| 1. |
- Opdahl, S., et al.
(författare)
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Risk of hypertensive disorders in pregnancies following assisted reproductive technology: a cohort study from the CoNARTaS group
- 2015
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Ingår i: Human Reproduction. - : Oxford University Press (OUP). - 0268-1161 .- 1460-2350. ; 30:7, s. 1724-1731
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Tidskriftsartikel (refereegranskat)abstract
- STUDY QUESTION: Is the risk of hypertensive disorders in pregnancies conceived following specific assisted reproductive technology (ART) procedures different from the risk in spontaneously conceived (SC) pregnancies? SUMMARY ANSWER: ART pregnancies had a higher risk of hypertensive disorders, in particular following cryopreservation, with the highest risk seen in twin pregnancies following frozen-thawed cycles. WHAT IS KNOWN ALREADY: The risk of hypertensive disorders is higher in ART pregnancies than in SC pregnancies. The increased risk maybe partly explained by multiple pregnancies and underlying infertility, but a contribution from specific ART procedures has not been excluded. STUDY DESIGN, SIZE, DURATION: Population-based cohort study, including sibling design with nationwide data from health registers in Sweden, Denmark and Norway. PARTICIPANTS/MATERIALS, SETTING, METHODS: All registered ART pregnancies and a sample of SC pregnancies with gestational age >= 22 weeks from 1988 to 2007 were included. ART singleton pregnancies (n = 47 088) were compared with SC singleton pregnancies (n = 268 599), matched on parity and birth year. ART twin pregnancies (n = 10 918) were compared with SC twin pregnancies (46 674). We used logistic regression to estimate adjusted odds ratios and risk differences for hypertensive disorders in pregnancies following IVF, ICSI and fresh or frozen-thawed cycles. We also compared freshand frozen-thawed cycles within mothers who had conceived following both procedures using conditional logistic regression (sibling analysis). MAIN RESULTS AND THE ROLE OF CHANCE: Hypertensive disorders were reported in 5.9% of ART singleton and 12.6% of ART twin pregnancies. Comparing singleton pregnancies, the risk of hypertensive disorders was higher after all ART procedures. The highest risk in singleton pregnancies was seen after frozen-thawed cycles [risk 7.0%, risk difference 1.8%, 95% confidence interval (CI) 1.2-2.8]. Comparing twin pregnancies, the risk was higher after frozen-thawed cycles (risk 19.6%, risk difference 5.1%, 95% CI 3.0-7.1), but not after fresh cycles. In siblings, the risk was higher after frozen-thawed cycles compared with fresh cycles within the same mother (odds ratio 2.63, 95% CI 1.73-3.99). There were no clear differences in risk for IVF and ICSI. LIMITATIONS, REASONS FOR CAUTION: The number of ART siblings in the study was limited. Residual confounding cannot be excluded. In addition, we did not have information on all SC pregnancies in each woman's history, and could therefore not compare risk in ART versus SC pregnancies in the same mother. WIDER IMPLICATIONS OF THE FINDINGS: Pregnancies following frozen-thawed cycles have a higher risk of hypertensive disorders, also when compared with fresh cycle pregnancies by the same mother. The safety aspects in frozen-thawed cycles merit further attention. STUDY FUNDING/COMPETING INTEREST(S): Funding was received from the European Society for Human Reproduction and Embryology, the University of Copenhagen, the Danish Agency for Science, Technology and Innovation, the Nordic Federation of Societies of Obstetrics and Gynecology and the Liaison Committee between the Central Norway Regional Health Authority and the Norwegian University of Science and Technology. None of the authors has any competing interests to declare.
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| 2. |
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| 3. |
- Alm, Bernt, 1951, et al.
(författare)
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A case-control study of smoking and sudden infant death syndrome in the Scandinavian countries, 1992 to 1995. The Nordic Epidemiological SIDS Study.
- 1998
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Ingår i: Archives of disease in childhood. - 1468-2044. ; 78:4, s. 329-34
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Tidskriftsartikel (refereegranskat)abstract
- To establish whether smoking is an independent risk factor for sudden infant death syndrome (SIDS), if the effect is mainly due to prenatal or postnatal smoking, and the effect of smoking cessation.The analyses were based on data from the Nordic epidemiological SIDS study, a case-control study with 244 cases and 869 controls. Odds ratios were computed by conditional logistic regression analysis.Smoking emerged as an independent risk factor for SIDS, and the effect was mainly mediated through maternal smoking in pregnancy (crude odds ratio 4.0 (95% confidence interval 2.9 to 5.6)). Maternal smoking showed a marked dose-response relation. There was no effect of paternal smoking if the mother did not smoke. Stopping or even reducing smoking was beneficial. SIDS cases exposed to tobacco smoke were breast fed for a shorter time than non-exposed cases, and feeding difficulties were also more common.Smoking is an independent risk factor for SIDS and is mainly mediated through maternal smoking during pregnancy. Stopping smoking or smoking less may be beneficial in reducing the risk of SIDS.
