Maternal pre-eclampsia/eclampsia and the risk of sudden infant death syndrome in offspring

To determine whether maternal exposure to pre-eclampsia/eclampsia during pregnancy increases the risk of sudden infant death syndrome (SIDS) in offspring, we conducted a population-based case-control study using the California linked birth and death certificate data. All infants who died of SIDS (ICD-9 code 798.0) during 1989-91 were identified as cases. More than 96% of the identified SIDS cases were diagnosed through autopsy. Ten controls who did not die from SIDS were randomly selected for each case from the birth certificate matched to the case on the year of birth. Among 2,029 cases and 21,037 controls included in the final analysis, mothers of 49 cases (2.4%) and 406 controls (1.9%) had a diagnosis of either pre-eclampsia or eclampsia noted on the birth certificate. After adjustment for maternal age, prenatal smoking, race/ethnicity, parity, maternal education, gestational age at the initial visit for prenatal care, infant year of birth and infant sex, maternal pre-eclampsia/ eclampsia during pregnancy was associated with a 50% increased risk of SIDS in the offspring (odds ratio = 1.5, 95% confidence interval 1.1, 2.0). Potential under-reporting of pre-eclampsia/eclampsia on the birth certificates was likely to be non-differential and is unlikely to explain the finding. Fetal hypoxia resulting from pre-eclampsia/ eclampsia or immunological aetiology affecting the risk of both pre-eclampsia/eclampsia and SIDS may explain the finding.     

Prenatal and intrapartum events and sudden infant death syndrome

The purpose of this study was to evaluate specific pregnancy and labour and delivery events that may increase the risk of sudden infant death syndrome (SIDS). A matched case-control study was conducted in five counties in southern California, using California death certificate records. The sample consisted of 239 Caucasian, African-American, Hispanic and Asian mothers of SIDS infants and 239 mothers of control infants matched on sex, race, birth hospital and date of birth. Mothers participated in a detailed telephone interview and provided access to obstetric and paediatric records. More case than control mothers reported a family history of anaemia (OR=2.12, P < 0.001). Placental abruptions were strongly associated with SIDS (unadjusted OR=7.94, [95% CI 1.34,47.12]). There was an increased risk of SIDS death associated with maternal anaemia during pregnancy (OR=2.51, [95% CI 1.25,5.03]), while simultaneously adjusting for maternal smoking during pregnancy, maternal years of education and age, parity, infant birthweight, gestational age, medical conditions at birth, infant sleep position and post-natal smoking. Interactions of anaemia and prenatal smoking as well as anaemia and post-natal smoking were not statistically significant. There were no other statistically significant differences between case and control mothers for pregnancy conditions, labour and delivery events (e.g. caesarean sections, anaesthesia, forceps) or newborn complications (e.g. nuchal cord, meconium aspiration). Anaemia and placental abruptions were significantly associated with an increased risk of SIDS; both are circumstances in which a fetus may become hypoxic, thereby compromising the subsequent growth, development and ultimate survival of the infant.     

Ethnic differences in the incidence of the sudden infant death syndrome (SIDS) in Victoria, Australia 1985–1989

Summary. In order to describe ethnic differences in the incidence of the sudden infant death syndrome (SIDS) records of all livebirths in the State of Victoria, Australia, 1985–1989, excluding those who died in the first month of life, were linked to death certificates. Cases were defined as infants dying with a diagnosis of SIDS between 1 month and 1 year of age ( n = 601) from the cohort of 308052 neonatal survivors. Ethnicity was defined by the mother's country of birth. The SIDS incidence was 2.04/1000 in infants of Australian-born mothers. The relative risk of SIDS was 0.28 (95% confidence interval (CI) 0.15,0.55) in infants whose mothers had been born in Southern Europe and 0.48 (95% CI 0.29, 0.78) in infants whose mothers had been born in Asia. SIDS in infants of Australian-born mothers was associated with low maternal age, high parity, marital status other than married, male sex, multiple birth, low birthweight and preterm birth. After adjustment for those factors in a case-control analysis using a logistic regression model the adjusted odds ratio for SIDS was 0.34 (95% CI 0.17, 0.69) comparing infants whose mothers were born in Southern Europe with infants of Australian-born mothers, and 0.60 (95% CI 0.35, 1.04) for infants whose mothers were born in Asia, compared with infants of the Australian-born. Thus there are substantial ethnic differences in SIDS which are not explained by the classic social and perinatal risk factors.     

