interventions to achieve further improvements in infant health.
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This study examined long-term trends and differences in infant mortality in the United States from 1950 through 1991 according to race and ethnicity, education, family income, and cause of death. Forecasts are made through the year 2010. Log-linear regression models were applied to data from the National Vital Statistics System, National Linked Birth and Infant Death files, the National Maternal and Infant Health Survey, the National Natality Survey, and the National Infant Mortality Survey to model and forecast infant mortality. Dramatic declines in the US infant mortality rate have occurred in the past 4 decades, largely as a result of declines in mortality from pneumonia and influenza, respiratory distress syndrome, prematurity and low birthweight, congenital anomalies, and accidents. Despite the overall reductions, however, substantial racial/ethnic, educational, and income differences in infant mortality still exist. The long-term downward trend in US infant mortality has not benefited Blacks and Whites equally. The Black/White disparity in infant mortality has not only persisted but increased over time and is not expected to diminish in the near future. Educational inequalities have also widened, and racial disparities have generally increased across all educational levels.
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Prenatal care has long been endorsed as a means to identify mothers at risk of delivering a preterm or growth-retarded infant and to provide an array of available medical, nutritional, and educational interventions intended to reduce the determinants and incidence of low birth weight and other adverse pregnancy conditions and outcomes. Although the general notion that prenatal care is of value to both mother and child became widely accepted in this century, the empirical evidence supporting the association between prenatal care and reduced rates of low birth weight emerged slowly and has been equivocal. Much of the controversy over the effectiveness of prenatal care in preventing low birth weight stems from difficulties in defining what constitutes prenatal care and adequate prenatal care use. While the collective evidence regarding the efficacy of prenatal care to prevent low birth weight continues to be mixed, the literature indicates that the most likely known targets for prenatal interventions to prevent low birth weight rates are (1) psychosocial (aimed at smoking); (2) nutritional (aimed at low prepregnancy weight and inadequate weight gain); and (3) medical (aimed at general morbidity). System level approaches to impact the accessibility and the appropriateness of prenatal health care services to entire groups of women and population-wide health promotion, social service, and case management approaches may also offer potential benefits. However, data on the effectiveness of these services are lacking, and whether interventions focused on building cohesive, functional communities can do as much or more to improve low birth weight rates as individualized treatments has yet to be explored. The ultimate success of prenatal care in substantially reducing current low birth weight percentages in the United States may hinge on the development of a much broader and more unified conception of prenatal care than currently prevails. Recommendations for actions to maximize the impact of prenatal care on reducing low birth weight are proposed both for the public and for the biomedical, public health, and research communities.
Article
To study the consequences of delayed first childbearing in a large, population-based US sample, with separate analysis of women aged 40 years or more and adjustment for socioeconomic factors, smoking, medical and reproductive conditions, and route of delivery. Retrospective survey of Washington State birth certificates from 1984 through 1988. First liveborn singleton infants of women aged at least 20 years. Of eligible white infants, all those born to women aged 35 to 39 years (n = 4019) and 40 years or more (n = 410) and a maternal age-stratified random sample of white infants of younger women were studied. All eligible black infants were studied. Low (< 2500 g) and very low (< 1500 g) birth weight and preterm delivery (< 37 weeks of gestation). Adjusted odds ratios for delivering a low-birth-weight white infant increased progressively with each 5-year maternal age group, reaching 2.3 (95% confidence interval, 1.6 to 3.4) for women aged 40 years or more compared with those aged 20 to 24 years. The maternal age effects for very low birth weight and preterm delivery were similar; for each, the odds ratio was 1.8 for the oldest group. No significant maternal age effect was found among births of black infants, but only 127 births to women aged 35 years or more were studied. Increasing maternal age at first childbirth is an independent risk factor for low birth weight and preterm delivery of white infants in the United States.
Article
Despite decreases in the last 50 years, infant mortality rates in the United States remain higher than in other industrialized countries. Using overall infant mortality rates to determine the effectiveness of interventions does not help communities focus on particular underlying factors contributing to static, and sometimes increasing, community rates. This study was designed to determine and rank contributing factors to fetal-infant mortality in a specific community using the Perinatal Periods of Risk (PPOR) model. The PPOR model was used to map fetal-infant mortality for 1995 to 1998 in the Tulsa, Oklahoma, Healthy Start Program as compared to traditional calculation methods. The overall fetal-infant mortality rate using the PPOR model was 12.7 compared to 7.11 calculated using the traditional method. The maternal health cell rate was 5.4, maternal care cell rate was 2.9, newborn care cell was 1.9 compared to a 4.1 neonatal death rate calculated using the traditional method, and the infant health cell was 2.4 compared to a 2.9 postneonatal rate calculated using the traditional method. Because the highest infant mortality was in the maternal health cell, intervention strategies were designed to promote the health of women prior to and between pregnancies. The PPOR model was helpful in targeting interventions to reduce fetal-infant mortality based on the prioritization of contributing factors.
