Biomedical subjects

Sven Cnattingius

Publications and source records attributed to Sven Cnattingius.

At least 37 records · Page 2Linked to original sources

PubMed2005

Chromosomal anomalies in first-trimester miscarriages.

BACKGROUND: It is well known that a large proportion of first-trimester spontaneous abortions is caused by chromosomal disorders. The present study represents a unique material and the success rate of the karyotyping was high. METHODS: Chromosomal analysis from chorionic villus sampling of 259 of 304 consecutive first-trimester miscarriages in the Uppsala County, Sweden is presented. RESULTS AND CONCLUSIONS: An abnormal karyotype was found in 61% of the cases. Autosomal trisomies were most frequently detected (in 37% of the karyotyped samples), followed by polyploidies (9%) and monosomy X (6%). Cases with an extra sex chromosome constituted approximately 5% of the karyotyped abortions, with a remarkable high frequency of 47,XXY (3.4%), that is approximately 40 times greater the prevalence of Klinefelter syndrome among live birth. Similar to autosomal chromosome abnormalities, present finding indicates that the majority of sex chromosome abnormalities do not survive to term. Autosomal trisomies and an extra X-chromosome in males (47,XXY) were associated with an advanced maternal age, whereas monosomy X as well as polyploidy changes seems to be inversely related to the age of the mother. The single most common aberration was trisomy 16, which was found in 14% of the chromosomally abnormal abortions.

Abortion, Spontaneous↗

PubMed2005

Lactate determination in vaginal fluids: a new method in the diagnosis of prelabour rupture of membranes.

OBJECTIVES: To assess whether lactate determination in vaginal fluids, 'Lac test', can be used as a diagnostic test for prelabour rupture of membranes (PROM) and to derive the best cutoff value for a positive test. DESIGN: Prospective observational study. SETTING: Labour ward at Söder Hospital in Stockholm, a large clinical service. POPULATION: Women living in the centre of Stockholm, the capital of Sweden. METHODS: We selected 200 cases with a history of suspect PROM for determination of lactate concentrations in vaginal fluid. In 100 of these cases, actim PROM tests were also analysed. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive and negative predictive values, likelihood ratios (LR) and Kappa indices in the identification of visible amniotic fluid at speculum examination. RESULTS: A lactate concentration > or =4.5 mmol/L was found to be the best cutoff value for a positive test. The 'Lac test' had a sensitivity of 86%, specificity 92%, positive and negative predictive values of 92% and 87%, respectively. Corresponding values for the actim PROM test were 60%, 98%, 97% and 71%. LR for a positive 'Lac test' was 10.75 and for a negative test 0.15. Corresponding values for the PROM test were 30.0 and 0.4, respectively. The Kappa index was higher for the 'Lac test' as compared with the actim PROM test (78% and 59%, respectively). CONCLUSION: Lactate determination is a valid test in cases with a history of suspect PROM and may even be a better predictor than the actim PROM test.

Adult↗

PubMed2005

Birth centre care over a 10-year period: infant morbidity during the first month after birth.

AIM: To study morbidity during the first month of life affecting infants of mothers booked for birth centre care during pregnancy. METHODS: 3238 live single-born infants whose mothers were admitted to an in-hospital birth centre, located at South Hospital in Stockholm, between 1989 and 2000 were compared with 179,502 infants whose mothers received standard maternity care in the Stockholm region during the same period, and who fulfilled the same medical inclusion criteria as those of the birth centre group. Information on other exposures and outcomes was collected from the Swedish Medical Birth and Hospital Discharge Registers. Logistic regression analyses were performed to calculate the odds ratio (OR), using 95% confidence intervals (95% CI). RESULTS: Compared with infants born in standard care, infants in the birth centre group had a higher risk of respiratory problems (OR 1.39; 95% CI 1.14-1.69), a difference correlated to less serious respiratory diagnoses. However, the difference was not statistically significant if the birth centre group was compared only with infants born in standard care at South Hospital (OR 1.18; 95% CI 0.94-1.47). Birth centre care was associated with a lower risk of fractures (OR 0.40; 95% CI 0.25-0.63). CONCLUSION: Birth centre care was not associated with severe infant morbidity and even appeared to reduce the risk of birth trauma, such as clavicle and other fractures.

