Risk Factor For Low Birth Weight Research Articles

Neighborhood risk factors for low birthweight in Baltimore: a multilevel analysis.

Past research on low birthweight has focused on individual-level risk factors. We sought to assess the contribution of macrolevel social factors by using census tract-level data on social stratification, community empowerment, and environmental stressors. Census tract-level information on social risk was linked to birth certificate records from Baltimore, Md, for the period 1985 through 1989. Individual level factors included maternal education, maternal age, medical assistance health insurance (Medicaid), and trimester of prenatal care initiation. Methods of multilevel modeling using two-stage regression analyses were employed. Macrolevel factors had both direct associations and interactions with low birthweight. All individual risk factors showed interaction with macrolevel variables; that is, individual-level risk factors for low birthweight behaved differently depending upon the characteristics of the neighborhood of residence. For example, women living in high-risk neighborhoods benefited less from prenatal care than did women living in lower-risk neighborhoods. Multilevel modeling is an important tool that allows simultaneous study of macro- and individual-level risk factors. Multilevel analyses should play a larger role in the formulation of public health policies.

Análisis multifactorial de los factores de riesgo de bajo peso al nacer en Salvador, Bahia

This study is a multifactorial analysis of the risk factors for low birthweight in a group of newborns in an urban area of Brazil. A total of 1023 infants born in four maternity units in Salvador, Bahia, between July 1987 and February 1988 were included in the study. The sources of information were clinical histories and interviews with the mothers in the maternity units. The analysis was by means of logistic regression. In the final model the risk factors were the following: maternal age less than 21 years or more than 35; gestational age less than 38 weeks; unfavorable outcome of an earlier pregnancy; interval of 12 months or less since prior birth; tobacco smoking; and hypertension. The population attributable risk values for the risk factors included in the final model are presented. These factors should be used to identify pregnant women at high risk of giving birth to a low-birthweight baby, in order to provide them with more prenatal care.

Ethnic differences in birthweight: the role of lifestyle and other factors.

The purpose of this study was to expand the search for risk factors for low birthweight and to find new explanations for the ethnic-group disparities in birth outcomes. The subjects were 1150 pregnant women from six ethnic groups (African American, Chinese, Dominican, Puerto Rican, Mexican, and White) who received prenatal care at clinics in New York and Chicago between December 1987 and December 1989. Two interviews were conducted during the second and third trimesters of pregnancy. The study, after controlling for poverty and other birthweight correlates, showed that living in public housing and believing that chance plays a major role in determining one's health status were negatively associated with birthweight. Having a stable residence was positively related to birthweight. Material hardship, social adversity, perceived racial discrimination, physical abuse, anxiety, and depression were not associated with birthweight. The negative role of an impoverished living environment and feelings of helplessness, as well as the positive role of having a stable form of social support, suggest new directions for research on the causes of low birthweight and the ethnic disparities in US birth outcomes.

Risk factors for low birth weight in a rural community in southern Brazil

This paper reports a study assessing risk factors for low birth weight (LBW), preterm and intrauterine growth retardation (IUGR) in a sample of 936 mothers who delivered babies in the Canguçu Hospital, a rural area of southern Brazil. Traditional risk factors for delivering LBW, preterm and IUGR were examined. The relative importance of the risk factors was studied through risk calculation and logistic regression analysis. Some risk factors for LBW such as low maternal education and number of prenatal consultations were not associated with the risk of delivering babies in any of the three risk groups. Hospitalization during pregnancy and maternal age less than 20 years were confirmed as risk factors for LBW. In the preterm group, low maternal weight and hospitalization during pregnancy showed significant association after control for confounders. The results suggest that there are specific targets for intervention in each of the three groups, and some traditional risk factors must be redefined according to the characteristics of each population.

Biologic risk factors for low birthweight in Al Ain, United Arab Emirates.

