Infant Health Survey Research Articles

The effect of positive and negative health behavior during gestation on pregnancy outcome.

This study examined the effects of substance use (alcohol, tobacco and/or drugs (cocaine and/or marijuana)) and healthy maternal behavior (prenatal care, prenatal class, vitamins, regular exercise) during gestation on pregnancy outcome. Live births from the nationally representative 1988 National Maternal and Infant Health Survey were analyzed. Pregnancy outcomes (infant birth weight, weeks gestation, one and five minute Apgar scores, whether or not the infant was transferred to another hospital after delivery and whether or not the infant was rehospitalized) were studied in multiple linear regression and logistic regression models. The relationship of the interaction of substance use and healthy behaviors and outcome was studied in all models. It was found that women engaging in substance use while pregnant were less likely to engage in healthy behavior. However, in general, engaging in healthy behaviors had the largest positive effects on outcome for those women who engaged in multiple substance use while pregnant. Significant interactions between healthy and unhealthy behavior were found for birth weight, weeks gestation and five minute Apgar scores, indicating that engaging in positive health behavior may help moderate some of the deleterious consequences of substance use during pregnancy.

Home Apnea Monitoring and Sudden Infant Death Syndrome

Objective.To estimate the U.S. national prevalence of apnea monitor use by birth weight classification and to examine the relationship between the use of apnea monitors and the occurrence of Sudden Infant Death Syndrome (SIDS).Design and setting.Data obtained from the 1988 National Maternal and Infant Health Survey (NMIHS) were used. Prevalence estimates of apnea monitor use were obtained by weighting survey data, and the relationship between monitor use and SIDS was accomplished by a case–control analysis using SIDS deaths and live controls obtained from the NMIHS.Outcome measure.Weighted estimates of the prevalence of apnea monitor use and odds ratios for the odds of use of an apnea monitor among SIDS victims compared with the odds of use of an apnea monitor among living controls.Results.The national prevalence estimates for home apnea monitor use among birth weight strata of 500 to 1,499 g, 1,500 to 2,499 g, and 2,500 g or more for blacks were 19.9, 2.6, and 1.1% compared with 44.0, 8.8, and 1.2% for non-blacks. The only significant association between the use of apnea monitors and SIDS was for black 500- to 1,499-g infants. The adjusted odds ratio for SIDS among monitored black 500- to 1,499-g infants vs unmonitored infants was 3.93 (1.09, 14.17).Conclusions.This analysis suggests a marked difference in reported monitor use between U.S. black and non-black infants. In addition, black very low birth weight infants at highest risk for SIDS appear to be preferentially selected for monitoring.The protective effect of home apnea monitoring in this survey population is unclear.

Exercise, Employment, Other Daily Activities, and Adverse Pregnancy Outcomes

The relations of exercise, employment, and other daily activities during pregnancy with pregnancy outcomes were examined using data from the Missouri Maternal and Infant Health Survey. Maternal surveys were available for the following singleton birth categories: 450 fetal deaths; 782 very low birth weight (VLBW, or = 2,500 g). All mothers were Missouri residents at the time of their December 1989 to March 1991 deliveries. It was found that VLBW mothers had exercised during pregnancy significantly less than NBW mothers. When compared with NBW mothers before pregnancy, VLBW mothers had been just as likely not to exercise as NBW mothers (odds ratio (OR) = 0.88, 95% confidence interval (CI) 0.69-1.12). During the first, second, and third trimesters, the odds ratios decreased to 0.70 (95% CI 0.53-0.92), 0.54 (95% CI 0.40-0.74), and 0.33 (95% CI 0.20-0.53), respectively. The VLBW mothers also were less likely to exercise during the third trimester than MLBW mothers (OR = 0.34, 95% CI 0.21-0.54) or mothers with fetal deaths (OR = 0.36, 95% CI 0.19-0.67). During the 3 months after pregnancy, none of the exercise odds ratios were statistically significant between groups. No significantly increased risks were found between employment during pregnancy or other daily activities and adverse pregnancy outcome. The study supports the recently relaxed guidelines of exercise during pregnancy.

