Relationship of passive cigarette-smoking to sudden infant death syndrome

The smoking habits of 56 families who lost babies to the sudden infant death syndrome (SIDS) were compared to those of 86 control families. A higher proportion of SIDS mothers smoked both during pregnancy (61% vs. 42%) and after their babies were born (59% vs. 37%). SIDS mother also smoked a significantly greater number of cigarettes than controls. Exposure to cigarette smoke ("passive smoking") appears to enhance the risk of SIDS for reasons not known.     

The unreamed AO femoral intramedullary nail, advantages and disadvantages of a new modular interlocking system. A prospective study of 67 cases

The aim of this study was to investigate associations between sudden infant death syndrome (SIDS) and social factors in the Nordic countries. A case-control study was conducted in Denmark, Norway and Sweden: The Nordic Epidemiological SIDS Study. Parents of 244 SIDS infants and 869 control infants matched on gender, age at death and place of birth filled in questionnaires. The dataset was analysed by conditional logistic regression. In univariate analysis, the following sociodemographic factors were associated with an increased risk of SIDS: low maternal age [odds ratio (OR) 7.8; 2.8-21.5], high birth order (OR 4.4; 2.5-7.5), single motherhood (OR 2.9; 1.7-5.0), low maternal education (OR 4.5; 2.8-7.1), low paternal education (OR 3.0; 1.9-4.7), maternal unemployment (OR 2.4; 1.8-3.4) and paternal unemployment (OR 4.0; 2.7-5.9). In a multivariate analysis where maternal smoking was also included, only paternal unemployment, young maternal age and high birth order remained significantly associated with SIDS. Housing conditions were not associated with SIDS. However, the risk of SIDS was high if the family had lived in their present home for only a few years (OR 2.3; 1.3-4.1). Sociodemographic differences remain a major concern in SIDS in a low-incidence situation and even in an affluent population with adequate health services.     

Placental transfer of maternal poliovirus antibodies in full-term and pre-term infants

This study was designed to investigate the placental transfer of maternal poliovirus antibodies in full-term and pre-term infants. Two hundred healthy, Israeli born mothers and their infants, were enrolled immediately after birth. The study population comprised two groups: a full-term group of 150 mothers and their infants, and a pre-term group of 50 mothers and their infants (gestational age < 35 weeks). Maternal and umbilical cord blood samples were taken in all cases. Antibody titers against the three poliovirus serotypes and a polio virus type 1 strain that caused an outbreak in 1988 (epidemic strain 1) were measured by a microneutralization system. The proportion of individuals with protective titers against each of the poliovirus types tested was slightly lower in the infants compared with their mothers. When protection to all strains combined was tested, the difference between mothers and infants was significant (P < 0.05). Transplacental transfer to epidemic strain 1 was less effective--12% of the premature infants were not protected against it at birth. The geometric mean titers against poliovirus types 1, 3 and epidemic type 1 strain were significantly lower in the pre-term group than in the full-term group. In both the full-term and pre-term groups there were significant linear correlations between the maternal and neonatal antibody titers for each of the polio viruses tested. For all poliovirus types, the transfer of maternal antibodies to the full-term infant was significantly higher than the transfer of maternal antibodies to the pre-term infant (P < 0.001). Owing to diminished transfer of maternal antibodies, pre-term infants are at greater risk of poliovirus infection.     

Sudden infant death syndrome: risk factor profiles for distinct subgroups

The authors investigated risk profiles of sudden infant death syndrome (SIDS) as a function of age at death. A case-control study carried out in the Tyrol region of Austria enrolled 99 infants who died of SIDS between 1984 and 1994 and 136 randomly selected controls. Early and late SIDS (< 120 days of age vs. > or = 120 days) were defined according to the clear-cut bimodal age-at-death distribution. Inadequate antenatal care, low parental social and educational level, and the prone sleeping position were risk conditions that applied to both early and late SIDS. A marked seasonal variation (winter preponderance) was the most outstanding feature of late SIDS. A gestational age of < 37 weeks (odds ratio (OR) = 8.4, 95% confidence interval (CI) 2.6-26.0), repeated episodes of apnea (OR = 5.7, 95% CI 1.2-27.0), low birth weight (< 2,500 g) (OR = 3.4, 95% CI 1.1-11.0), a family history of sudden infant death (OR = 2.9, 95% CI 1.1-7.5), and maternal smoking during pregnancy (OR = 2.2, 95% CI 1.0-4.5) were associated with early SIDS. This study identified two distinct subgroups of SIDS infants characterized by different risk conditions and ages at death. These results underline a multiple-cause hypothesis for SIDS etiology which involves a genetic predisposition, immaturity in the first months of life, and environmental factors acting at various ages.     