A prospective study of biological factors for low birthweight (LBW) among UAE nationals in the Al Ain Medical District was undertaken from 15 January 1992 to 14 January 1993, using a case control method. All 293 mothers of LBW infants and an equal number of mothers of the next normal weight infants born after the LBW infant were studied. Of the 3,485 live births, 293 (8.4%) were LBW (less than 2,500 g). Maternal age less than 25 years, lighter weight at booking, nulliparity, first cousin marriage and short interpregnancy interval (IPI) of 3 months or less significantly increased the risk of LBW in this population. After adjusting for other biologic confounders, only low maternal weight and short IPI significantly increased the risk of LBW. Modification of these biologic risk factors would help to reduce the incidence of LBW among the UAE population. © 1996 Wiley-Liss, Inc.

Biologic risk factors for low birthweight in Al Ain, United Arab Emirates

Biologic risk factors for low birthweight in Al Ain, United Arab Emirates

The influence of fetal and maternal factors on the distribution of birthweight

This review of common risk factors for low birthweight emphasizes the usefulness of examining the entire distribution of birthweight. Of the factors we examined, only short gestational age seemed to affect the low end of the birthweight distribution in the form of skewness. Most factors, such as maternal race, infant sex, plurality, altitude, education, and smoking seem to affect the entire birthweight distribution, indicating a generalized effect. With the exceptions of race, infant sex, parity, and altitude, these factors seemed to have similar associations with both low birthweight and infant mortality. However, only the effects of race and sex on mortality have been repeatedly studied in detail for different combinations of gestational age and birthweight. A few of the factors examined, notably infant sex and parity, have opposite associations with birthweight and infant mortality. Female infants and firstborn infants have lower birthweights than their counterparts, but are more likely to survive. For factors that significantly affect the birthweight distribution, but do not affect mortality equally across the birthweight distribution, the development and use of population-based standards may result in less misclassification of IUGR. Separate standards by infant sex, altitude, and perhaps race may lead to more accurate classification of intrauterine growth. Last, the majority of risk factors have differential effects on birthweight depending on the level of the associated factors. For example, low maternal age and low prepregnancy BMI are associated with both increased risk of low birthweight and poor infant survival. Older maternal age and high prepregnancy BMI are associated with reduced risk of low birthweight, but with increased risk of infant mortality. One possible explanation is that young maternal age and low prepregnancy BMI are associated with adverse behavioral risk factors such as cigarette smoking, whereas increased age and high prepregnancy BMI are associated with gestational diabetes, multiparity, and genetic defects. It is possible that the greater variation in birthweight at the high end of the scale is indicative of increased risk of mortality. Thus, higher birthweight does not always equal better birth outcomes.

Changes in risk factors for unfavorable pregnancy outcome among singletons over twenty years

To examine the change in the prevalence and relative effect of pre-pregnancy risk factors for low birthweight and/or stillbirth and/or neonatal mortality over a period of twenty years. Two prospectively collected one year birth cohorts. The two northernmost administrative districts of Finland. A birth cohort for 1966 comprising 11905 singleton births and a cohort for 1985-86 containing a further 9247. Risk factors for poor pregnancy outcome. In twenty years the prevalence of low birthweight infants among singletons decreased from 4.2% to 3.1% and that of stillbirths and neonatal deaths from 2.4% to 0.9%. The impact of single marital status decreased and while maternal age < 19 years was not an independent risk factor, the age > or = 35 years related more to poor pregnancy outcome. The proportion of multiparous women was halved but multiparity had a protective influence on pregnancy outcome meanwhile the impact of primiparity decreased markedly. In spite of more effective health education, the prevalence of heavy smokers was 4 times higher in the 1980s as compared with the 1960s, and its impact on adverse outcomes increased, with odds ratio (OR) 1.72 (confidence interval (CI) 1.14-2.61) in 1966 and OR 2.15 (CI 1.61-2.88) in 1985-86. The number of mothers with a previous low birthweight baby was halved but the impact of low birth weight was still great in the latter cohort (OR 2.47; CI 1.64-3.71). The impact of an earlier stillbirth and/or neonatal death increased significantly, with an OR 1.53 (CI 1.10-2.14) in 1966 and OR 2.95 (CI 1.81-4.81) in 1985-86, but the number of mothers concerned was halved from that in 1966. The prevalence of pregnancies with an adverse outcome decreased markedly, as did the prevalence of many of the risk factors. The proportion of > or = 35 years old parturients and of heavy smokers increased. The impact of primiparity decreased, while that of a previous outcome as assessed from pre-pregnancy factors has not improved in these twenty years, especially where primiparous parturients are concerned.

