National Maternal And Infant Health Survey Research Articles

Does Physical Activity During Pregnancy Reduce the Risk of Gestational Diabetes among Previously Inactive Women?

Gestational diabetes affects approximately 7 percent of all pregnancies in the United States; its prevalence may have increased among all ethnic groups since the early 1990 s. Our study examined whether physical activity during pregnancy reduced the risk of gestational diabetes among women who were physically inactive before pregnancy. We used data from the 1988 National Maternal and Infant Health Survey (NMIHS), a nationally representative sample of mothers with live births. The NMIHS obtained mothers' gestational diabetes diagnoses from care providers and mothers reported their physical activity before and during pregnancy, including the number of months with physical activity and types of physical activity. We developed a physical activity index, the product of the number of months with physical activity, and average metabolic equivalents for specific activities. The analysis included 4,813 women who reported being physically inactive before pregnancy, with singleton births and no previous diabetes diagnosis. Gestational diabetes was diagnosed in 3.5 percent of the weighted sample in 1988. About 11.8 percent of these previously inactive women began physical activity during pregnancy. Women who became physically active had 57 percent lower adjusted odds of developing gestational diabetes than those who remained inactive (OR 0.43, 95% CI 0.20-0.93). Women who had done brisk walking during pregnancy had a lower adjusted risk of gestational diabetes (OR 0.44, CI 0.19-1.02) and women with a physical activity index score above the median had 62 percent lower odds of developing gestational diabetes than the inactive women (CI 0.15-0.96). Results suggest that physical activity during pregnancy is associated with lower risk for gestational diabetes among previously inactive women.

The Impact of Having A Young Child with Disabilities on Maternal Labor Supply by Race and Marital Status

Data from the National Maternal and Infant Health Survey (NMIHS) with the three-year follow-up survey data were used to assess the impact of having a young child with disabilities on maternal labor supply. The oversampling of low birth-weight and African-American births in NMIHS provides a larger proportion of disabled children and a bigger sample of black mothers than available in data used in prior studies. The empirical analyses examined the impact of child disability on maternal employment participation and conditional intensity by race and marital status using alternative measures of disability based on occurrence of specific health conditions as well as activity performance and general development. Exogeneity of activity-based disability measures was tested using health conditions as instruments and instrumental variable models were used to estimate their impacts on maternal labor supply. The results indicated that activity-based measures are endogenous for black single and white married mothers. Model results suggested large reductions in likelihood of employment participation of black single as well as white single and married mothers. Work intensity of employed black single mothers was also substantially reduced by child disability. Overall, no consistent effects of child disability were observed for black married mothers.

Delivering A Very Low Birth Weight Infant and The Subsequent Risk of Divorce or Separation

The simultaneous rise over the last two decades in the U.S. in the proportion of VLBW (<1500 grams) deliveries and the improvement in their chance of survival has increased the number of families caring for VLBW infants and children. The families of VLBW infants with adverse outcomes can face psychological and monetary stresses, which in turn may influence marital instability and increase the risk of divorce or separation. The purpose of this paper is to identify the relationship of having a VLBW birth with the probability of divorce or separation in the first two years following delivery. We use data from the 1988 National Maternal and Infant Health Survey (NMIHS). This national stratified, systematic "follow-back" survey augments information from birth records in 1988 by obtaining information on social, demographic, and economic variables from women that delivered a baby in 1988. We estimate a proportional discrete time hazard model of transitions to divorce/separation. Parents of a VLBW infant have 2-fold higher odds of divorce/separation compared with parents of a child with a birth weight greater than 1500 grams. Two years after delivery of a non-VLBW baby 95 percent of the marriages remain stable, while about 90 percent of the marriages remain stable following the birth of a VLBW baby. If the pregnancy was not desired, then only 85 percent of the marriages remain stable 2 years following the delivery of a VLBW infant. There is an evident need to counsel and support families with VLBW infants on mechanisms to cope with the initial stressors that can be anticipated to arise.

Is prenatal care really ineffective? Or, is the ‘devil’ in the distribution?