Fetal thrombocytopenia and its relation to maternal thrombocytopenia

BACKGROUND: Neonates with severe thrombocytopenia can have bleeding leading to death or lifelong residual defects. The predictors, frequency, and consequences of fetal thrombocytopenia are not known, nor is it known if there are maternal clinical features that could predict fetal thrombocytopenia. METHODS: We conducted a seven-year cross-sectional study in which platelet counts were determined in newborns' umbilical-cord blood and blood obtained from their mothers at consecutive deliveries in one obstetrical unit. The relations of the umbilical-cord platelet count to maternal risk factors were determined. RESULTS: Platelet counts were determined in blood samples from 15,471 mothers and 15,932 newborn infants. The cord-blood platelet count was less than 50,000 per cubic millimeter in 19 infants (0.12 percent; 95 percent confidence interval, 0.07 to 0.19 percent), whereas the platelet count was less than 150,000 per cubic millimeter in 6.6 percent of the mothers (95 percent confidence interval, 6.2 to 7.0 percent). One infant among those born to 756 mothers with incidental thrombocytopenia, 5 infants among those born to 1414 mothers with hypertension, and 4 infants among those born to 46 mothers with idiopathic thrombocytopenic purpura had cord-blood platelet counts between 20,000 and 50,000 per cubic millimeter. Only 6 infants (0.04 percent; 95 percent confidence interval, 0.01 to 0.08 percent) had cord-blood platelet counts of less than 20,000 per cubic millimeter; all their mothers were among the 18 whose 19 fetuses were at risk for neonatal alloimmune thrombocytopenia. Two of these infants had in utero intracranial hemorrhage. In addition, 3 infants born to these 18 women had cord-blood platelet counts between 20,000 and 50,000 per cubic millimeter; there was 1 stillbirth due to intracranial hemorrhage. CONCLUSIONS: Moderate-to-severe fetal thrombocytopenia is a rare event. The only severely affected neonates with morbidity or mortality due to this condition are those born to mothers with antiplatelet alloantibodies.     

Brainstem 3H-nicotine receptor binding in the sudden infant death syndrome

Maternal cigarette smoking during pregnancy has been shown to be a major risk factor for the sudden infant death syndrome (SIDS). We hypothesized that SIDS is associated with altered 3H-nicotine binding to nicotinic receptors in brainstem nuclei related to cardiorespiratory control and/or arousal. We analyzed 3H-nicotine binding in 14 regions in SIDS and control brainstems using quantitative tissue receptor autoradiography. Three groups were analyzed: SIDS (n = 42), acute controls (n = 15), and a chronic group with oxygenation disorders (n = 18). The arcuate nucleus, postulated to be important in cardiorespiratory control and abnormal in at least some SIDS victims, contained binding below the assay detection limits in all (SIDS and control) cases. We found no significant differences among the 3 groups in mean 3H-nicotine binding in the 14 brainstem sites analyzed. When a subset of the cases were stratified by the history of the presence or absence of maternal cigarette smoking during pregnancy, however, we found that there was no expected increase (upregulation) of nicotinic receptor binding in SIDS cases exposed to cigarette smoke in utero in 3 nuclei related to arousal or cardiorespiratory control. This finding raises the possibility that altered development of nicotinic receptors in brainstem cardiorespiratory and/or arousal circuits put at least some infants, i.e. those exposed to cigarette smoke in utero, at risk for SIDS, and underscores the need for further research into brainstem nicotinic receptors in SIDS in which detailed correlations with smoking history can be made.     

