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Jørn Olsen

Publications and source records attributed to Jørn Olsen.

At least 19 recordsLinked to original sources
PubMed2007

Infertility, infertility treatment and twinning: the Danish National Birth Cohort.

BACKGROUND: We have previously observed that an increasing time to pregnancy (TTP) is associated with a reduced frequency of twin deliveries in couples not receiving infertility treatment. By using updated information, we assessed the frequencies of dizygotic (DZ) and monozygotic (MZ) twin deliveries as a function of infertility (TTP > 12 months), as well as infertility treatment. METHODS: From the Danish National Birth Cohort (1997-2003), we identified 51 730 fertile couples with TTP 12 months and 5163 infertile couples who conceived after treatment. Information on zygosity, available for part of the cohort (1997-2000), was based on standardized questions on the similarities between the twins at the age of 3-5 years. RESULTS: Compared with fertile couples, the frequency of DZ twin deliveries was lower for infertile couples conceiving naturally (odds ratio 0.4, 95% confidence interval 0.2-0.7) and was much higher for infertile couples conceiving after treatment (17.3, 14.4-20.7). The frequency of DZ twin deliveries decreased with TTP in untreated couples, whereas the frequency of MZ twin deliveries remained constant. CONCLUSIONS: The frequency of DZ twin deliveries decreased with TTP and substantially increased with infertility treatment, whereas MZ twin deliveries remained substantially unchanged.

Adult↗
PubMed2007

Use of phenytoin, phenobarbital, or diazepam during pregnancy and risk of congenital abnormalities: a case-time-control study.

PURPOSE: Case-control studies are often used to examine putative teratogenic drug effects during organogenesis but these studies are subject to confounding by indication, recall, and participation bias. The case-time-control approach is less susceptible to these sources of bias. We studied congenital abnormalities following exposure to phenytoin, phenobarbital, and diazepam in early pregnancy, i.e., second and third month, compared to mid-pregnancy, i.e., fifth and sixth month of pregnancy. METHODS: We analyzed data from the Hungarian Case-Control Surveillance of Congenital Abnormalities (1980-1996) in a case-time-control study. RESULTS: The study included 22 843 children with congenital abnormalities (cases) and 38 151 children with no abnormalities (controls). Overall, odds ratio (OR) for congenital abnormalities after exposure to one of the three drugs in early pregnancy was 1.2 (95% confidence interval (CI): 1.0-1.4). Among children exposed to phenytoin OR for congenital abnormalities was 3.7 (95%CI: 0.3-49.6), for children exposed to phenobarbital the OR was 1.1 (95%CI 0.7-1.7), and for diazepam, OR for congenital abnormalities was 1.2 (95%CI: 1.0-1.4). CONCLUSIONS: The associations we found between the drugs examined and congenital abnormalities were either only borderline significant or not statistically significant. The case-time-control study provides an interesting way of using existing case-control data to study rare side effect of drugs taken during pregnancy.

Abnormalities, Drug-Induced↗
PubMed2007

Cryptorchidism according to maternal gestational smoking.

BACKGROUND: It has been suggested that maternal smoking during pregnancy is a risk factor for low sperm counts and testicular cancer in the offspring. Cryptorchidism is associated with both of these disorders and might share causal mechanisms. METHODS: We used prospective information on prenatal exposures and obstetric information on the birth of 5716 boys, collected from 1984 to 1987. During the 16-19 years of follow-up, 270 cases of cryptorchidism were diagnosed, and 185 of these boys underwent orchiopexy. RESULTS: Compared with nonsmokers, the adjusted risk ratio for being diagnosed with cryptorchidism was 1.1 (95% confidence interval = 0.8-1.6) if the mothers smoked 10-19 cigarettes/day and 2.3 (1.1-5.0) if they smoked > or = 20 cigarettes/day. The risk ratios for orchiopexy were 1.4 (0.9-2.1) and 1.8 (0.6-5.0), respectively. CONCLUSION: An excess risk of cryptorchidism was observed among sons of mothers who smoked 10 cigarettes or more per day during pregnancy. In recognition of the limited power of this study, the findings should be replicated in larger cohorts.

Adult↗
PubMed2006

Invited commentary: the art of making questionnaires better.

A paper by Schilling et al. (Am J Epidemiol 2006;164:1141-4) addresses a crucial issue for epidemiologists: limited peer access to questionnaires. This limited access hampers the ability to evaluate and improve the questions used by investigators and, in turn, the quality of some of the self-reported data. The authors of this commentary analyzed recent publications in core epidemiology journals, finding that self-reported data were used in 64% of articles, but key questions were seldom printed in the article (9%), and open access to complete questionnaires (16%) was rarely provided. Only 47% of articles even discussed validation; of these, only 67% actually validated questions used in the study. The authors join Schilling et al. in making recommendations to improve questionnaire access and collaboration. A first step, proposed before, involves investigators posting their questionnaires on a website concurrently with publication of their article. Journal editors should require online access to full questionnaires for published articles and inclusion of key questions within the article when possible. Funding agencies should take the lead in increasing access and collaboration by developing a searchable database.

Access to Information↗
PubMed2006

Epilepsy and febrile seizures in children of treated and untreated subfertile couples.