The epidemiology of sudden infant death in upstate New York: II: birth characteristics.

This study describes the epidemiology of sudden infant death syndrome (SIDS) among infants born during 1974 to upstate New York residents. Birth certificate characteristics for 184 SIDS cases are compared with those of 417 infants dying from other causes in the same age range, 7-365 days. The results confirm the following as infant risk factors: fall or winter birth, low birthweight for gestational age, twin birth, and live birth order three or more. Maternal risk factors include: age under 20, abnormal uterine bleeding during pregnancy, late initiation of prenatal care, less than 12 years of education and single marital status. The increased risk for mothers who first gave birth in their teens and for second-born twins has not been previously reported. The evidence that SIDS babies are small for gestational age, that twins, especially the second born, and babies whose mothers experienced abnormal uterine bleeding during pregnancy are all at increased risk of SIDS suggests that perinatal stress leading to hypoxia is one of the components that determine the risk of SIDS.     

Maternal placental abnormality and the risk of sudden infant death syndrome

To determine whether placental abnormality (placental abruption or placental previa) during pregnancy predisposes an infant to a high risk of sudden infant death syndrome (SIDS), the authors conducted a population-based case-control study using 1989-1991 California linked birth and death certificate data. They identified 2,107 SIDS cases, 96% of whom were diagnosed through autopsy. Ten controls were randomly selected for each case from the same linked birth-death certificate data, matched to the case on year of birth. About 1.4% of mothers of cases and 0.7% of mothers of controls had either placental abruption or placenta previa during the index pregnancy. After adjustment for potential confounders, placental abnormality during pregnancy was associated with a twofold increase in the risk of SIDS in offspring (odds ratio = 2.1, 95% confidence interval 1.3-3.1). The individual effects of placental abruption and placenta previa on the risk of SIDS did not differ significantly. An impaired fetal development due to placental abnormality may predispose an infant to a high risk of SIDS.     

Tobacco smoke exposure at one month of age and subsequent risk of SIDS--a prospective study

The aim of this investigation was to identify the sources of postnatal exposure to tobacco smoke at 1 month of age and to examine their relation to sudden infant death syndrome (SIDS). The Tasmanian Infant Health Survey was a prospective cohort study undertaken from 1988 to 1995. It involved 9,826 infants (89% of eligible infants) at higher risk of SIDS. Subsequently 53 eligible infants died of SIDS. Hospital interviews were available on 51 and home interviews on 35 SIDS infants. Urinary cotinine assays were conducted using gas-liquid chromatography (n = 100). Within a predictive model that explained 63% of urinary cotinine variance, the strongest predictor of cotinine and also of SIDS was maternal smoking, though the effects of prenatal and postnatal smoking could not be separated. However, for particular smoking-related behaviors, there was a discordance between prediction of cotinine concentration and prediction of risk of SIDS. If smoking mothers did not smoke in the room with the baby, the cotinine level in the infant's urine was reduced by a little more than a half (p = 0.009), but this was not associated with a reduction in SIDS risk (odds ratio = 1.09, 95% confidence interval 0.47-2.55). Similarly, the presence of other adult resident smokers was associated with a 63% increase in urinary cotinine (p = 0.047) but not with increased SIDS risk (odds ratio = 0.69, 95% confidence interval 0.34-1.40). However, the study lacked the power to detect modest effects, that is, those altering risk less than twofold.     