A record-linkage study on risk factors for cause-specific infant mortality

Infant death certificates were linked with birth certificates for infants born to residents of Tohoku, Tokai and Kyushu regions in 1989 (n = 409, 679, or about one-third of all births in Japan), to examine the effects of variables, as reported on birth certificates, on cause-specific infant mortality. "Certain conditions originating in the perinatal period" and "congenital anomalies" accounted for nearly 90 percent of neonatal deaths, while "congenital anomalies", "injuries and poisoning" and "sudden infant death" were responsible for about 65 percent of postneonatal deaths. Mortality rates for almost all causes of infant deaths, except injuries and poisonings, increased as birth weight decreased not only in the neonatal period but also in the postneonatal period. This suggests that low birth weight places some infants at higher risk of death, and conditions that lead to low birth weight independently contribute to the risk of infant death. Cox's proportional hazards linear model was used to assess the effects of variables on infant mortalities by causes of death. An extremely strong birth weight effect was noted for "certain conditions originating in the perinatal period" and "congenital anomalies". Being a male infant and late order of birth in multiparity were other risk factors for deaths from "congenital anomalies", while being a male infant, resident of Tohoku region and maternal stillbirth experience related to deaths from "certain conditions originating in the perinatal period". Elevated risks of sudden infant death syndrome (SIDS), of which mortality rate in Japan was considerably lower than those in most developed Western countries, i.e. 0.23 per 1,000 live births in 1989, were associated with low birth weight, being a male infant, low maternal age, late order of birth in multiparity and illegitimacy. Low maternal age, late order of birth in multiparity and illegitimacy, also, related significantly to increased risk of infant deaths for "injuries and poisoning". These results suggest the independent contributions of socioeconomic factors to infant mortality, especially postneonatal mortality, from SIDS, "injuries and poisonings".     

Maternal hypertension and neurodevelopmental outcome in very preterm infants

AIM: To determine the outcome of preterm infants born to mothers with hypertension during pregnancy, and preterm controls. METHODS: 107 infants of 24-32 weeks gestation, born to hypertensive mothers, and 107 controls matched for gestational age, sex, and multiple pregnancy, born to normotensive mothers, were prospectively enrolled over 2 years. Information on maternal complications and medication was obtained and neonatal mortality and morbidities recorded. Survivors were followed up to at least 2 years, corrected for prematurity. RESULTS: One third of the hypertensive mothers were treated with antihypertensive drugs, while 18% received convulsion prophylaxis with phenytoin. Magnesium sulphate was not prescribed. Both groups had a mean gestational age of 29.9 weeks, with the study infants having a significantly lower birthweight than the controls. Four study and three control infants died in the neonatal period. Cerebral palsy was not diagnosed in any infant of a hypertensive mother compared with five of the controls. The mean general quotient for the two groups was very similar and no difference in the incidence of minor neuromotor developmental problems was shown. CONCLUSIONS: Maternal hypertension seems to protect against cerebral palsy in preterm infants without increasing the risk of cognitive impairment. This was independent of the use of maternally administered magnesium sulphate.     

Neonatal polycythemia in appropriately grown infants of hypertensive mothers

Neonatal polycythemia is a frequent finding after pregnancies complicated by diabetes and by maternal hypertension with intrauterine growth retardation (IUGR). It is still unclear if the association of polycythemia with hypertension is the result of IUGR or of hypertension per se. To establish the incidence of neonatal polycythemia in populations at risk, we analyzed the results of hematocrit values obtained from 1592 neonates born consecutively at the Hospital de Clinicas, Buenos Aires. Capillary hematocrit values were obtained by heel stick before 6 h of age. When the values were 65% or greater, new samples were obtained from an antecubital vein. The risk of polycythemia in appropriately grown infants of hypertensive mothers was 12.6-fold greater than the risk in the general population. These data show that maternal hypertension poses a significant risk for polycythemia, regardless of fetal growth. We suggest that, to prevent possible sequela, hematocrit is measured routinely in all infants of hypertensive mothers for prompt diagnosis and treatment.     

Responsive parenting: Establishing early foundations for social, communication, and independent problem-solving skills.

Mothers whose infants varied in early biological characteristics (born at term, n = 120; born at very low birth weight [VLBW], n = 144) were randomized to a target group (n = 133) or developmental feedback comparison group (n = 131) to determine whether learning responsive behaviors would facilitate infant development. The target condition included videotaped examples, problem-solving activities, and mothers' critique of their own behaviors through video procedures across 10 home visits. All target versus comparison mothers showed greater increases across multiple responsiveness behaviors observed in 4 assessments conducted across 6-13 months of age; changes in emotionally supportive behaviors were strongest for target mothers of infants born at VLBW. Increased maternal responsiveness facilitated greater growth in target infants' social, emotional, communication, and cognitive competence, supporting a causal role for responsiveness on infant development. Although benefits were generally comparable across risk groups, aspects of social and emotional skills showed greater change for those born at VLBW. Evidence for responsiveness as a multidimensional construct was provided as well as the importance of different aspects of responsiveness mediating the effect of the intervention on different infant skill domains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neonatal death after induced abortion

