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Sven Cnattingius

Publications and source records attributed to Sven Cnattingius.

62 records · Page 4Linked to original sources
PubMed2002

Registration artifacts in international comparisons of infant mortality.

Large differences in infant mortality are reported among and within industrialised countries. We hypothesised that these differences are at least partly the result of intercountry differences in registration of infants near the borderline of viability (<750 g birthweight) and/or their classification as stillbirths vs. live births. We used the database of the International Collaborative Effort (ICE) on Perinatal and Infant Mortality to compare infant mortality rates and registration practices in Norway (n = 112484), Sweden (n = 215 908), Israeli Jews (n = 148123), Israeli non-Jews (n = 52 606), US Whites (n = 6 074 222) and US Blacks (n = 1328332). To avoid confounding by strong secular trends in these outcomes, we restricted our analysis to 1987-88, the most recent years for which data are available in the ICE database for all six groups. Compared with Norway (with an infant mortality rate of 8.5 per 1000), the crude relative risks [95% confidence intervals] were 0.75 [0.69,0.81] in Sweden, 0.97 [0.90,1.06] in Israeli Jews, 1.98 [1.81,2.17] in Israeli non-Jews, 0.95 [0.89,1.01] in US Whites and 2.05 [1.95,2.19] in US Blacks. For borderline-viable infants, fetal deaths varied twofold as a proportion of perinatal deaths, with Norway reporting the highest (83.9% for births <500 g and 61.8% for births 500-749 g) and US Blacks the lowest (40.3% and 37.6% respectively) proportions. Reported proportions of live births <500 g varied 50-fold from 0.6 and 0.7 per 10000 in Sweden and Israeli Jews and non-Jews to 9.1 and 33.8 per 10000 in US Whites and Blacks respectively. Reported proportions 500-749 g varied sevenfold from 7.5 per 10000 in Sweden to 16.2 and 55.4 in US Whites and Blacks respectively. After eliminating births <750 g, the relative risks (again with Norway as the reference) of infant mortality changed drastically for US Whites and Blacks: 0.82 [0.76,0.87] and 1.42 [1.33,1.53] respectively. The huge disparities in the ratio of fetal to infant deaths <750 g and in the proportion of live births <750 g among these developed countries probably result from differences in birth and death registration practices. International comparisons and rankings of infant mortality should be interpreted with caution.

Adult↗
PubMed2002

Maternal age, anthropometrics and pregnancy oestriol.

It has been hypothesised that oestrogen exposure in utero influences the risk for breast cancer in adult life. Although several studies report associations between breast cancer and maternal factors associated with birthweight of the offspring - a marker for antenatal oestriol exposure - little is known about the relations between maternal oestrogen levels and these factors per se. We therefore analysed the association between oestriol levels in 188 women in the 17th, 25th, 33rd and 37th weeks of pregnancy, and maternal age, prepregnancy weight, height and pregnancy weight gain. Both maternal prepregnancy body mass index and maternal height were, after controlling for infant birthweight, independently and inversely associated with oestriol levels (P = 0.0021 and P = 0.0006 respectively). We found no association between maternal age or pregnancy weight gain and pregnancy oestriol levels. These findings suggest that the previously reported associations between maternal age and maternal pregnancy weight gain and the offsprings risk of breast cancer are due to factors other than antenatal exposure to oestriol.

Adult↗
PubMed2002

The epidemiology of stillbirth.

Stillbirths account for an increasing proportion of feto-infant mortality. Yet, causes of stillbirth are rarely reported, and the causes of most stillbirths remain unknown. Few studies focus specifically on the epidemiology of stillbirth. Major risk factors include high maternal age, smoking, and overweight. The prevalence of delayed childbearing and, especially overweight, are increasing in most developed countries. The proportion of stillbirth attributable to overweight is likely to increase.

Body Mass Index↗
PubMed2002

Trends in smoking and overweight during pregnancy: prevalence, risks of pregnancy complications, and adverse pregnancy outcomes.