Sudden infant death syndrome: seasonality and a biphasic model of pathogenesis.

STUDY OBJECTIVE--This paper examines the relationship between season, age, and the sudden infant death syndrome (SIDS). It provides a theoretical model for the pathogenesis of SIDS and uses it as a framework to consider risk factor mechanism. DESIGN--A case series analysis was used to examine season and age in relation to SIDS and seasonal pattern and age at death distribution of perinatal risk factors. SETTING--The source population for the SIDS cases in this study was all live births in the state of Tasmania, Australia, 1975 to 1987 inclusive. SUBJECTS--Cases were all infants born 1975 to 1987 who died of SIDS on whom birth notification information was available (n = 348). The live birth cohort 1980-87 (n = 55,944) was used as the control population for risk factor identification. MEASUREMENTS AND MAIN RESULTS--The median ages of death for spring, summer, autumn, and winter born infants were 115, 103.5, 91 and 78 days. Spring and summer born infants died at a significantly older median age than winter born infants. The month of birth distribution of SIDS cases did not alter significantly from a uniform, nonseasonal distribution (p greater than 0.25) but month of death was seasonally distributed (p less than 0.01). Premature and low birthweight infants died at an older median age (p less than 0.05) than term and non-low-birthweight infants. An excess of male infant deaths and infant deaths to older mothers occurred during winter (p less than 0.05). CONCLUSIONS--The pathogenesis of SIDS can be represented as a biphasic model with three pathways of risk factor operation. In this study, season influenced the age at death of SIDS infants. We propose that risk factors with a strong seasonal distribution are likely to be operating in the postnatal period.     

Risk factors for sudden infant death syndrome in the US Collaborative Perinatal Project

Risk factors for sudden infant death syndrome (SIDS) were studied among infants born to the nearly 56,000 women enrolled in the US Collaborative Perinatal Project from 1959 through 1966. The 193 SIDS cases identified in the cohort were compared with 1930 controls randomly selected from infants who survived the first year of life. The previously documented excess risk associated with black race disappeared after adjusting for maternal education and family income. Maternal smoking, maternal anaemia during pregnancy, and lack of early prenatal care were all positively associated with SIDS. After adjustment for gestational age, infants with low weight and length at birth were still at increased SIDS risk, suggesting that intrauterine growth retardation may be a risk factor. Neurological abnormalities diagnosed before death were associated with SIDS, but much of the association was removed by adjusting for birthweight. The negative association of breastfeeding with SIDS was much reduced upon adjustment by maternal education and birthweight. These findings may have important implications in our understanding of the epidemiology of SIDS.     

Pacifier Use and Sids: Evidence for a Consistently Reduced Risk

Pacifier use at sleep time decreases sudden infant death syndrome (SIDS) risk. It is yet unclear whether pacifier use can modify the impact of other sleep-related factors upon SIDS risk. The objective of this study was to examine the association between pacifier use during sleep and SIDS in relation to other risk factors and to determine if pacifier use modifies the impact of these risk factors. Data source was a population based case–control study of 260 SIDS deaths and 260 matched living controls. Pacifier use during last sleep decreased SIDS risk (aOR 0.30, 95% CI 0.17–0.52). Furthermore, pacifier use decreased SIDS risk more when mothers were ≥20 years of age, married, nonsmokers, had adequate prenatal care, and if the infant was ever breastfed. Pacifier use also decreased the risk of SIDS more when the infant was sleeping in the prone/side position, bedsharing, and when soft bedding was present. The association between adverse environmental factors and SIDS risk was modified favorably by pacifier use, but the interactions between pacifier use and these factors were not significant. Pacifier use may provide an additional strategy to reduce the risk of SIDS for infants at high risk or in adverse sleep environments.     