Determinants of low birthweight: a comparative study

The study compares biological, socioeconomic and behavioural determinants of low birthweight in Cameroon and the United States. Some factors in low birthweight are found to be cross-national, but others are specific to the setting. Positive risk factors of low birthweight in both countries include unmarried motherhood, female sex, multiple births, and preterm births. Outcome of the previous pregnancy is a positive risk factor in the US, but not in Cameroon. Significant negative risk factors include prenatal care visits (in both countries), mother's education (in the US only), births to mothers aged 20-34 and birth orders of 2 or more (in Cameroon only). Separate analyses of all births and the subsamples of singleton births reveal that estimates for the two groups differ only marginally.

Characteristics of Maternal Employment During Pregnancy

BACKGROUND: Although maternal employment is considered a risk factor for low birthweight (LBW), the manner in which employment might affect birthweight is poorly understood. In this analysis, selected characteristics of employment during pregnancy were examined for effects on pregnancy outcomes. METHODS: Work characteristics included the number of hours per week, physical activities, and environmental conditions. The outcomes of interest were fetal growth retardation (less than 2500 grams at term) and preterm delivery (less than 37 weeks). The study population consisted of 2711 non-Black, married mothers who participated in the 1980 National Natality Survey (NNS). The NNS data were merged with data from the 1977 revision of The Dictionary of Occupational Titles (DOT) from which measures of occupational physical activities and environmental exposures were obtained. Logistic regression was used in the analysis. RESULTS: Those who worked 40 or more hours per week were more likely than women who worked fewer ...

Risk factors for preterm and term low birthweight in Ahmedabad, India.

To identify and quantify risk factors for preterm and term low birthweight (LBW) we conducted a hospital-based case-control study, linked with a population survey in Ahmedabad, India. The case-control study of 673 term LBW, 644 preterm LBW cases and 1465 controls showed that low maternal weight, poor obstetric history, lack of antenatal care, clinical anaemia and hypertension were significant independent risk factors for both term and preterm LBW. Short interpregnancy interval was associated with an increased risk of preterm LBW birth while primiparous women had increased risk of term LBW. Muslim women were at a reduced risk of term LBW, but other socioeconomic factors did not remain significant after adjusting for these more proximate factors. Estimates of the prevalence of risk factors from the population survey was used to calculate attributable risk. This analysis suggested that a substantial proportion of term and preterm LBW births may be averted by improving maternal nutritional status, anaemia and antenatal care.

Characteristics of maternal employment during pregnancy: effects on low birthweight.

Although maternal employment is considered a risk factor for low birthweight (LBW), the manner in which employment might affect birthweight is poorly understood. In this analysis, selected characteristics of employment during pregnancy were examined for effects on pregnancy outcomes. Work characteristics included the number of hours per week, physical activities, and environmental conditions. The outcomes of interest were fetal growth retardation (less than 2500 grams at term) and preterm delivery (less than 37 weeks). The study population consisted of 2711 non-Black, married mothers who participated in the 1980 National Natality Survey (NNS). The NNS data were merged with data from the 1977 revision of The Dictionary of Occupational Titles (DOT) from which measures of occupational physical activities and environmental exposures were obtained. Logistic regression was used in the analysis. Those who worked 40 or more hours per week were more likely than women who worked fewer hours to have a low birthweight delivery at greater than or equal to 37 weeks. No physical or environmental characterics of work were associated with low birthweight or preterm delivery. Non-Black married American women may face a risk of delivering low-birthweight babies at or near term only if they work 40 or more hours each week. However, the lack of risk associated with other characteristics of work may be a function of measurement error in the DOT data source or of low levels of exposure in the analysis population.