On the Validity of Using Census Geocode Characteristics to Proxy Individual Socioeconomic Characteristics

Abstract Investigators of social differentials in health outcomes commonly augment incomplete microdata by appending socioeconomic characteristics of residential areas (such as median income in a zip code) to proxy for individual characteristics. But little empirical attention has been paid to how well this aggregate information serves as a proxy for the individual characteristics of interest. We build on recent work addressing the biases inherent in proxies and consider two health-related examples within a statistical framework that illuminates the nature and sources of biases. Data from the Panel Study of Income Dynamics and the National Maternal and Infant Health Survey are linked to census data. We assess the validity of using the aggregate census information as a proxy for individual information when estimating main effects and when controlling for potential confounding between socioeconomic and sociodemographic factors in measures of general health status and infant mortality. We find a general, but...

Ethnicity and sources of prenatal care: findings from a national survey.

Improving pregnancy outcomes for minorities is a major goal of health providers and policy makers. Since most strategies involve an intervention during pregnancy, it is important to know where minority women with various characteristics receive prenatal care and why. Our purpose was to evaluate services of prenatal care for white, African-American, Mexican-American, and Puerto Rican women. The National Maternal and Infant Health Survey (1988) was used to ascertain age, income, marital status, education level, and source of funding of the study population of 21,000 women, who were assigned to an ethnic group based on self-indentification in the survey. The sources of prenatal care were classified as private (private physician, nurse-midwife, health maintenance organization) or public (state or local health department, community health center, hospital-based clinic). When categorized by ethnic group alone, 78 percent of white women received private care compared with 51 percent of Mexican-American women, 44 percent of African-American women, and 37 percent of Puerto Rican women. Private health insurance was held by 78 percent of white, 50 percent of African-American, 49 percent of Mexican-American, and 47 percent of Puerto Rican women. Of those with private insurance, 86, 62, 69, and 59 percent, respectively, received private care. Of white women with Medicaid funding, 52 percent received private care as opposed to a range of 20 to 42 percent for minority women. Substantial differences in sources of prenatal care exist between white and minority women and between different minority groups, suggesting that policy makers and health caregivers should tailor prenatal care intervention to the needs of specific minority populations.

Maternal occupation and pregnancy outcome.

Few studies have addressed the effect of maternal employment on late pregnancy outcomes. The National Maternal and Infant Health Survey, a probability sample of U.S. livebirths, stillbirths, and infant deaths in 1988, provided an opportunity to evaluate mothers' jobs in relation to preterm delivery, very low birthweight ( < 1,500 gm), moderately low birthweight (1,500-2,499 gm), small-for-gestational-age (SGA) birth, stillbirth, and infant death. We aggregated mothers' jobs, which were ascertained by mailed questionnaire or telephone interview, into categories for analysis. We considered jobs held at any time during pregnancy and jobs held during the fifth month of pregnancy. Relative to the referent group of clerks, textile workers had adjusted odds ratios of 1.5 or greater for all outcomes, with elevated risks also found sporadically for food service workers (preterm delivery, SGA birth, stillbirth) and electrical equipment operators (all outcomes except for still-birth and infant death). Janitors had elevated adjusted odds ratios of 2.0 or greater for preterm delivery and stillbirth. Relative to clerks, teachers and librarians tended to have reduced risks for adverse outcomes.

Breastfeeding among black mothers: evidence supporting the need for prenatal intervention.

To identify factors that might be targeted for intervention to increase breastfeeding among black mothers. Secondary analysis of the 1988 National Maternal Infant Health Survey. Black mothers (N = 5,142) from a nationally representative sample of mothers who had births in 1988. Breastfeeding rates Factors associated with breastfeeding included a mother's plan to breastfeed; Women, Infants and Children (WIC) advice, or advice from a prenatal-care provider on breastfeeding; and discussion of breastfeeding practices at prenatal birth classes. The results suggest that the prenatal period may be a critical time to influence a prospective black mother's decision to breastfeed her infant.