Birthing Centers↗

PubMed2005

Fetal growth restriction and schizophrenia: a Swedish twin study.

Obstetric complications increase the risk of schizophrenia. However, it is not known whether there is a causal relation or whether the association is mediated by genetic and/or shared environmental effects. The aim of this study was to investigate the associations between birthweight, other birth characteristics, and schizophrenia. Twin pairs discordant for schizophrenia will also control for unmeasured genetic and shared environmental effects. Prospectively filed obstetric records were used for a cohort analysis of 11,360 same-sexed twins, and within-twin pair analyses were conducted on 90 twin pairs discordant for schizophrenia. The results from the cohort study showed that low birthweight (less than or equal to 1999 grams; odds ratio [OR] 1.67, 95% confidence interval [CI] 0.88-3.14 and 2000-2299 grams; OR 1.79, 95% CI 1.07-3.01) and small head circumference (less than or equal to 31.5 cm; OR 1.61, 95% CI 1.03-2.51) were associated with later development of schizophrenia. The associations remained in the within-pair analyses. The association between low birthweight and schizophrenia is partly a function of reduced fetal growth. Fetal growth restriction seems to be associated with risk of schizophrenia independently of familial factors.

Birth Weight↗

PubMed2004

Maternal and fetal genetic factors account for most of familial aggregation of preeclampsia: a population-based Swedish cohort study.

There is accumulated evidence for genetic influences on preeclampsia. However, no study has been able to separate the effects of maternal and fetal genetic factors from environmental factors, and there are still uncertainties about the origin and magnitude of the genetic effects. We used the population-based Swedish Birth and Multi-Generation Registries to identify a cohort of women who gave birth from 1987 through 1997. In order to separate the genetic and environmental contributions to preeclampsia, we analyzed pregnancy outcomes from families joined by full siblings. We included information from 244,564 sibling pairs (62,236 sister pairs, 63,288 brother pairs, and 119,040 sister-brother pairs), who had 701,488 pregnancies. We found that 35% of the variance in liability of preeclampsia was attributable to maternal genetic effects, 20% to fetal genetic effects (with similar contribution of maternal and paternal genetic effects), 13% to the couple effect, less than 1% to shared sibling environment, and 32% to unmeasured factors. Among women and men without a history of preeclampsia, partner change reduced the risk of preeclampsia (odds ratio, 0.6; 95 percent confidence interval, 0.4-0.9). Genetic factors account for more than half of the liability of preeclampsia, and maternal genes contribute more than fetal genes. We suggest that the couple effect is due to a genetic interaction between mother and father.

Adult↗

PubMed2004

Previous preterm and small-for-gestational-age births and the subsequent risk of stillbirth.

BACKGROUND: Some causes of stillbirth may also lead to fetuses that are small for gestational age (have a low birth weight with respect to their gestational age) or are delivered preterm (before 37 weeks of gestation). It is not known whether the birth of a previous small-for-gestational-age or preterm infant increases the subsequent risk of stillbirth. METHODS: We assessed the associations between previous adverse outcomes of pregnancy and the risk of stillbirth in a nationwide Swedish study of 410,021 women who delivered first and second consecutive singleton infants between 1983 and 1997. There were 1842 and 1062 stillbirths during the first and second pregnancies, respectively. RESULTS: As compared with women whose first infant was born at term (37 weeks of gestation or more) and was not small for gestational age, women whose first infant was born at term or preterm and was small for gestational age had an increased risk of stillbirth during their second pregnancy. The odds ratios for subsequent stillbirth, after adjustment for covariates known to be associated with an increased risk of stillbirth, were 2.1 (95 percent confidence interval, 1.6 to 2.8) among women with a first infant who was born at term and was small for gestational age, 3.4 (95 percent confidence interval, 2.1 to 5.6) among women with a first infant who was moderately (32 to 36 weeks of gestation) preterm and small for gestational age, and 5.0 (95 percent confidence interval, 2.5 to 9.8) among women with a first infant who was very (before 32 weeks of gestation) preterm and was small for gestational age. The odds ratio for subsequent stillbirth among women with a first stillborn infant was 2.5 (95 percent confidence interval, 1.4 to 4.7), as compared with women whose first infant was not stillborn. The rates of stillbirth in second pregnancies ranged from 2.4 per 1000 births among women whose first infant was born at term and was not small for gestational age to 19.0 per 1000 births among women whose first child was very preterm and was small for gestational age. CONCLUSIONS: Delivery of a previous small-for-gestational-age infant is an important predictor of the subsequent risk of stillbirth, particularly if the infant was delivered preterm.