The prevalence of smoking during pregnancy is decreasing in some, but not all, developed countries, as the prevalence of overweight is increasing rapidly in most countries. During pregnancy, smoking increases the risk of placental abruption, but reduces the risk of preeclampsia, while overweight increases the risks of gestational diabetes, preeclampsia, and cesarean delivery. Both smoking and overweight are associated with dose-dependent increases in risks of stillbirth and very preterm birth (< 32 weeks). From a public health perspective, smoking and overweight today probably represent the most important modifiable risk factors for pregnancy complications and adverse pregnancy outcomes.

Adolescent↗
PubMed2002

Pulmonary embolism and stroke in relation to pregnancy: how can high-risk women be identified?

OBJECTIVE: Risks of circulatory diseases are increased substantially during late pregnancy and around the time of delivery. This study was undertaken to determine whether preeclampsia, multiple pregnancy, or cesarean delivery account for the majority of pregnancy-related risks of pulmonary embolism and stroke (caused by hemorrhage, infarction, and intracranial venous thrombosis). STUDY DESIGN: We analyzed a population-based cohort of 1,003,489 deliveries in Sweden. Relative risks of pulmonary embolism and stroke were modeled by use of Poisson regression. RESULTS: Preeclampsia was associated with 3- to 12-fold increases in risks of pulmonary embolism and stroke during late pregnancy, at delivery, and in the puerperium, and similar increases in risks were also observed for multiple pregnancies and cesarean delivery. These strong associations could not explain the overall pregnancy-related risks of pulmonary embolism and stroke. CONCLUSION: Preeclampsia, multiple birth, and cesarean delivery are important risk factors for pulmonary embolism and stroke, but they do not account for the majority of the excess risks associated with pregnancy.

Adult↗
PubMed2002

Childhood leukemia and magnetic fields in infant incubators.

In studies of magnetic field exposure and childhood leukemia, power lines and other electrical installations close to the children's homes constitute the most extensively studied source of exposure. We conducted a study to assess whether exposure to magnetic fields in infant incubators is associated with an increased leukemia risk. We identified all children with leukemia born in Sweden between 1973 and 1989 from the national Cancer Registry and selected at random one control per case, individually matched by sex and time of birth, from the study base. We retrieved information about treatment in infant incubators from medical records. We made measurements of the magnetic fields inside the incubators for each incubator model kept by the hospitals. Exposure assessment was based on measurements of the magnetic field level inside the incubator, as well as on the length of treatment. For acute lymphoblastic leukemia, the risk estimates were close to unity for all exposure definitions. For acute myeloid leukemia, we found a slightly elevated risk, but with wide confidence intervals and with no indication of dose response. Overall, our results give little evidence that exposure to magnetic fields inside infant incubators is associated with an increased risk of childhood leukemia.

Adolescent↗
PubMed2002

Perinatal risk factors for infantile autism.

BACKGROUND: Etiologic hypotheses in infantile autism suggest a strong genetic component, as well as possible environmental risks linked to early fetal development. We evaluated the association of maternal, pregnancy, delivery, and infant characteristics and risk of infantile autism. METHODS: We conducted a case-control study nested within a population-based cohort (all Swedish children born in 1974-1993). We used prospectively recorded data from the Swedish Birth Register, which were individually linked to the Swedish Inpatient Register. Cases were 408 children (321 boys and 87 girls) discharged with a main diagnosis of infantile autism from any hospital in Sweden before 10 years of age in the period 1987-1994, plus 2,040 matched controls. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The risk of autism was associated with daily smoking in early pregnancy (OR = 1.4; CI = 1.1-1.8), maternal birth outside Europe and North America (OR = 3.0; CI = 1.7-5.2), cesarean delivery (OR = 1.6; CI = 1.1-2.3), being small for gestational age (SGA; OR = 2.1; CI = 1.1-3.9), a 5-minute Apgar score below 7 (OR = 3.2, CI = 1.2-8.2), and congenital malformations (OR = 1.8, CI = 1.1-3.1). No association was found between autism and head circumference, maternal diabetes, being a twin, or season of birth. CONCLUSIONS: Our findings suggest that intrauterine and neonatal factors related to deviant intrauterine growth or fetal distress are important in the pathogenesis of autism.

Asphyxia Neonatorum↗