Preconceptional and prenatal multivitamin-mineral supplement use in the 1988 National Maternal and Infant Health Survey.

This paper examines the prevalence of multivitamin-mineral supplement use before and during pregnancy, as well as predictors of nonuse, in 9953 women who delivered live infants in the 1988 National Maternal and Infant Health Survey. Ninety-seven percent of the women were advised to take multivitamin-mineral supplements in prenatal care. Sixty-seven percent of Black mothers took supplements during pregnancy, as compared with 84% of White mothers. Multivariate analysis revealed that Black mothers; mothers who are less educated, younger, unmarried, and non-smokers; and mothers who participate in Women, Infants, and Children programs are at elevated risk for nonuse. These data help identify groups in need of supplementation guidance.

Exercise, Employment, Other Daily Activities, and Adverse Pregnancy Outcomes

The relations of exercise, employment, and other daily activities during pregnancy with pregnancy outcomes were examined using data from the Missouri Maternal and Infant Health Survey. Maternal surveys were available for the following singleton birth categories: 450 fetal deaths; 782 very low birth weight (VLBW, < 1,500 g); 802 moderately low birth weight (MLBW, 1,500-2,499 g); and 794 normal birth weight (NBW, > or = 2,500 g). All mothers were Missouri residents at the time of their December 1989 to March 1991 deliveries. It was found that VLBW mothers had exercised during pregnancy significantly less than NBW mothers. When compared with NBW mothers before pregnancy, VLBW mothers had been just as likely not to exercise as NBW mothers (odds ratio (OR) = 0.88, 95% confidence interval (CI) 0.69-1.12). During the first, second, and third trimesters, the odds ratios decreased to 0.70 (95% CI 0.53-0.92), 0.54 (95% CI 0.40-0.74), and 0.33 (95% CI 0.20-0.53), respectively. The VLBW mothers also were less likely to exercise during the third trimester than MLBW mothers (OR = 0.34, 95% CI 0.21-0.54) or mothers with fetal deaths (OR = 0.36, 95% CI 0.19-0.67). During the 3 months after pregnancy, none of the exercise odds ratios were statistically significant between groups. No significantly increased risks were found between employment during pregnancy or other daily activities and adverse pregnancy outcome. The study supports the recently relaxed guidelines of exercise during pregnancy.

Midwives, physicians, and the timing of maternal postpartum discharge

Hospitalization for childbirth has traditionally provided the opportunity to assure that infants and mothers have adjusted to the birth and that ongoing care has been arranged, but economic and social pressures have resulted in a dramatic decrease in the duration of hospitalization. Using a sample of mothers who delivered well infants from the 1988 nationally representative. National Maternal and Infant Health Survey, this study examines how midwives and physicians used an extra day of hospitalization in response to demographic, economic, behavioral, health status, and health care risk factors. Although midwives were much more likely to discharge mothers early (OR = 2.29) there were marked differences between risk factors and discharge timing for midwives and physicians. For the patients of midwives, the only factor associated with early discharge timing was attendance at childbirth classes. For the patients of physicians, less than a high school education, inadequate prenatal care, receipt of Medicaid or lack of insurance and no childbirth classes were associated with early discharge. In spite of the intense pressures to discharge patients early midwives appear to have been more attentive to potential risk factors in making discharge decisions in 1988. Because brief hospitalization is now prevalent, attention to maternal and newborn adjustment after birth, as apparently practiced by midwives, is crucial.

Breast-feeding in adolescent mothers: The National Maternal and Infant Health Survey, 1988

Breast-feeding in adolescent mothers: The National Maternal and Infant Health Survey, 1988

Exercise during pregnancy among US women

This report describes the prevalence and pattern of exercise during pregnancy among US women. It is based on 9953 randomly selected women who gave birth to live infants in 1988 and participated in the National Maternal and Infant Health Survey, a cross-sectional survey with a stratified systematic sampling in 48 states, the District of Columbia, and New York City. Self-reported exercise before and during pregnancy, specific activities, and number of months of exercise were examined in relation to maternal demographic characteristics, reproductive history, and prenatal care. Forty-two percent of all women reported exercising during pregnancy, half of whom exercised longer than 6 months. Walking was the leading activity (43% of all activities reported), followed by swimming (12%) and aerobics (12%). Older mothers and women who had multiple gestations, previous children, or an unfavorable reproductive history were less likely to exercise during pregnancy. Given this high prevalence of exercise in pregnancy, more research is warranted on both the beneficial and adverse maternal and fetal effects of exercise in pregnancy.