Prenatal care should improve infant health, yet research frequently finds only weak effects. If there are two kinds of pregnancies, ‘complicated’ and ‘normal’ ones, then combining these pregnancies may lead prenatal care to appear ineffective. Data from the National Maternal and Infant Health Survey (NMIHS) offers compelling evidence. The standard 2SLS approach yields obviously bimodal residuals and frequently insignificant prenatal care coefficients. In contrast, estimating birth weights with a finite mixture model yields estimates revealing that prenatal care has a substantial effect on ‘normal’ pregnancies. Our Monte Carlo experiment confirms that ignoring even a small proportion of ‘complicated’ pregnancies can lead prenatal care to appear unimportant.

Breastfeeding and the risk of postneonatal death in the United States.

Breastfed infants in the United States have lower rates of morbidity, especially from infectious disease, but there are few contemporary studies in the developed world of the effect of breastfeeding on postneonatal mortality. We evaluated the effect of breastfeeding on postneonatal mortality in United States using 1988 National Maternal and Infant Health Survey (NMIHS) data. Nationally representative samples of 1204 infants who died between 28 days and 1 year from causes other than congenital anomaly or malignant tumor (cases of postneonatal death) and 7740 children who were still alive at 1 year (controls) were included. We calculated overall and cause-specific odds ratios for ever/never breastfeeding among all children, conducted race and birth weight-specific analyses, and looked for duration-response effects. Overall, children who were ever breastfed had 0.79 (95% confidence interval [CI]: 0.67-0.93) times the risk of never breastfed children for dying in the postneonatal period. Longer breastfeeding was associated with lower risk. Odds ratios by cause of death varied from 0.59 (95% CI: 0.38-0.94) for injuries to 0.84 (95% CI: 0.67-1.05) for sudden infant death syndrome. Breastfeeding is associated with a reduction in risk for postneonatal death. This large data set allowed robust estimates and control of confounding, but the effects of breast milk and breastfeeding cannot be separated completely from other characteristics of the mother and child. Assuming causality, however, promoting breastfeeding has the potential to save or delay approximately 720 postneonatal deaths in the United States each year.

Prepregnancy body mass index as a risk factor for stillbirth ≥28 weeks in the united states

BIRTH $28 WEEKS IN THE UNITED STATES SUSAN LASHLEY, CANDE ANANTH, WENDY KINZLER, JOHN SMULIAN, ANTHONY VINTZILEOS, UMDNJ–Robert Wood Johnson Medical School/Robert Wood Johnson University Hospital, Department of Obstetrics, Gynecology and Reproductive Sciences, New Brunswick, NJ OBJECTIVE: To determine if increased prepregnancy maternal body mass index (BMI) is an independent risk factor for stillbirth $28 weeks and to examine if the relationship is different among black and non-black women. STUDY DESIGN: We utilized the National Maternal and Infant Health Survey (NMIHS) data to examine the relationship between prepregnancy BMI (weight over squared-height) and stillbirth $28 weeks in singleton gestations. NMIHS data were collected in 1988 using sampling techniques that allow for extrapolation of the findings to the general U.S. population by weighted analyses. BMI (kg/m2) was categorized as underweight ( <20), normal weight (20-24.9), overweight (25-29.9), and obese ($30). Association between BMI and stillbirth risk was expressed as relative risk (RR) and 95% confidence interval (CI), derived from logistic regression models after adjusting for maternal age, nulliparity, education, marital status, smoking, diabetes mellitus, chronic hypertension, and preeclampsia. RESULTS: Of the 11,187 women in the sample (which corresponds to a weighted population of 3,673,130 women), the risks of stillbirth among black and non-black women were 5.4 (n = 5133) and 3.2 (n = 6054) per 1000 total births, respectively. The association (RR and 95% CI) between race-specific prepregnancy BMI and stillbirth is shown in the Table below. CONCLUSION:Our data indicate that obesity (BMI$30) is associated with an increased risk for stillbirth $28 weeks in both blacks and non-blacks. Although the risk of stillbirth was higher among blacks than non-blacks, the pattern of association between BMI and stillbirth risk were fairly similar between these race groups.

The effect of regular leisure physical activity on birth outcomes.