Low Birth Weight Across Generations

Objectives: This study sought to determine the relationship between maternal birth weight, prenatal care usage, and infant birth weight. Methods: Stratified and logistic regression analyses were performed on a dataset of computerized Illinois vital records of White (N = 187,074) and African-American (N = 58,856) infants born between 1989 and 1991 and their mothers born between 1956 and 1975. Results: Among White mothers who received adequate prenatal care, the low birth weight (<2500 g) rate was 4% for infants of former low birth weight mothers (N = 5230) compared to 2.1% for infants of former nonlow birth weight mothers (N = 93,011), relative risk equaled 1.9(1.7–2.2); the population attributable risk of maternal low birth weight was 4.1%. Among African American mothers who received adequate prenatal care, the low birth weight rate was 15% for infants of former low birth weight mothers (N = 2196) compared to 7.2% for infants of former nonlow birth weight mothers (N = 14,607), relative risk equaled 2.1(1.9–2.4); the population attributable risk of maternal low birth weight was 10.9%. The maternal–infant birth weight associations were consistent across all maternal age, education, marital status, and prenatal care categories. Conclusions: Maternal low birth weight is a risk factor for infant low birth weight independent of risk status during the current pregnancy. A greater percentage of low birth weight African American (compared to White) infants are attributable to maternal low birth weight.     

Preterm delivery and age of SIDS death

PURPOSE: The aim of the study is to (i) reexamine risk factors for sudden infant death syndrome (SIDS) and (ii) describe the relationship between length of gestation and age at death from SIDS. METHODS: To evaluate risk factors for SIDS, we used multivariable logistic regression and included maternal demographic characteristics, maternal health and behavioral factors, and infant characteristics, including fetal growth, using US national linked birth and death files from 1996 to 1998. We used multivariable linear regression with mean postnatal age of death as the outcome of interest, controlling for the factors listed (referent length of gestation, 40 to 41 weeks). RESULTS: The crude SIDS rate was 0.7 deaths/1000 live births (8199 deaths). Length of gestation was a strong risk factor for SIDS, with the adjusted odds ratio (OR) greatest at shorter gestations: 28 to 32 weeks (OR, 2.9; 95% confidence interval, 2.6-3.2). Infants with gestations of 22 to 27 and 28 to 32 weeks died at mean ages of 20.9 (SD = 0.8) and 15.3 (SD = 0.5) weeks, respectively (p < or = 0.002). Term infants (40 to 41 weeks) died of SIDS at an adjusted mean age of 14.5 (SD = 0.4) weeks. CONCLUSIONS: Preterm birth continues to be a strong risk factor for SIDS after controlling for fetal growth. With increasing gestational age, mean age of SIDS death decreases considerably, with the postnatal age of death of very preterm infants 6 weeks later than that of term infants.     

Racial disparity in pregnancy-related mortality following a live birth outcome

PURPOSE: African-American women have a 2- to 4-fold increased risk of pregnancy-related death compared with Caucasian women. We conducted this study to determine if differences in a combination of socioeconomic and medical risk factors may explain this racial disparity in pregnancy-related death. METHODS: Pregnancy-related deaths of African-American (N=60) and Caucasian (N=47) women were identified from review of pregnancy-associated deaths (N=400) ascertained through cause of death on death certificates, electronic linkage of birth and death files, and review of the hospital discharge database for the State of North Carolina, during the period between 1992 and 1998. Controls (N=3404) were randomly selected from all live births for the same 7-year period. Logistic regression was used to model the association between race and pregnancy-related death. RESULTS: The unadjusted odds ratio (OR) for pregnancy-related death for African-Americans compared with Caucasians was 3.07 (95% confidence interval [CI], 2.08, 4.54). After controlling for gestational age at delivery, maternal age, income, hypertension, and receipt of prenatal care, African-American race remained a significant predictor variable (OR 2.65 [95% CI 1.73, 4.07]). CONCLUSIONS: Our analysis confirms that there is a strong association between race and pregnancy-related death, even after adjusting for potential predictors and confounders.     