The intergenerational relationship between mother's birthweight, infant birthweight and infant mortality in black and white mothers.

The relationship between the birthweight of white and black mothers and the outcomes of their infants were examined using the 1988 National Maternal and Infant Health Survey. White and black women who were low birthweight themselves were at increased risk of delivering very low birthweight (VLBW), moderately low birthweight (MLBW), extremely preterm and small size for gestational age (SGA) infants. Adjustment for the confounding effects of prepregnant weight and height reduced the risks of all these outcomes slightly, and more substantially reduced the maternal birthweight associated risk of moderately low birthweight among white mothers. There was little effect of maternal birthweight on infant birthweight-specific infant mortality in white mothers; however, black mothers who weighed less than 4 lbs at birth were at significantly increased risk of delivering a normal birthweight infant who subsequently died. Although the risks for the various outcomes associated with low maternal birthweight were not consistently higher in black mothers compared with white mothers, adjustment for prepregnant weight and height had a greater effect in white mothers than in black mothers. We suggest that interventions to reduce the risks for adverse pregnancy outcomes associated with low maternal birthweight should attempt to optimise prepregnant weight and foster child health and growth.

Maternal Age and Labor Complications in Healthy Primigravidas at Term

The objective of this study was to describe the association between maternal age and selected risk indicators (both recognized and potential) to determine whether any were predictive of labor complications in women having a first child. Low-risk primigravidas (n = 1,792) were selected from a large national probability sample of births for 1988 (the National Maternal and Infant Health Survey). Recognized and potential risk indicators were described according to categories of maternal age and the occurrence of labor problems. Stratified analysis and logistic regression were used to assess the association of various risk factors with labor complications adjusted for maternal age. Only cesarean delivery varied significantly across maternal age groups, the rate being 11.6% for those < 20, 15.9% for those age 20–29, and 28.3% for those ⩾ 30. Cesarean delivery was associated with several characteristics of social advantage. Independent risk factors for cesarean delivery were maternal age (particularly ⩾ 30), epidural anesthesia, and receipt of adequate prenatal care. We conclude that older primigravidas have significantly more cesarean deliveries, and this is partially explained by characteristics of social advantage. To address the high cesarean rate, care providers need a better understanding of the relationship between social circumstances and cesarean delivery.

Examples of Differing Weighted and Unweighted Estimates from a Sample Survey

Abstract Unweighted estimators using data collected in a sample survey can be badly biased, whereas weighted estimators are approximately unbiased for population parameters. We present four examples using data from the 1988 National Maternal and Infant Health Survey to demonstrate that weighted and unweighted estimators can be quite different, and to show the underlying causes of such differences.

How Old Are U.S. Fathers?

One in every six U.S. birth certificates have no information on the age of the baby's father; for more than four in 10 babies born to adolescent women, no data are available on the father's age. Information from mothers aged 15-49 who had babies in 1988 and were surveyed in the National Maternal and Infant Health Survey indicates that fathers for whom age is not reported on the birth certificate are considerably younger than other fathers. In 1988, 5% of fathers were under age 20, and 20% were aged 20-24. Fathers typically are older than mothers, especially when the mothers are teenagers. Fathers who are unmarried, black or partners of lower income women are younger than other fathers.

Infant mortality in the United States: trends, differentials, and projections, 1950 through 2010.

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.