Determinants of Preterm Delivery and Intrauterine Growth Retardation in North-East Brazil

A case-control study was conducted in Natal, north-east Brazil to determine the risk factors for low birthweight (LBW). Cases were 429 preterm and 422 intrauterine growth retarded (IUGR) singleton infants. Controls were 2555 infants of normal birthweight and gestational age. The prevalence of LBW was 10% (5.1% preterm and 4.9% IUGR). Logistic regression was used to estimate the adjusted odds ratios of LBW, and attributable risk per cent (AR%) was used to estimate the proportion of LBW that might be prevented. The preventable determinants of preterm delivery were births to women less than 20, (AR = 7.1%), low maternal weight less than 50 kg (AR = 20.5%), smoking during pregnancy (AR = 14.6%) and infrequent antenatal visits (AR = 28.1%). Other important determinants of preterm delivery were prior LBW births, gestational illness and vaginal bleeding. The main preventable causes of IUGR were low maternal weight (AR = 17.8%), low maternal education (AR = 11.6%), smoking (AR = 14.8%), and inadequate antenatal care (AR = 11.6%). Other risk factors for IUGR include primiparity, prior LBW births, and illness during gestation. In this population, the focus of short-term preventive programme should be improvement in maternal nutrition, cessation of smoking, reduction of births to women under 20, and improved antenatal care.

Risk factors for low birthweight in Singapore: strategies for prevention

An analysis of 9399 consecutive singleton births delivered at this unit is presented. The incidence of low birthweight (< 2500 g) was 7.4%. Further analysis of the 698 low birth weight babies indicated that a variety of socio-demographic risk factors are operational in the etiology of low birthweight. Many of these are preventable before pregnancy so that the implementation of preventive Public Health measures utilising appropriate technology at least in developing countries may be socially and economically preferable to continued financial investment in intensive perinatal services.

A comparison of women in and out of a prematurity prevention project in a North Carolina perinatal care region.

We assessed a prematurity prevention project in a North Carolina region with 21,000 annual births in terms of its impact on low birthweight. Project records were matched to birth certificates in order to compare characteristics of women in and out of the program who received prenatal care from private providers. A logistic regression analysis, in which the effects of race, marital status, age, and other risk factors for low birthweight were statistically controlled, showed that women not in the project were 1.32 times (95% Confidence Interval 1.14, 1.54) as likely as project participants to have a birth under 2500 grams. The relative risk for non-participants for a birth under 1500 grams was 1.87 (95% CI 1.25, 2.80). Strengths and limitations of the study are discussed. The results are consistent with previous work examining the etiologies of low birthweight in private versus public patients.

Short interpregnancy interval: a risk factor for low birthweight.

In a prospective study of 1683 women delivering at Yale-New Haven Hospital during 1980 through 1982, those conceiving within 1-4 months of a prior live birth were at increased risk of delivering a low birthweight (less than 2500 gm) newborn (RR = 5.70, 95% Cl = 0.83, 39.75), as were those conceiving 5-8 months later (RR = 3.25, 95% Cl = 1.02, 10.34), when compared with women conceiving 9 or more months later. Adjustment was made for maternal age, ethnicity, preterm delivery or low birthweight of prior newborn, and cigarette smoking in pregnancy. Gestational age of the second delivery was not affected by interpregnancy interval. These results may explain earlier reports of increased perinatal mortality after short birth intervals.

Did low birthweight among US blacks really increase?