Similarities and disparities in maternal risk and birth outcomes of white and Japanese-American mothers

Summary. This study compares the maternal sociodemographic and prenatal care characteristics and birth outcomes of US resident white and Japanese-American mothers, using data from the state of Hawaii. The specific focus is to determine to what extent these factors can explain variations in newborn maturity and mortality indicators. Single livebirths to resident, non-military dependent white and Japanese-American mothers were selected for analysis from the 1979–1990 linked livebirth-infant death files from Hawaii. Compared with white mothers, Japanese-American mothers were significantly more likely to be married, age 18 years and older, have higher educational attainment, and have adequate prenatal care utilisation. The majority of Japanese-American mothers were born in Hawaii, while the majority of white mothers were born on the US mainland. The mean birthweight of Japanese-American infants was 200 g lighter than that of white infants. Infant mortality rates (IMRs) for both groups were below the US Year 2000 Health Objective. After controlling for maternal sociodemographic and prenatal care factors with logistic regression, Japanese-American infants had significantly higher risks of low birthweight, preterm and very preterm birth and of being small-for-gestational age. These findings indicate that populations with preferential maternal sociodemographic and prenatal care risk indicators may still exhibit higher low birthweight percentages, but achieve comparatively low IMRs.     

Perinatal characteristics of newborns relinquished at birth

Demographic, perinatal, and newborn characteristics of single mothers relinquishing their newborns for adoption (N = 111) were compared with randomly selected and matched groups of mothers keeping their infants. Relinquishing mothers were younger, more apt to be Caucasian, Catholic, primiparous, and economically independent of government assistance, less likely to plan their pregnancies, and later starting prenatal care. In general, their pregnancies and infants were at no higher neonatal risk than those of other single mothers.     

Sudden infant death syndrome in Australian Aboriginal and non-Aboriginal infants: an analytical comparison

Summary. Our previous research has shown that the sudden infant death syndrome (SIDS) rate for Aboriginal infants in Western Australia (WA) is markedly higher than that for non-Aboriginal infants. The aim of this study was to identify factors that may be important in explaining this disparity. A case-control study was conducted based on routinely collected data for the population of WA singleton births from 1980 to 1990 inclusive. Cases were infants bom and classified as dying from SIDS in WA (Aboriginal n = 88; non-Aboriginal n = 409). Controls were infants born in WA and not classified as dying from SIDS; 2% samples of both Aboriginal and non-Aboriginal infants were included. The risk of dying from SIDS in Aboriginal infants was 3.86 times [95% confidence interval (CI) = 2.98 to 5.02] that in non-Aboriginal infants. Statistically significant univariable risk factors for SIDS in Aboriginal infants were preterm birth, low birthweight and small-for-gestarional-age; for non-Aboriginal infants they included these factors as well as single marital status, young maternal age, parity of one or greater and male sex. Comparing Aboriginal with non-Aboriginal controls, most of the risk factors were more common in the Aboriginal population. Multiple logistic regression analysis indicated that Aboriginal infants were 1.43 times [95% CI = 1.04 to 1.95] more likely to die from SIDS than non-Aboriginal infants. Differences in the risk factor profile for Aboriginal and non-Aboriginal infants were sought using interaction terms. The only important differences were that the risk of SIDS in Aboriginal infants, unlike that in non-Aboriginal infants, appeared not to be strongly related to male sex or to single marital status. Thus, the results show that the disparity between the incidence of SIDS in the Aboriginal and non-Aboriginal populations can be explained largely, although not totally, by the high prevalence of routinely recorded risk factors in the Aboriginal population. A limitation of this study is that data on the postnatal nsk factors of prone sleeping, maternal smoking and non-breastfeeding were unavailable. The residual excess risk for Aboriginal infants may be a result of these recognised postnatal risk factors and /or other infant care practices that are not routinely recorded in our data base, or to underlying social and economic conditions. Further study of all these potential risk factors is warranted.     