An obstetrical practice based at a university hospital in Jerusalem has studied the offspring of 9,894 women who were pregnant at least once during the years 1966 through 1968, and discovered that the neonatal mortality rate was 2 to 3 times higher in infants born to women who reported a previous induced abortion. Among the women studied, 7.2% reported at least 1 previous abortion; immigrants from South Africa tended to have the highest rate of abortion, whereas the lowest rate was observed in the Arab population. An inverse relationship was detected between a history of induced abortion and the following: the degree of religious observance; maternal age at the time of marriage; and maternal age at the time of past deliveries. A positive correlation was observed between a history of induced abortion and the present age of the mother; smoking; Caesarian section; bleeding during pregnancy; vomiting during pregnancy; and the use of medications during the 1st trimester of the present pregnancy. The women in this study delivered a total of 11,057 infants between 1966 and 1968; infants born to mothers who reported a previous induced abortion experienced a higher neonatal mortality rate and were more likely to be low birth-weight infants, when compared to the group of infants whose mothers did not report a previous induced abortion.     

Effect of maternal cigarette smoking on pregnancy complications and sudden infant death syndrome

BACKGROUND: The purpose of this study was to estimate the annual morbidity and mortality among fetuses and infants that can be attributed to the use of tobacco products by pregnant women. METHODS: Published research reports identified by literature review were combined in a series of meta-analyses to compute pooled risk ratios, which, in turn, were used to determine the population attributable risk. RESULTS: Each year, use of tobacco products is responsible for an estimated 19,000 to 141,000 tobacco-induced abortions, 32,000 to 61,000 infants born with low birthweight, and 14,000 to 26,000 infants who require admission to neonatal intensive care units. Tobacco use is also annually responsible for an estimated 1900 to 4800 infant deaths resulting from perinatal disorders, and 1200 to 2200 deaths from sudden infant death syndrome (SIDS). CONCLUSIONS: Tobacco use is an important preventable cause of abortions, low birthweight, and deaths from perinatal disorders and SIDS. All pregnant women should be advised that smoking places their unborn children in danger. The low success rate of smoking cessation among pregnant women suggests that efforts to reduce the complications of pregnancy attributable to tobacco use by pregnant women should focus on preventing nicotine addiction among teenaged girls.     

Infants entering foster care compared to other infants using birth status indicators

OBJECTIVE: Infants comprise nearly one fourth of all entries to foster care. Linkage of administrative birth and placement data can provide information about these infants that may otherwise be unavailable or difficult to obtain. METHOD: Statewide birth records and foster care placement histories were linked via probability matching. Logit regression was used to compare 26,460 maltreated infants who entered foster care between 1989 and 1994 with a random sample of 68,401 other infants born during that time frame. RESULTS: Infants in care were more than twice as likely to have single parents and be born with low birthweight, and twice as likely to have been born with a birth abnormality as other infants, controlling for other factors. The largest difference was in the eightfold increased likelihood for mothers of infants in care to have had no prenatal care. Infants in care were nearly three times as likely to be born into larger families (third or greater live births to the mother). Mothers of infants in care were more than twice as likely to be African American compared to White than mothers of other infants, while Hispanic and Other ethnic groups were underrepresented in the group of infants in care. Foreign born mothers, especially Hispanic women, were much less likely to have infants in care than they were to have children in the other group. CONCLUSIONS: Administrative datasets, while often limited in the number of variables they include and scope of their information, can be a valuable tool when used to understand demographics and frame questions for future research. Infants who enter foster care differ in substantial ways from other children. These findings have important implications for future research aimed toward targeting of child welfare services and supports.     

Sleeping position, orientation, and proximity in bedsharing infants and mothers

The impact of mother-infant bedsharing on infant sleeping position, orientation, and proximity to the mother was assessed in 12 breast-feeding Latino mother-infant pairs. Six routinely bedsharing and six routinely solitary-sleeping pairs slept 3 nights in the sleep laboratory. The first night matched the routine home condition, followed by 1 bedsharing night and 1 solitary-sleeping night in random order. During bedsharing infants were never placed prone, regardless of their routine sleeping condition. On the bedsharing night, mothers and infants spent most of the night oriented toward each other; seven of 12 infants remained oriented toward their mothers the entire night. While sleeping in a face-to-face orientation, most pairs slept most of the time less than 30 cm apart with appreciable amounts of time at less than 20 cm. This orientation and proximity should facilitate sensory exchanges between mother and infant which, we hypothesize, influence the infant's sleep physiology and nocturnal behavior. We conclude that bedsharing minimizes the use of the prone infant sleeping position, probably in part to facilitate breast feeding. By promoting nonprone positions, bedsharing may protect some infants from sudden infant death syndrome (SIDS), since prone sleeping is a known risk factor for SIDS. The large percentage of the night that mothers spent oriented toward their infants suggests that a higher degree of maternal vigilance may also result from bedsharing.     