Adult↗

PubMed2004

Maternal smoking during pregnancy and risk of brain tumors in the offspring. A prospective study of 1.4 million Swedish births.

OBJECTIVE: Studies of the effect of maternal smoking during pregnancy on development of brain tumors in the offspring generally have found no increase in risk but most have mainly relied on retrospective exposure assessment. We conducted a prospective study on a large birth cohort in Sweden. METHODS: Women giving birth during 1983-1997 were classified as smokers or non-smokers based on information ascertained at the first prenatal visit and recorded in the Swedish Birth Register. Follow-up of brain tumor incidence among offspring through 1997 was achieved by linkage with the Swedish Cancer Register. Hazard ratios were estimated using Cox proportional hazard regression, adjusting for demographic characteristics available in the Birth Register. RESULTS: Brain tumors (n=480) occurred at a rate of 4.5 cases per 100,000 person-years. Children of women who smoked during pregnancy had an increased incidence of brain tumors (hazard ratio = 1.24; 95% confidence interval: 1.01-1.53). The increase in risk was similar for benign and malignant tumors, and was most apparent for astrocytoma. The effect of smoking on the occurrence of brain tumors was seen most strongly among 2-4 year-old children. CONCLUSIONS: These results support a role for maternal smoking during pregnancy in the etiology of childhood brain tumors. Our findings should be confirmed in other prospective studies.

Adolescent↗

PubMed2004

Previous pregnancy loss: risks related to severity of preterm delivery.

OBJECTIVES: The purpose of this study was to examine the association between previous pregnancy losses and subsequent risk of preterm delivery. STUDY DESIGN: A population-based Swedish study including information on all births and women's hospital admissions for pregnancy loss (n = 601,883) in Sweden between 1987 and 2000 was performed. The risk of preterm delivery after a previous pregnancy loss was estimated using logistic regression models. The risk of preterm premature ruptures of the membranes (PROM), preterm labor, and other reasons for preterm delivery was also assessed. RESULTS: Previous spontaneous abortions and missed abortions were associated with increased risks of preterm delivery, and the risks increased with severity of preterm delivery. Previous pregnancy loss increased the risk of preterm PROM and preterm labor foremost in deliveries before 32 weeks, but was not associated with other reasons of very preterm delivery. CONCLUSION: Our results support the hypothesis that pregnancy loss and early preterm delivery may share etiologic causes.

Abortion, Spontaneous↗

PubMed2004

Intellectual performance in young adult males born small for gestational age.

UNLABELLED: Children born small for gestational age (SGA) have increased risk of neurological dysfunction. The aim of this study was to analyze intellectual performance in early adult age in children born SGA, and especially the effect of catch up growth in height. METHODS: Data on gestational age and birth size were taken from the Swedish Birth Register and data on adult height and intellectual performance from the Swedish Conscript Register. RESULTS: Low birth weight, birth length and head circumference increased the risk of subnormal intellectual and psychological performance in males born SGA. Very low gestational age also increased the risk. However, the most important predictor was the absence of catch up growth to a height above -2 SDS in individuals born SGA.

Adolescent↗

PubMed2004

The epidemiology of smoking during pregnancy: smoking prevalence, maternal characteristics, and pregnancy outcomes.

The prevalence of smoking during pregnancy varies markedly across countries. In many industrialized countries, prevalence rates appear to have peaked and begun to decline, whereas in other countries smoking is becoming increasingly common among young women. Randomized controlled trials have shown that smoking interventions during pregnancy have had limited success. Smoking during pregnancy is in many countries recognized as the most important preventable risk factor for an unsuccessful pregnancy outcome. Smoking is causally associated with fetal growth restriction, and increasing evidence also suggests that smoking may cause stillbirth, preterm birth, placental abruption, and possibly also sudden infant death syndrome. Smoking during pregnancy also is generally associated with increased risks of spontaneous abortions, ectopic pregnancies, and placenta previa and may increase risks of behavioral disorders in childhood. Smoking during pregnancy will continue to be an important risk factor for maternal and fetal outcomes during pregnancy.