Infant sleeping position and the risk of sudden infant death syndrome in California, 1997-2000

To assess the association between infant sleeping position and risk of sudden infant death syndrome (SIDS) in an ethnically diverse US population, the authors conducted a population-based case-control study in 11 counties in California from May 1997 through April 2000. The authors conducted in-person interviews with the mothers of 185 SIDS cases and 312 randomly selected race/ethnicity- and age-matched controls to collect information on sleeping positions. Infants who had last been put down to sleep in the prone or side position were at greater risk of SIDS than were infants who had last been put down on their backs (adjusted odds ratio (AOR) = 2.6 (95% confidence interval (CI): 1.5, 4.5) and AOR = 2.0 (95% CI: 1.2, 3.4) for the prone and side positions, respectively). The risk of SIDS was especially high for an unstable side position in which an infant was placed on its side and found prone (AOR = 8.7, 95% CI: 3.3, 22.7). Infants who were usually placed on their backs to sleep but had last been put down in the prone or side position (an unaccustomed position) had a significantly high risk of SIDS (AOR = 8.2 (95% CI: 2.6, 26.0) and AOR = 6.9 (95% CI: 2.3, 20.6) for the prone and side positions, respectively). Infants placed in an unaccustomed prone or side sleeping position had a higher risk of SIDS than infants who were always placed prone or on the side.     

西藏藏族孕产妇产前检查次数与低出生体重儿的关联

  目的  了解西藏藏族孕产妇产前检查次数与低出生体重儿的关联,为提高产前保健质量、减少低出生体重儿的发生提供参考。  方法  选取2012年1月-2018年12月在西藏拉萨市某医院分娩的藏族产妇及新生儿为研究对象,收集所有单胎活产分娩孕产妇的基础资料、分娩资料及新生儿出生资料。采用Logistic回归模型对孕产妇产前检查次数与其分娩的新生儿出生体重进行关联性分析。  结果  5 563例孕产妇,规范产前检查率为10.48%。孕产妇所分娩新生儿中,低出生体重儿占11.32%。随着孕产妇产检次数的增加,新生儿低出生体重率呈现下降趋势（χ2=14.57,P=0.002）。多因素Logistic回归模型显示,在控制了孕产妇年龄、胎儿性别、分娩方式、胎儿窒息等因素后,未接受产前检查和接受1~2次产前检查的孕产妇分娩的低出生体重儿发生率分别是接受规范产前检查孕产妇的1.41倍（95% CI:1.00~1.98）和2.34倍（95% CI:1.09~5.02）。  结论  西藏藏族孕产妇接受规范的产前检查的比例较低,存在较高的低出生体重儿的发生风险。建议加强少数民族地区的妇幼保健工作质量,保障母婴安全。     

Within prisons,is there an association between the quantity of prenatal care and infant birthweight?

There is still controversy surrounding the effectiveness of prenatal care in reducing low birthweight. In addition, very few studies have assessed the relationship between prenatal care and infant birthweight among pregnant women within the prison system. We sought to ascertain whether there is an association between the quantity of prenatal care and infant birthweight among pregnant women within such a setting. We examined the prison medical records of 147 infants born to women delivering at term (37-41 weeks of gestation) between 1 January 2002 and 31 December 2004 who were incarcerated during pregnancy in Texas state prisons. Linear regression was used to evaluate the association between the number of prison prenatal care visits and infant birthweight while adjusting for potential confounders (age, gravidity, maternal education, maternal race, history of substance use, history of alcohol use, history of tobacco use and the presence of any chronic disease). We also adjusted for the interaction between the gestational age at admission to prison and the number of prison prenatal care visits. There was a statistically significant 120.5 g increase in adjusted mean birthweight with each additional prison prenatal care visit (P = 0.001) among study infants whose mothers entered prison during the first trimester. This trend was not observed among women who came in after the first trimester. There appears to be a positive association between the amount of prison prenatal care and infant birthweight among incarcerated pregnant women delivering at term, but this association appears to be limited to women entering prison during the first trimester of pregnancy.