The purpose of this study was to determine the effect of regular leisure physical activity (RLPA) on two different adverse birth outcomes: timeliness of delivery (<37 weeks, preterm; 37-42 weeks, term; and >42 weeks, postterm) and low birth weight (<1500 g, very low; 1500-2499 g, low). The present sample, consisting of 9089 women, was obtained from the 1988 National Maternal and Infant Health Survey (NMIHS) data. The NMIHS was developed to examine adverse birth outcomes by assessing various maternal characteristics such as demographic, behavioral, and health care factors not found in vital statistics data. The specified adjusted models obtained by logistic regression indicate that women who failed to engage in RLPA before and during their pregnancy were more likely to give birth to a very low birth weight baby [OR = 1.75; 95% CI (1.50, 2.04)] but not to a low birth weight baby [OR = 1.15: 95% CI (0.99, 1.34)] compared with women who remained active before and during pregnancy. Moreover, previously active women who stopped physical activity during pregnancy were more likely to give birth to a low birth weight [OR = 1.28; 95% CI (1.05, 1.56)] or a very low birth weight [OR = 2.05; 95% CI (1.69, 2.48)] baby than women who remained active before and during pregnancy. There was no significant relationship between RLPA and timeliness of delivery. Similar results were found after controlling for maternal medical risk. RLPA during pregnancy had no deleterious effect on birth outcomes among these women. RLPA may also reduce the risk of low birth weight outcomes.

Content of Prenatal Care and Spontaneous Preterm Birth

The purpose of this study was to examine the relationship between selected components of the content of prenatal care and spontaneous preterm birth, based on analyses of the 1988 National Maternal and Infant Health Survey (NMIHS) conducted by the National Centers for Health Statistics (NCHS, USA). Spontaneous preterm birth was subcategorized into very preterm and moderately preterm births, with term birth as the controls. This study concluded that there were differences in selected components of the content of prenatal care between the cases and controls, overall and stratified by ethnicity, but they were confounded with missing values and associated preterm delivery bias. There were differences in selected components of the content of prenatal care between Anglo- and African-American cases, but they were difficult to interpret definitively due to item non-response and preterm delivery bias. In addition, no significant predictive association between selected components of the content of prenatal care and spontaneous preterm birth was found. However, inadequate/intermediate prenatal care and birth out of wedlock were found to be associated with moderately preterm birth.

The Effect of Substance Use in Pregnancy on the Risk of Infant Mortality

Using data from the 1988 National Maternal and Infant Health Survey (NMIHS), this study examined the effect of maternal substance use during pregnancy on infant mortality in the United States. Logistic regression models were fitted to a 1988 cohort of births to study infant deaths. The results of the logistic regression models indicated that cigarette smoking and cocaine / crack use were associated with significantly higher risk of infant death. Mothers who smoked 1–19 cigarettes per day while pregnant were 38 percent more likely to experience infant mortality than nonsmokers. Heavy users of cocaine / crack were over twice as likely to have infant death as nonusers. Light cocaine users experienced a risk of infant mortality that was over three times that of nonusers. In general, alcohol consumption and marijuana / hash use in pregnancy had no significant effects on infant mortality. Analysis showed that while birth weight is the primary pathway by which cigarettes and cocaine / crack increase the risk of death, the two substances also affect mortality directly. It was concluded that while self-reports of substance use in the National Maternal and Infant Health Survey may to some extent be unreliable, the findings indicate that the true extent of substance use in pregnancy is underestimated. Relatedly, the finding of statistical significance on substance use despite the high rate of nonresponse illustrates that these substances have far more devastating consequences on infant mortality than those estimated in the analysis.

Maternal substance use during pregnancy and developmental outcome at age three.

The data from the National Maternal and Infant Health Survey (NMIHS) and its 3-year follow-up offer a unique opportunity to study the effects of substance (alcohol, marijuana, and tobacco) use during gestation on development at age three in a nationally representative sample. Using this data, the relationship of development (language, gross motor, fine motor, and adaptive behavior) and specific behaviors (eating problems, length of play, activity level, difficulty of management, level of happiness, fearfulness, ability to get along with peers, tantrums, eating nonfood) and maternal drinking, marijuana use, and cigarette smoking was studied in a sample of live births who had been followed up at age three. The data were analyzed using a cumulative logit model of ordinal responses. Higher activity level, greater difficulty of management, tantrums, eating problems, and eating nonfood were related to maternal drinking during pregnancy. Increased fearfulness, poorer motor skills, and shorter length of play were associated with maternal marijuana use during pregnancy. Less well developed language, higher activity level, greater difficulty of management, fearfulness, decreased ability to get along with peers, and increased tantrums were associated with maternal cigarette smoking during pregnancy. The preponderance of significant effects involved the behaviors studied rather than the developmental indices. It may be that the effects of substance use during pregnancy, especially more subtle ones, show up in behavior before they can be measured by developmental scales.