Adult↗

PubMed2004

Reasons for increasing trends in large for gestational age births.

OBJECTIVE: To describe the magnitude of change in the proportion of term and postterm (37 completed weeks or more) large for gestational age (LGA) infants between 1992-2001 in Sweden and to examine whether time trends in prevalence of LGA births can be explained by changes in maternal risk factors. METHODS: Using the population-based Swedish Birth Register, we analyzed data from 1992 through 2001 on births of women who delivered live, singleton, term infants without malformations (N = 874,163). Unconditional logistic regression was used to model the odds of LGA birth. RESULTS: Mean birth weight and proportions of LGA births and births 4,500 g or more rose during the period 1992 to 2001. An unadjusted analysis estimated that the risk of LGA birth increased by 23% over 10 years. However, the prevalence of overweight and obesity (body mass index of 25 or greater) increased from 25% to 36%, and the prevalence of smoking decreased from 23% to 11% during the same period. After adjusting trends in all covariates simultaneously, the association between risk of LGA birth and calendar year disappeared. CONCLUSION: The increasing proportions of LGA births over time is explained by concurrent increases in maternal body mass index and decreases in maternal smoking. With the increasing prevalence of overweight among adolescents and young women, the prevalence of LGA infants and associated risks may increase over time. LEVEL OF EVIDENCE: II-2

Adult↗

PubMed2004

Smoking and the risk of oral clefts: exploring the impact of study designs.

BACKGROUND: Maternal cigarette smoking is a suspected cause of oral clefts, although this association has not been firmly established. We used case-crossover, case-time-control, and bidirectional case-crossover designs to supplement findings from a case-control study of maternal smoking and oral clefts among offspring in a large birth registry. METHODS: Data are from the Swedish Medical Birth Registry. From 1983 through 1997 there were 678 recorded cases of cleft palate and 1175 cases of cleft lip with or without palate. Maternal smoking status was ascertained in early pregnancy. Controls for the case-control study were a random sample of infants born without a cleft; controls for the case-crossover designs were nonmalformed infants born to case mothers. RESULTS: Cleft palate was positively associated with maternal smoking in all study designs, whereas cleft lip with or without cleft palate was associated with smoking only in the case-control design. In the case-control design, the odds ratios for cleft palate were 1.2 (95% confidence interval = 1.0-1.5) for women who smoked 1 to 9 cigarettes per day and 1.4 (1.1-1.8) for women who smoked 10+ cigarettes per day. In the case-time-control analysis, the odds ratio for cleft palate with maternal smoking was 3.2 (1.3-7.4) and in the bidirectional case-crossover design, the odds ratio was 2.2 (1.1-4.1). CONCLUSIONS: An association between smoking and cleft palate was supported by all designs, whereas that between smoking and cleft lip with or without cleft palate was not. Case-only designs are a viable option in birth registries and may yield more information than a case-control design alone.

Adult↗

PubMed2004

Genetic influence on dystocia.

BACKGROUND: Dystocia-prolonged and difficult labor-is a common and worldwide problem during parturition. Epidemiological studies have suggested a familial aggregation. This study aimed to quantify the genetic influence (i.e. the heritability) on dystocia. METHODS: A retrospective study of all births in Sweden from 1973 through 1997 was undertaken. Data from the population-based Swedish Birth, Twin and National Family Registers were linked on an individual basis. In total, 2,539,534 births were analyzed. Relationships between sibling and mother-daughter pairs were established. The relative risk for dystocia was calculated. Model-fitting (Mx) was used to estimate the relative contribution of genetic and environmental factors for liability to dystocia. RESULTS: In all, 190,747 women were diagnosed with dystocia. Measures of familial similarity (relative risks and correlation of liability) for dystocia were higher in monozygotic than in dizygotic twins, other sibling pairs and mother-daughter pairs. Correlation of liability was also higher in full-sisters than in half-sisters. Model-fitting suggested that genetic effects accounted for 28%[95% confidence interval (CI) 21-32] of the susceptibility for dystocia. CONCLUSION: Dystocia is a complex disorder of poor uterine action that is influenced by a significant genetic component as well as environmental factors. The amount of genetic influence makes it interesting to study the gene expression in these patients. Detection of the genes related to dystocia might lead to better pathophysiological understanding of this condition and the possibility of detecting these mothers before parturition.