Multicenter comparison of first- and second-generation IMx tacrolimus microparticle enzyme immunoassays in liver and kidney transplantation

Foetuses born to mothers with gestational diabetes are at increased risk of developing respiratory distress, foetal macrosomia, foetal anomalies and platelet hyperaggregability. High blood glucose level induces oxidative stress and decreases antioxidant defences. The present study discusses the possibility of lipid peroxidation and protein oxidation in both maternal and foetal erythrocytes as an indicator of oxygen radical activity. The level of lipid peroxidation and protein oxidation in erythrocytes was estimated in 20 mothers with gestational diabetes and their newborns. The maternal age varied between 19 and 42 y and foetal age ranged between 34 and 39 weeks. The proteolytic activities in the erythrocyte lysates obtained from mothers with gestational diabetes and their newborns were significantly greater [(mean +/- SD) 24.41 +/- 9.05 and 16.70 +/- 3.36 microM of amino groups/g haemoglobin, n = 20, respectively] than those from control group (10.18 +/- 4.84 and 14.64 +/- 6.21 microM amino groups/g haemoglobin, n = 15, respectively; p < 0.05 in both cases). Similarly erythrocyte malondialdehyde levels were significantly elevated in babies born to mothers with gestational diabetes (10.11 +/- 2.21 nM/g haemoglobin) when compared to controls (6.8 +/- 3.75 nM/g haemoglobin) (p < 0.05). In the erythrocytes of mothers with gestational diabetes, malondialdehyde levels correlated significantly with glycated haemoglobin levels (p < 0.01). The results of this study indicate that the oxidative stress induced by gestational diabetes manifests as increased lipid peroxidation and protein oxidative damage in the erythrocytes of both mothers with gestational diabetes and their newborn infants.     

Recombinant human phenylethanolamine N-methyltransferase: overproduction in Escherichia coli, purification, and characterization

We studied major malformations in 5,581 infants with Down syndrome (DS) from three registers of congenital malformations. THe prevalence at birth of 23 different malformations was compared with the program-specific rates for each malformation in non-DS infants. An about 300 times risk increase was seen for annular pancreas, cataracts and duodenal atresia and an about 100 times risk increase for megacolon and small choanal atresia. Esophageal, anal and small bowel atresia, preaxial polydactyly, and omphalocele all showed risk increases between 10 and 30 times. Statistically significantly elevated risk ratios around 3-5 were seen for cleft palate, cleft lip/palate, and limb deficiencies. No increased risk was seen for neural tube defects, hydrocephaly, microtia, renal agenesis or severe dysgenesis, hypospadias or polydactyly other than preaxial. Oral clefts were more often present in DS in the Swedish material than in the other two materials. Cardiac defects were registered in 26% of all cases (varying between programs) but 28% of the cardiac defects were unspecified. DS infants born to women younger than 25 years had a significantly increased risk for megacolon and there was a trend increasing risk for esophageal or anal atresia with maternal age. A decreased risk for cardiac defect in DS infants born to teenage mothers was found, quite pronounced for endocardial cushion defects and ventricular septum defects. There were no statistically significant differences in the sex distribution of specific malformations in infants with DS and in non-DS infants.     

The risk of teen mothers having low birth weight babies: implications of recent medical research for school health personnel

This article reviews recent medical research on the relationship between young maternal age and the incidence of low birth weight infants. One line of research, "nature," emphasizes biological factors in early adolescence such as immaturity of the female reproductive system and inadequate prenatal weight gain. "Nurture," another research focus, stresses sociocultural attributes of teen mothers such as poverty and minority status. Young maternal age alone does not explain the higher rates of low birth weight infants born to adolescent females. Both biological and sociocultural factors, plus lifestyle choices made by adolescents, combine to raise or lower the risk of delivering a low birth weight infant. School health personnel need to link their health promotion efforts to those of other community organizations serving adolescents and their families.     