Maternal depressive symptoms and child behavior problems in a nationally representative normal birthweight sample.

To evaluate the association between maternal depressive symptoms and child behavior problems in a nationally representative sample of U.S. mothers of normal birthweight babies. We analyzed data from the 1988 National Maternal and Infant Health Survey (NMIHS) and a 1991 follow-up survey. Depressive symptoms were measured at both surveys using the CES-D, and child behavior problems were assessed by maternal self-report at follow-up. Approximately 28% of the 5303 mothers reported depressive symptoms at a mean of 17 months after delivery, as did 20% at 36 months. In multivariate analyses, women with depressive symptoms at either or both surveys were significantly more likely than women without depressive symptoms to report that their children had frequent temper tantrums or difficulty getting along with other children, and were difficult to manage, unhappy, or fearful. Compared to women without depressive symptoms, the risks of reporting three out of the five child behavior problems for women with depressive symptoms were OR = 1.6 (CI = 1.1-2.1), 1988 only; OR = 2.3 (CI = 1.6-3.3), 1991 only; and OR = 3.6 (2.6-5.0), both 1988 and 1991. Study findings indicate that a substantial proportion of mothers of young children in the United States experience depressive symptoms and that their children are at significantly increased risk of maternally reported behavior problems. Our results suggest that efforts to identify and treat depression in new mothers should be increased and that mothers whose children are found to have behavior problems should be assessed for depression.

Alcohol use prior to pregnancy recognition

Background: Frequent alcohol use during the first 8 weeks of pregnancy can result in spontaneous abortion and dysmorphologic changes in the developing organ systems of the embryo, including the heart, kidneys, and brain. However, few population-based studies are available that describe the prevalence of frequent drinking (6 or more drinks per week) among women prior to and during early pregnancy (the periconceptional period), and the sociodemographic and behavioral factors that characterize these women. Such knowledge is fundamental to the design of targeted interventions for the prevention of fetal alcohol syndrome (FAS) and other prenatal alcohol-related disorders. Methods: This cross-sectional study used survey data collected by the National Center for Health Statistics as part of the 1988 National Maternal and Infant Health Survey (NMIHS). Weighted prevalence estimates were calculated using SUDAAN, and multivariate analyses were used to determine risk factors for frequent drinking. Results: Forty-five percent of all women surveyed reported consuming alcohol during the 3 months before finding out they were pregnant, and 5% reported consuming 6 or more drinks per week. Sixty percent of women who reported alcohol consumption also reported that they did not learn they were pregnant until after the fourth week of gestation. Risk factors for frequent drinking during the periconceptional period included 1 or more of the following: being unmarried, being a smoker, being white non-Hispanic, being 25 years of age or older, or being college educated. Conclusions: Half of all pregnant women in this study drank alcohol during the 3 months preceding pregnancy recognition , with 1 in 20 drinking at moderate to heavy levels. The majority did not know they were pregnant until after the fourth week of pregnancy, and many did not know until after the 6th week. Alcohol is a teratogen capable of producing a number of adverse reproductive and infant outcomes. Public health measures needed to reduce these potentially harmful exposures include alcohol assessment , education, and counseling for women of childbearing age, with referral sources for problem drinking, and family planning services for pregnancy postponement until problem drinking is resolved.

Risk of previous very low birth weight and very preterm infants among women delivering a very low birth weight and very preterm infant.

To examine the relationship of the birth of a very low birth weight (VLBW, < 1500 gm) and very preterm (VPT, < or = 32 week) infant to previous occurrences of VLBW-VPT infants among women who had two to five pregnancies. This was a case-control study using data from the 1988 National Maternal and Infant Health Survey (NMIHS). A case was defined as a singleton live birth weighing 500 to 1499 gm with a gestational age of < or = 32 weeks. Control infants were defined as singleton births weighing > 2500 gm with gestational ages of > or = 38 weeks. There were 128 non-black cases and 864 non-black controls, and 241 black cases and 1205 black controls available for analysis. Logistic regression was used to adjust for a history of previous stillbirth, mother's birth weight, pre-pregnancy weight, pregnancy interval, and sociodemographic risk factors. The adjusted odds ratio for the occurrence of a previous VLBW-VPT birth for non-black cases versus controls was 21.24 (6.87, 65.7) and for black cases versus controls, 6.87 (3.82, 12.34). These results confirm the substantial risk of previous VLBW-VPT infants among women giving birth to such an infant, independent of sociodemographic factors and other prior pregnancy outcomes.