Adult↗

PubMed2004

The importance of genetic and environmental effects for pre-eclampsia and gestational hypertension: a family study.

OBJECTIVES: To determine the importance of genetic effects in the aetiology of pre-eclampsia and gestational hypertension and to investigate whether pre-eclampsia and gestational hypertension share genetic aetiology. DESIGN: Individual record linkage between the population-based Swedish Multi-Generation and the Medical Birth Registers. SETTING: Sweden. POPULATION: 1,188,207 births between 1987 and 1997 and their parents. METHODS: Similarities in relatives were measured by the number of pairs concordant and discordant for disease, the odds ratio (OR) and tetrachoric correlations. Estimates of genetic and environmental effect for gestational hypertension, pre-eclampsia and pregnancy-induced hypertension were calculated from structural equation model fitting. MAIN OUTCOME MEASURES: Pre-eclampsia and gestational hypertension. RESULTS: Full sisters and mother-daughters were more similar for pre-eclampsia (OR 3.3, 95% confidence interval [CI] 3.0-3.6 and OR 2.6, 95% CI 1.6-4.3, respectively) than half-sisters (maternal half-sisters OR 1.4, 95% CI 0.9-2.2 and paternal half-sisters OR 1.0, 95% CI 0.6-1.6). Full sisters and mother-daughters were also more similar for gestational hypertension than half-sisters. A full sister to a woman with pre-eclampsia also had a significantly increased risk of gestational hypertension (OR 2.5, 95% CI 2.2-2.8). In contrast, the risk for half-sisters was not increased. Model fitting suggested heritability estimates for pre-eclampsia of 31%, for gestational hypertension 20% and for pregnancy-induced hypertension 28%. CONCLUSIONS: There is a genetic component in the development of pre-eclampsia and gestational hypertension and the pattern of co-morbidity suggests that they may share part of their genetic aetiology. This could be important for studies of potential susceptibility genes for these diseases.

Environmental Health↗

PubMed2004

A prospective study of pregravid oral contraceptive use in relation to fetal growth.

OBJECTIVE: Because oral contraceptives are so widely used, any health consequences may have substantial public health implications. Whether pregravid oral contraceptives could affect subsequent pregnancies has not been adequately studied. The study objectives were to examine whether pregravid oral contraceptive use affects fetal growth and pregnancy hormone levels. DESIGN: A prospective study of pregnant women followed through pregnancy. SETTING: A major teaching hospital in Boston, USA. POPULATION: Two hundred and sixty Caucasian pregnant women, with a mean age of 31, and a parity of no more than two. Seventy-nine percent of the women were pregravid oral contraceptive users. METHODS: Exposure and covariate data were collected through structured questionnaires. Blood was drawn for hormonal analysis during the 16th and 27th gestational week. Information on pregravid oral contraceptive use included duration and recency of use, and oral contraceptive formulation. Multivariate regression models were used to examine the effect of pregravid oral contraceptive use on birth outcomes and the studied pregnancy hormones. MAIN OUTCOME MEASURES: Birthweight, placental weight, gestational age, pregnancy hormone levels of oestriol and progesterone at 16th and 27th gestational week. RESULTS: Adjusting for confounders, pregravid oral contraceptive use increased birthweight (mean difference =+207.3 g, 95% CI =+77.6 to +337.1) and placental weight (mean difference =+64.9 g, 95% CI =+13.0 to +116.9) compared with never use. Women with prior oral contraceptive use had higher levels of serum progesterone (P= 0.002) and oestriol (P= 0.12) at the 27th gestational week measurement. The effect on birthweight, placental weight and hormones was stronger among those using oral contraceptives in the previous year and those using a high progestin/high oestrogen potency preparation. CONCLUSIONS: Pregravid oral contraceptive use is positively associated with fetal growth, and this effect may be mediated through oestriol and progesterone.

Adolescent↗

PubMed2004

Premature death among teenage mothers.