A reexamination of the risk factors for the sudden infant death syndrome

Objective: To determine which risk factors are specific for the sudden infant death syndrome (SIDS) rather than characteristic of postneonatal deaths in general. Study population: The live births and infant death cohorts of the 1988 National Maternal and Infant Health Survey. Methods: Information on live births, deaths from SIDS, and postneonatal deaths from other causes was abstracted from the National Maternal and Infant Health Survey. To account for oversampling of certain populations, the data were weighted to reflect national counts. Risk factors were defined as black race, birth weight less than 1500 gm, birth weight less than 2500 gm, gestational age at birth less than 37 weeks, 5-minute Apgar score less than 7, male gender, more than two previous pregnancies, maternal age less than 20 years, maternal education level less than 12 years, multiple births, and maternal smoking during pregnancy. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to compare the SIDS with the live births cohort, infants who died of other causes with the live births cohort, and SIDS with non-SIDS deaths. The population-attributable risk percentage was computed for risk factors independently associated with SIDS when compared with other postneonatal deaths. Results: For all characteristics other than a 5-minute Apgar score less than 7, the ORs comparing infants who died of SIDS with the live births cohort were significantly greater than 1.0. Similarly, ORs comparing infants who died of other causes with the live births cohort were also greater than 1.0, except for male gender. When the two infant death cohorts were compared, only maternal smoking during pregnancy and low maternal education level were significantly more common among the SIDS group. After we controlled for cigarette smoking, the adjusted OR for low maternal education level was not significantly greater than 1.0. However, even after control for low maternal education level, prenatal exposure to tobacco was significantly more common among the SIDS group than in infants dying of other causes (OR = 1.97; 95% CI, 1.59 to 2.45). On the basis of an adjusted OR of 2.92 when the SIDS group was compared with the live births cohort, the population-attributable risk percentage for maternal smoking as a risk factor for SIDS was 30%. Conclusion: Among characteristics generally thought to be risk factors, only maternal smoking during pregnancy was independently associated with SIDS. Data from this nationally representative sample indicate that if women refrained from smoking while pregnant, up to 30% of SIDS might be prevented. (J PEDIATR 1995;126:887-91)

An introduction to nonparametric regression in demographic research.

"My intent in this...paper is to alert demographers to the existence of useful new methods, known collectively as nonparametric (NP) regressions, that have been made possible by reductions in computing costs over the last several decades. NP regressions use brute force computing power to free researchers from the need to make strong a priori assumptions about functional forms, thus allowing greater flexibility and accuracy in modelling relationships than in standard parametric approaches. Increased flexibility and computing power do not eliminate the central role of theory in guiding social science research, but they free empirical analysis from the requirement that relationships between variables must have mathematically convenient shapes....I begin this paper with a discussion of bias-variance tradeoffs in regression models, followed by a discussion of localized regression. Subsequent sections discuss specific NP techniques for bivariate and multivariate regressions, with examples. Throughout this paper I will illustrate with data from 17,851 mothers aged 15-45 who were interviewed in the 1988 U.S. National Maternal and Infant Health Survey." (SUMMARY IN FRE)

What Predicts Breastfeeding Intention in Mexican‐American and Non‐Hispanic White Women? Evidence from a National Survey

We examined the effects of a series of predictors on the prepartum intention to breastfeed in both Mexican-American and non-Hispanic white women. A national sample included 430 Mexican-American women and 3659 non-Hispanic white women who had a pregnancy in 1988. Prenatal behavioral, sociodemographic, and biomedical information was obtained through the 1988 National Maternal and Infant Health Survey. Two dependent variables were constructed to identify significant predictors of breastfeeding intention: exclusive versus partial and bottle-feeding, and exclusive and partial versus bottle-feeding. Results from the multiple logistic regression models indicated that advice to breastfeed at prenatal care was the strongest predictor of intentions in both Mexican-American (OR = 2.15, OR = 1.86) and non-Hispanic white mothers (OR = 2.29, OR = 3.61). In Mexican-Americans the father's being Hispanic was negatively associated with breastfeeding intention (OR = 0.63). In non-Hispanic whites the advice to formula feed at the Women, Infants, and Children's nutrition program was a significant negative predictor of breastfeeding intention (OR = 0.33, for exclusive and partial breastfeeding vs exclusive bottle-feeding). These results have important implications for public health policy and practice.