The low birthweight (LBW) rate among reported United States non-White births increased 32 per cent from 1950 to 1967. States with large increments in non-White LBW rates over the period 1950-67 ("rising LBW states") were compared to states with more stable LBW rates. Paradoxically, states with the most deterioration in LBW rates had the most improvement in LBW risk factors (low income, mothers under age 20 or over age 35, birth order over four). In 1950, at least 9.7 per cent of non-White births in rising LBW states went unreported, and underreporting was biased, with out-of-hospital LBW births who die young least likely to be reported. From 1950 to 1967, non-White out-of-hospital births for the US declined from 42 per cent to 7 per cent, and yearly values for per cent of non-White births in hospital and LBW rates were highly correlated (r = .98). These data suggest that the observed rise in non-White LBW rates from 1950 to 1967 was due in large part to systematic underreporting of LBW births among non-White out-of-hospital deliveries in the 1950s. This underreporting essentially ceased when hospital delivery for non-Whites became nearly universal in the late 1950s and 1960s.

Effects of moderate alcohol consumption and smoking on fetal outcome.

Previous studies of the effects of moderate drinking on the outcome of pregnancy are assessed. The results of a prospective study of the association between alcohol consumption in pregnancy and birthweight, length of baby, head circumference and premature delivery are described. Consumption of more than 10 g alcohol per day in very early pregnancy or even before conception approximately doubled the risk that the infant would have a low birthweight. Cigarette smoking was also a risk factor for low birthweight. It may therefore be beneficial for women to reduce their alcohol consumption to one drink a day or less from before conception and give up smoking as well.

The risk of low birthweight.

Descriptive analyses of birthweight for single live births in the United States during 1974, using birth certificate information, show that several factors are associated with a high incidence of low birthweight babies. Multivariate analyses were performed to determine correlates of low birthweight. When other factors are held constant, race not white, previous reproductive loss, short interpregnancy interval, out-of-wedlock birth, no prenatal care, and maternal age under 18 years or over 35 years each increase the risk of having an infant of low birthweight. High birth order and maternal education under 12 years of schooling were not consistent risk factors for low birthweight. Odds ratios are presented and the method for combining these, to estimate the risk for an individual mother having a low-birthweight infant, is illustrated.

Maternal factors affecting low birth weight in urban area of Bangladesh

Objectives: In Bangladesh low birth weight (LBW) rate is quite high even in urban area. The present study was conducted to determine the maternal factors (e.g. socioeconomic, nutritional and pregnancy related) affecting LBW in urban community of Bangladesh. Methods: This case control study was done at Shaheed Shohrawardy Medical College Hospital, Dhaka. Normally delivered singleton live births babies from January 2003 to January 2005 in obstetrics wards were selected purposively and after enrollment all newborn's birth weight was measured. Then from the total (N=583) study populations child-mother pairs formed and were divided in LBW group (n=135) and normal birth weight (NBW) group (n=448). Maternal socioeconomic, nutritional and pregnancy regarding data (e.g. parity, inter pregnancy interval, number of antenatal visits) were collected and then variables were analyzed to find out maternal factors affecting LBW. Results: The LBW incidence was found 23.2% and mean birth weight was found 2762 gm. More proportion of LBW babies came from the mother of &lt;20year of age group. Significant relationship was found between early maternal age, education, socioeconomic status, anaemia, iron &amp; vitamin supplementation during pregnancy, maternal weight, body mass index (BMI) with LBW. Parity, inter pregnancy interval and number of antenatal visit were also found significant risk factors for LBW. No relationship was found between tobacco use and maternal height with LBW. Conclusion: Among the various epidemiological factors the maternal factors like antenatal care, parity, inter pregnancy interval, iron &amp; vitamin supplementation during pregnancy are found to influence birth weight. Hence, it is the need of the hour to strengthen the existing maternal services at the community level to reduce LBW in Bangladesh. Key words: LBW (Low Birth Weight); NBW (Normal Birth Weight). DOI: 10.3329/jdmc.v18i1.6309 J Dhaka Med Coll. 2009; 18(1) : 64-69