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| 4. |
- Alm, Bernt, 1951, et al.
(författare)
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Breast feeding and the sudden infant death syndrome in Scandinavia, 1992-95.
- 2002
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Ingår i: Archives of disease in childhood. - : BMJ. - 1468-2044 .- 0003-9888. ; 86:6, s. 400-2
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Tidskriftsartikel (refereegranskat)abstract
- To assess the effects of breast feeding habits on sudden infant death syndrome (SIDS).The analyses are based on data from the Nordic Epidemiological SIDS Study, a case-control study in which parents of SIDS victims in the Scandinavian countries between 1 September 1992 and 31 August 1995 were invited to participate, each with parents of four matched controls. The odds ratios presented were computed by conditional logistic regression analysis.After adjustment for smoking during pregnancy, paternal employment, sleeping position, and age of the infant, the adjusted odds ratio (95% CI) was 5.1 (2.3 to 11.2) if the infant was exclusively breast fed for less than four weeks, 3.7 (1.6 to 8.4) for 4-7 weeks, 1.6 (0.7 to 3.6) for 8-11 weeks, and 2.8 (1.2 to 6.8) for 12-15 weeks, with exclusive breast feeding over 16 weeks as the reference. Mixed feeding in the first week post partum did not increase the risk.The study is supportive of a weak relation between breast feeding and SIDS reduction.
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| 5. |
- Alm, Bernt, 1951, et al.
(författare)
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Caffeine and alcohol as risk factors for sudden infant death syndrome. Nordic Epidemiological SIDS Study.
- 1999
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Ingår i: Archives of disease in childhood. - : BMJ. - 1468-2044 .- 0003-9888. ; 81:2, s. 107-11
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Tidskriftsartikel (refereegranskat)abstract
- To assess whether alcohol and caffeine are independent risk factors for sudden infant death syndrome (SIDS).Analyses based on data from the Nordic epidemiological SIDS study, a case control study in which all parents of SIDS victims in the Nordic countries from 1 September 1992 to 31 August 1995 were invited to participate with parents of four controls, matched for sex and age at death. Odds ratios (ORs) were calculated by conditional logistic regression analysis.The crude ORs for caffeine consumption > 800 mg/24 hours both during and after pregnancy were significantly raised: 3.9 (95% confidence interval (CI), 1.9 to 8.1) and 3.1 (95% CI, 1.5 to 6.3), respectively. However, after adjustment for maternal smoking in 1st trimester, maternal age, education and parity, no significant effect of caffeine during or after pregnancy remained. For maternal or paternal alcohol use, no significant risk increase was found after adjusting for social variables, except for heavy postnatal intake of alcohol by the mother, where the risk was significantly increased.Caffeine during or after pregnancy was not found to be an independent risk factor for SIDS after adjustment for maternal age, education, parity, and smoking during pregnancy. Heavy postnatal but not prenatal intake of alcohol by the mother increased the risk.
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| 6. |
- Alm, Bernt, 1951, et al.
(författare)
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Changes in the epidemiology of sudden infant death syndrome in Sweden 1973-1996.
- 2001
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Ingår i: Archives of disease in childhood. - 1468-2044. ; 84:1, s. 24-30
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Tidskriftsartikel (refereegranskat)abstract
- From the early 1970s to the early 1990s, there was a significant rise in the incidence of sudden infant death syndrome (SIDS) in Scandinavia. Following the risk reducing campaign, the incidence has fallen to about the same level as in 1973.To identify the changes that have occurred in the epidemiology of SIDS.We compared the Swedish part of the Nordic Epidemiological SIDS Study (NESS), covering the years 1992-1995, with two earlier, descriptive studies during this period. To assess the changing effects of risk factors, we analysed data from the Medical Birth Registry of Sweden, covering the years 1973-1996.There was a predominance of deaths during weekends in the 1970s and 1990s. The seasonal variation was most notable in the 1980s. The proportion of young mothers decreased from 14% to 5%. Cohabitation (living with the biological father) was as frequent in the 1990s as in the 1970s. The prevalence of high parity, admissions to neonatal wards, low birth weight, prematurity, and multiple pregnancies were all increased in the 1990s compared to the 1970s. No significant change in the prevalence of previous apparent life threatening events was found. Deaths occurring in cars diminished from 10% to below 2%. In the data from the Medical Birth Registry of Sweden, there were significantly increased odds ratios after the risk reducing campaign of the risk factors smoking during early pregnancy and preterm birth. We could find no increased effects of maternal age, parity, or being small for gestational age over time. The rate of deaths at weekends remained increased; the median age at death fell from 90 to 60 days. Seasonal variation was less notable in the periods of low incidence.