Article
We investigated the association between high parity and fetal morbidity outcomes. We analyzed 22,463,141 singleton deliveries at 20 weeks or more of gestation in the United States from 1989 through 2000. Adjusted odds ratios generated from logistic regression models were used to approximate relative risk for neonatal morbidity in women with 1-4 (moderate parity or type I; referent group), 5-9 (high parity or type II), 10-14 (very high parity or type III) and 15 or more (extremely high parity or type IV) prior live births. Main outcome measures included low and very low birth weight, preterm and very preterm birth, and small and large for gestational age delivery. The overall crude rates for low birth weight, very low birth weight, preterm birth, very preterm birth, and small and large for gestational age were 55, 11, 97, 19, 83, and 129 per 1,000 live births, respectively. The adjusted odds ratios for low birth weight, very low birth weight, preterm, and very preterm delivery increased consistently and in a dose-effect fashion with ascending parity (P for trend < .001). In the case of large for gestational age delivery, the adjusted odds ratio showed an inverted-U pattern, being highest among women in the type III parity cluster. The findings with respect to small for gestational age were inconclusive. High parity is a risk factor for adverse fetal outcomes. However, the impact of heightened parity is more manifest as shortened gestation rather than physical size restriction. These findings could prove beneficial for counseling women of high parity.
Article
The Perinatal Periods of Risk (PPOR) technique was used to analyze resident fetal and infant death data from Kansas City, Missouri, for the period 1998-2002. Results offer important information that can be used to develop community-based prevention strategies related to racial/ethnic disparities in infant mortality rates (IMR). The PPOR approach for fetal and infant mortality can be mapped by birthweight at delivery and time of death into four strategic prevention areas: 1) Maternal Health/Prematurity (MHP), 2) Maternal Care (MC), 3) Newborn Care (NC), and 4) Infant Health (IH). For this analysis, all fetal and infant death certificates from the metropolitan Kansas City area were linked to their birth certificates and those associated with residents of Kansas City, Missouri, proper were used to create the dataset used in this analysis. Due to the small number of fetal and infant deaths among other ethnic groups, the analysis was restricted to a comparison of the disparity of IMR between Blacks, Whites, and a national non-Hispanic white reference group. The Kitagawa formula was used to determine contribution to excess deaths from birthweight-specific mortality and birthweight distribution rates. Logistic regression techniques were used to identify risk factors for death among Black fetuses and infants with very low birthweights and also deaths due to sudden infant death syndrome (SIDS). The PPOR analysis showed that of the excess deaths among black infants, when compared to a national reference group, 47% was attributable to MHP and another 29% was attributable to IH. Differences in MC and NC only accounted for 27 and 8% of the total excess deaths. During the study period, rates of sudden infant death syndrome (SIDS) were found to be significantly higher among Blacks as compared to Whites (2.12 vs. 0.81 per 1,000). An analysis of maternal characteristics for SIDS deaths among blacks using a step-wise logistic regression model, found that maternal age less than 20 years old, previous births, inadequate prenatal care, and being a Medicaid recipient were significant-adjusted odds ratios of 23.7 (95% Cl 10.48, 53.67), 8.4 (95% Cl 3.64, 19.21), 2.9 (95% Cl 1.38, 6.05) and 2.5 (95% Cl 1.04, 5.84), respectively. PPOR is an easy to use approach that helps focus community initiatives for improving maternal and infant health. In Kansas City, Missouri, efforts to further lower IMR in blacks can be achieved through the reduction of risk factors affecting maternal health and through maternal education to improve infant health.
Article
Pregnancy outcomes in the United States and other developed countries are considerably better than those in many developing countries. However, adverse pregnancy outcomes are generally more common in the United States than in other developed countries. Low-birth-weight infants, born after a preterm birth or secondary to intrauterine growth restriction, account for much of the increased morbidity, mortality, and cost. Wide disparities exist in both preterm birth and growth restriction among different population groups. Poor and black women, for example, have twice the preterm birth rate and higher rates of growth restriction than do most other women. Low birth weight in general is thought to place the infant at greater risk of later adult chronic medical conditions, such as diabetes, hypertension, and heart disease. Of interest, maternal thinness is a strong predictor of both preterm birth and fetal growth restriction. However, in the United States, several nutritional interventions, including high-protein diets, caloric supplementation, calcium and iron supplementation, and various other vitamin and mineral supplementations, have not generally reduced preterm birth or growth restriction. Bacterial intrauterine infections play an important role in the etiology of the earliest preterm births, but, at least to date, antibiotic treatment either before labor for risk factors such as bacterial vaginosis or during preterm labor have not consistently reduced the preterm birth rate. Most interventions have failed to reduce preterm birth or growth restriction. The substantial improvement in newborn survival in the United States over the past several decades is mostly due to better access to improved neonatal care for low-birth-weight infants.
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