OBJECTIVE: Some data suggest an association between teenage childbearing and premature death. Whether this possible increase in risk is associated with social circumstances before or after childbirth is not known. We studied premature death in relation to age at first birth, social background and social situation after first birth. DESIGN: Population-based cohort study. SETTING: Women born in Sweden registered in the 1985 Swedish Population Census. POPULATION: Swedish women born 1950-1964 who had their first infant before the age of 30 years (N= 460,434). METHODS: Information on the women's social background and social situation after first birth was obtained from Population Censuses. The women were followed up with regard to cause of death from December 1, 1990 to December 31, 1995. Mortality rate ratios and 95% confidence intervals (CI) were calculated. MAIN OUTCOME MEASURES: Mortality rates by cause of death. RESULTS: Independent of socio-economic background, teenage mothers faced an increased risk of premature death later in life compared with older mothers (rate ratio 1.6, 95% CI 1.4-1.9). The increased risk was most evident for deaths from cervical cancer, lung cancer, ischaemic heart disease, suicide, inflicted violence and alcohol-related diseases. Some, but not all, of these increases in risk were associated with the poorer social position of teenagers mothers. CONCLUSIONS: Teenage mothers, independent of socio-economic background, face an increased risk of premature death. Strategies to reduce teenage childbearing are likely to contribute to improved maternal and infant health.

Adolescent↗

PubMed2004

Preterm delivery, level of care, and infant death in sweden: a population-based study.

OBJECTIVE: To elucidate the role of level of care in combination with other perinatal risk factors for infant death in very preterm deliveries. DESIGN: Population-based cohort study. SETTING: Sweden, 1992-1998. SUBJECTS: Singleton infants (2285) born at 24 to 31 completed weeks of gestation to primiparous women. MAIN OUTCOME MEASURE: Infant mortality. RESULTS: The rate of infant mortality increased from 5% among infants born at 31 weeks' gestation to 56% among infants born at 24 weeks' gestation. Compared with infants born at university hospitals, the unadjusted odds ratio (OR) of infant death was 0.70 (95% confidence interval [CI]: 0.54-0.90) among infants delivered at general hospitals. However, after adjustment, the OR of infant death shifted to 1.33 (95% CI: 0.88-2.02) for preterm births at general hospitals. This shift was primarily due to different gestational age distributions in regional and general hospitals. Among infants born at 24 to 27 weeks' gestation, infant mortality rates were 23% (87 deaths) in university hospitals and 32% (73 deaths) in general hospitals, giving an adjusted OR of 2.00 for general versus university hospitals (95% CI: 1.15-3.49). The risk of death at 24 to 27 weeks' gestation in general hospitals was increased specifically in pregnancies with placental complications. CONCLUSION: Taking obstetric complications into account, there is an excess mortality risk among extremely preterm infants born at general hospitals.

Delivery, Obstetric↗

PubMed2004

Maternal smoking and childhood leukemia and lymphoma risk among 1,440,542 Swedish children.

Possible in utero effects of maternal smoking on hemopoietic cancer in the offspring have been addressed previously, although the results are inconclusive. In this investigation, we take advantage of population-based registers in Sweden to examine maternal smoking during pregnancy and childhood risk of leukemia and lymphoma. Prospective data were available from 1,440,542 Swedish children born between 1983 and 1997. Proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) controlling for potential confounders. In the study base, 750 hemopoietic cancers occurred across 11 million person-years. Incidence rates per 100,000 person-years were 4.7 for acute lymphocytic leukemia (ALL), 0.45 for acute myelogenous leukemia, and 0.76 for non-Hodgkin's lymphoma. Maternal smoking was associated with a lower risk of ALL (HR, 0.73; 95% CI, 0.58-0.91). On the other hand, there was a higher risk of acute myelogenous leukemia (HR, 1.41; 95% CI, 0.74-2.67) particularly among heavy (> or =10 cigarettes per day) smokers (HR, 2.28; 95% CI, 1.05-4.94). The data also suggested a small excess risk of non-Hodgkin's lymphoma (HR, 1.25; 95% CI, 0.76-2.04). Evidence from this large cohort suggests that maternal smoking affects the risk of childhood leukemia and lymphoma in the offspring. The Swedish registries provide unique opportunities to examine this research question, with a design inherently free of selection and recall biases. The apparent protective effect with ALL needs to be explored further and in no way supports maternal smoking as beneficial, given its adverse association with common pregnancy outcomes.

Age Factors↗