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| 7. |
- Alm, Bernt, 1951, et al.
(författare)
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Vitamin A and sudden infant death syndrome in Scandinavia 1992-1995.
- 2003
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Ingår i: Acta paediatrica (Oslo, Norway : 1992). - : Wiley. - 0803-5253. ; 92:2, s. 162-4
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Tidskriftsartikel (refereegranskat)abstract
- To assess the effect of vitamin supplementation on the risk of sudden infant death syndrome (SIDS).The analyses are based on data from the Nordic Epidemiological SIDS Study, a case-control study in which parents of SIDS victims in the Scandinavian countries were invited to participate together with parents of four matched controls between 1 September 1992 and 31 August 1995. The odds ratios presented are computed by conditional logistic regression analysis.The crude odds ratio in Scandinavia for not giving vitamin substitution was 2.8 (95% CI (1.9, 4.3)). This effect was statistically significant in Norway and Sweden, which use A and D vitamin supplementation, but not in Denmark, where only vitamin D supplementation is given. The odds ratios remained significant in Sweden when an adjustment was made for confounding factors (OR 28.4, 95% CI (4.7, 171.3)).We found an association between increased risk of sudden infant death syndrome and infants not being given vitamin supplementation during their first year of life. This was highly significant in Sweden, and the effect is possibly connected with vitamin A deficiency. This effect persisted when an adjustment was made for potential confounders, includingsocioeconomic factors.
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| 8. |
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| 9. |
- Daltveit, A K, et al.
(författare)
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Circadian variations in sudden infant death syndrome: associations with maternal smoking, sleeping position and infections. The Nordic Epidemiological SIDS Study.
- 2003
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Ingår i: Acta paediatrica (Oslo, Norway : 1992). - 0803-5253. ; 92:9, s. 1007-13
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Tidskriftsartikel (refereegranskat)abstract
- To study circadian variation in the sudden infant death syndrome (SIDS) and possible associations with risk factors for SIDS.A questionnaire-based case-control study matched for place of birth, age and gender was conducted in Denmark, Norway and Sweden: The Nordic Epidemiological SIDS Study. The study comprised 244 SIDS victims and 869 control infants between September 1992 and August 1995. The main outcome was hour found dead.A significant circadian pattern was observed among the 242 SIDS victims with a known hour found dead, with a peak at 08.00-08.59 in the morning (n = 33). Of the SIDS victims, 12% were found dead at 00.00-05.59, 58% at 06.00-11.59, 21% at 12.00-17.59 and 9.0% at 18.00-23.59. When comparing night/morning SIDS and day/evening SIDS (found dead 00.00-11.59 and 12.00-23.59, respectively), the proportion of night/morning SIDS was high among infants of smoking mothers (81% vs 53%, p < 0.001), infants with a reported cold (82% vs 64%, p = 0.007) and infants sleeping side/supine (81% vs 60%, p < 0.001). No associations were observed between hour found dead and other sociodemographic risk factors for SIDS. Risk (odds ratio and 95% confidence interval) of night/morning SIDS and day/evening SIDS was 7.0 (4.5-10.9) and 1.5 (0.8-2.5), respectively, for maternal smoking, 2.2 (1.5-3.1) and 0.6 (0.3-1.3), respectively, if the infant had a reported cold, 3.7 (2.1-6.6) and 3.1 (1.1-8.4), respectively, if the infant was put to sleep in the side position (supine reference), and 11.0 (5.9-20.2) and 21.6 (7.6-60.8), respectively, if the infant was put to sleep in the prone position.The observed higher proportion of night/morning cases in SIDS if the mother smoked, if the infant was reported to have a cold and if the infant was sleeping side/supine may contribute to the understanding of some epidemiological characteristics of SIDS.
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| 10. |
- Daltveit, A K, et al.
(författare)
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Sociodemographic risk factors for sudden infant death syndrome: associations with other risk factors. The Nordic Epidemiological SIDS Study.
- 1998
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Ingår i: Acta paediatrica (Oslo, Norway : 1992). - 0803-5253. ; 87:3, s. 284-90
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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