Newborn Primary Care Visit Patterns Identify Mothers with Postpartum Depressive Symptoms • 535

Background. We previously reported results of a prospective cohort study showing that women whose infants have emergency department visits or frequent problem-oriented primary care visits (PPCV) in the first 3 weeks of life are significantly more likely to exhibit depressive symptoms at 8 weeks postpartum. Objective. To validate our previous findings using a nationally representative sample, specifically testing whether women whose neonates have frequent PPCV have increased risk of postpartum depressive symptoms. Methods. Design. Secondary analysis of the 1988 National Maternal and Infant Health Survey (NMIHS), an interview survey of a nationally representative sample of women who had live births in 1988, conducted by the National Center for Health Statistics. Subjects. NMIHS women who had full term, live singleton births. Measures. Independent measure was >1 PPCV. Depressive symptoms were assessed by the Center for Epidemiologic Studies depression scale (CES-D). The dependent variable was CES-D≥16 (women with incomplete responses to the CES-D were excluded). Covariates were maternal age, race, Hispanic ethnicity, parity, educational level, income, and payor status. Analysis. Weighted percentages were calculated for univariate analyses. Multivariate analyses were adjusted for design effects using SUDAAN. Results. There were 6779 women in the sample. 7.1% of babies had >1 PPCV and 13.2% had >1 well child visit (WCV) in the first month postpartum. 23.1% of mothers had depressive symptoms. Before and after adjustment for covariates, women whose infants had>1 PPCV within the first month of life were more likely to be depressed(Adj OR 2.04, 95%CI 1.45-2.94, p 1 WCV within the first month were no more likely have depressive symptoms (Adj OR 1.11, 95%CI 0.83-1.49, p=0.47). Conclusion. Women whose infants have frequent PPCV, but not WCV, are more likely to exhibit depressive sympoms. Whether depression is the basis or the result of these infant outpatient visit patterns, the risk groups identified need close monitoring. Referral of mothers by pediatric health providers recognizing these patterns may facilitate early diagnosis and treatment of postpartum depression, thereby improving oucomes for women and their families.

Can Regular Multivitamin/Mineral Supplementation Modify the Relation between Maternal Smoking and Select Adverse Birth Outcomes?

PURPOSE: The purpose of this study was to examine whether or not regular multivitamin/mineral supplementation can modify the relation between maternal smoking and preterm birth (gestational age < 37 weeks), very-low-birthweight (VLBW) (< 1500 g), moderately-low-birthweight (MLBW) (< 2499 g), or small-for-gestational-age (SGA) (< 10th percentile of birth weight for gestational age).METHODS: Live birth data from the 1988 National Maternal and Infant Health Survey (NMIHS) were used for the analysis. Maternal smoking referred to self-reported average number of cigarettes smoked after recognition of pregnancy, while regular multivitamin/mineral supplementation referred to use of multivitamin/mineral supplements for at least three days per week during the three months before and/or after recognition of pregnancy. Sample sizes included 9402 singleton infants for the analysis of preterm birth, 9395 for very or moderately low birthweight, and 9363 for small-for-gestational-age. Odds ratios were derived from logistic regression analyses after adjusting for a number of demographic and reproductive variables.RESULTS: Major results include: 1) increased risks for the adverse outcomes studied were observed among smoking women; 2) no effect of regular multivitamin/mineral supplementation in the absence of maternal smoking was revealed; and 3) relative excess risks due to interaction at different smoking levels and overall interactions between smoking and supplementation were not observed.CONCLUSIONS: These results suggest that regular multivitamin/mineral supplementation does not minimize the adverse effects associated with maternal smoking.

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.

Sociodemographic and Behavioral Characteristics Associated With Alcohol Consumption During Pregnancy—United States, 1988

Identification of women at risk for consuming alcohol during pregnancy is critical to the design of interventions for reducing the adverse effects of alcohol on both women and their children. This report uses data from the 1988 National Maternal and Infant Health Survey (NMIHS)--the most recent vital records survey for which a population-based sample of this size was available--conducted by CDC's National Center for Health Statistics to analyze characteristics of women who drink alcohol during pregnancy.