Risk factors for aboriginal low birthweight, intrauterine growth retardation and preterm birth in the Darwin Health Region

Risk factors for Aboriginal low birthweight (< 2500 g), preterm birth (< 37 weeks' gestation) and intrauterine growth retardation (under the tenth percentile of Australian birthweights for gestational age) were examined in 503 live-born singletons recorded as born to an Aboriginal mother and routinely delivered at the Royal Darwin Hospital between January 1987 and March 1990. Infants born to mothers with body mass index less than 18.5 kg/m2 had five times the risk of having low birthweight and 2.5 times the risk of intrauterine growth retardation. Population-attributable risk percentages suggest that 28 per cent of low birthweight and 15 per cent of growth retardation could be attributed to maternal malnutrition. Risk percentages for maternal smoking of more than half a packet of cigarettes a day were 18 per cent for low birthweight and 10 per cent for growth retardation. For growth retardation, 18 per cent could be attributed to a maternal age under 20 years. Risk factors for preterm birth were predominantly obstetric: the population-attributable risk percentage for pregnancy-induced hypertension was 26 per cent and for other obstetric conditions was 16 per cent. For Aboriginal births in the Darwin Health Region, maternal malnutrition and smoking are key elements in the prevention of low birthweight and intrauterine growth retardation. Teenage pregnancy is an important risk for intrauterine growth retardation, and pregnancy-induced hypertension is a risk for preterm birth.     

Housing and sudden infant death syndrome. The New Zealand Cot Death Study Group

AIMS: This paper examined factors relating to the infants' place of domicile to see whether they increased the risk of sudden infant death syndrome (SIDS) beyond social and environmental effects previously published. METHODS: A case control study was undertaken in New Zealand between the years 1987-90. From all sudden infant death syndrome diagnoses over this time, parents of 393 (81%) sudden infant death syndrome infants consented to participate and these derive the cases. Controls were ascertained by randomly sampling 1800 infants from all babies born over 78% of the country. Parents of 1592 (88%) control infants consented to participate in the study. RESULTS: The relative risk of sudden infant death for infants usually residing in houses rented from the government (State houses) was 1.73 (95% CI: 1.13, 2.66) times that of infants with parents owning their house, after adjusting for likely social, economic and environmental confounding factors. However, the type of housing, construction of housing, heating and age of housing was not associated with sudden infant death syndrome. Although house size, measured in terms of bedroom numbers, was similar for sudden infant death syndrome and control infants (chi 2 = 0.40, df = 2, p = 0.82), the number of people normally residing within these houses was different. Sudden infant death syndrome infants' houses were less likely to have two adults and more likely to have more children normally resident. Density calculations (derived by calculating the children and/or adult numbers divided by bedroom numbers) revealed a non significant increase in relative risk, suggesting that housing overcrowding was not associated with sudden infant death syndrome in New Zealand. CONCLUSIONS: Infants domiciled in State houses are more likely to experience sudden infant death syndrome. However, this increased relative risk for sudden infant death syndrome appears to have little to do with the house per se and, perhaps, more to do with socioeconomic characteristics.     

1988 National Maternal and Infant Health Survey: methods and response characteristics

OBJECTIVES: The 1988 National Maternal and Infant Health Survey (NMIHS) was conducted by the National Center for Health Statistics to study factors related to poor pregnancy outcome, such as adequacy of prenatal care; inadequate and excessive weight gain during pregnancy; maternal smoking, drinking, and drug use; and pregnancy and delivery complications. METHODS: The NMIHS is a nationally representative sample of 11,000 women who had live births, 4,000 who had late fetal deaths, and 6,000 who had infant deaths in 1988. Questionnaires were mailed to mothers based on information from certificates of live birth, reports of fetal death, and certificates of infant death. Information supplied by the mother, prenatal care providers, and hospitals of delivery was linked with the vital records to expand knowledge of maternal and infant health in the United States. RESULTS: The response rates in all three components of the NMIHS differed according to the mothers' characteristics. Mothers were more likely to respond if they were 20-39 years of age, were white, were married, had fewer than four children, entered prenatal care early, had more prenatal visits, had more years of education, or resided in the Midwest Region. The percent of respondents was lower for teenage mothers, mothers of races other than white, and mothers with four or more children, little prenatal care, or fewer years of education. Mothers whose infants weighed less than 2,500 grams were less likely to respond in the live-birth and infant-death components than mothers whose infants weighed 2,500 grams or more. CONCLUSIONS: The NMIHS will provide an invaluable tool for researchers and practitioners seeking solutions to perinatal and obstetric problems.