BACKGROUND: Only few studies have addressed the long-term neurological outcomes of children born by subfertile couples. We studied the risk of epilepsy and febrile seizures in children of treated and untreated subfertile couples. METHODS: The study included 83 194 live singletons born by mothers who took part in the Danish National Birth Cohort (DNBC). Information on time to pregnancy (TTP) and infertility treatment was reported by the mothers in computer-assisted telephone interviews. Data on epilepsy and febrile seizures were extracted from the Danish National Hospital Register. RESULTS: Overall, children of subfertile couples (TTP > 12 months) had a 51% higher risk of epilepsy [incidence rate ratio (IRR): 1.51; 95% confidence interval (95% CI): 1.17-1.94] compared with children of couples with a TTP of 0-5 months. The corresponding estimates were 1.71 (95% CI: 1.21-2.42) if the couples had received infertility treatment and 1.38 (95% CI: 1.00-1.89) if they conceived spontaneously. Children of subfertile couples did not have a higher risk of febrile seizures except for those who received hormonal treatment (HT) with or without intrauterine insemination (IRR = 1.37; 95% CI: 1.14-1.66). CONCLUSIONS: Children of subfertile couples had a slightly increased risk of epilepsy, and the risk tended to be higher for children of couples who received infertility treatment. Whether this reflects side effects of treatment or severity of subfecundity is not known.

Child↗
PubMed2006

Infertility, infertility treatment, and congenital malformations: Danish national birth cohort.

OBJECTIVES: To examine whether infertile couples (with a time to pregnancy of > 12 months), who conceive naturally or after treatment, give birth to children with an increased prevalence of congenital malformations. DESIGN: Longitudinal study. SETTING: Danish national birth cohort. PARTICIPANTS: Three groups of liveborn children and their mothers: 50,897 singletons and 1366 twins born of fertile couples (time to pregnancy < or = 12 months), 5764 singletons and 100 twins born of infertile couples who conceived naturally (time to pregnancy > 12 months), and 4588 singletons and 1690 twins born after infertility treatment. MAIN OUTCOME MEASURES: Prevalence of congenital malformations determined from hospital discharge diagnoses. RESULTS: Compared with singletons born of fertile couples, singletons born of infertile couples who conceived naturally or after treatment had a higher prevalence of congenital malformations-hazard ratios 1.20 (95% confidence interval 1.07 to 1.35) and 1.39 (1.23 to 1.57). The overall prevalence of congenital malformations increased with increasing time to pregnancy. When the analysis was restricted to singletons born of infertile couples, babies born after treatment had an increased prevalence of genital organ malformations (hazard ratio 2.32, 1.24 to 4.35) compared with babies conceived naturally. No significant differences existed in the overall prevalence of congenital malformations among twins. CONCLUSIONS: Hormonal treatment for infertility may be related to the occurrence of malformations of genital organs, but our results suggest that the reported increased prevalence of congenital malformations seen in singletons born after assisted reproductive technology is partly due to the underlying infertility or its determinants. The association between untreated infertility and congenital malformations warrants further examination.

Cohort Studies↗
PubMed2006

Stillbirth and slow metabolizers of caffeine: comparison by genotypes.

BACKGROUND: Cytochrome P4501A2 (CYP1A2) and N-acetyltransferase 2 (NAT2) are key enzymes in the metabolism of caffeine. The polymorphism of these genes facilitates the detection of fast and slow metabolizers, and if caffeine is causally related to stillbirth, we expect slow metabolizers to have a higher risk of stillbirth at any given intake of caffeine. Gluthatione S-transferase alpha1 (GSTA1) may also be active in the metabolism of caffeine as it conjugates glutathione to aromatic amines. Our study, therefore, included analyses of the association between GSTA1 and stillbirth. METHODS: A nested case non-case study among women who participated in the Danish National Birth Cohort: 142 cases of singleton stillbirths and 157 controls of singleton live births. RESULTS: Slow oxidizer status (CYP1A2), slow acetylator status (NAT2), and low activity of GSTA1 were not individually associated with the risk of stillbirth [odds ratio (OR) = 1.06, 95% confidence interval (95% CI) 0.67-1.67, OR = 0.95, 95% CI 0.60-1.51, and OR = 1.42, 95% CI 0.88-2.28, respectively]. We did, however, observe that subjects with a combination of slow CYP1A2, slow NAT2, and low GSTA1 genes had almost a 2-fold risk of stillbirth compared with subjects with other combinations of genotypes. CONCLUSIONS: We found no link between any single genotype and the risk of stillbirth. An association between a combination of genotypes and stillbirth was discovered. Caffeine may be causally related to stillbirth, but larger studies using Mendelian randomization are needed to verify this.

Acetyltransferases↗
PubMed2006

Associations between socio-economic factors and the use of prescription medication during pregnancy: a population-based study among 19,874 Danish women.

OBJECTIVE: To examine the association between socio-economic factors and use of prescription medication during pregnancy in a population of Danish women. METHODS: This was a population-based cohort study. Using record linkage from public administrative registries, we described the use of prescription medication during pregnancy and the financial and educational resources for each pregnant woman in the cohort. RESULTS: The analyses included all 19,874 primiparous women delivering singletons in North Jutland county, Denmark, in 1991-1998. We identified 24,243 prescriptions filled by the women during their pregnancies. The highest overall prescription medication use was among women with basic schooling (OR 1.3; 95% CI 1.2-1.4), and lowest among women with the highest education (OR: 0.8; 95% CI 0.7-0.9) compared with women who had vocational education. Stratified analysis of therapeutic subgroups revealed that socio-economic factors were associated with the use of anti-infective and anti-asthmatic medications during pregnancy. CONCLUSION: Maternal educational level, and to a lesser degree household income, paternal educational level and cohabitation status, was associated with the use of prescription medication during pregnancy. However, the analyses did not take into account important clinical variables such as maternal illness, and the results could be affected by differential misclassification of exposure information, by confounding or chance.

Adult↗
PubMed2006

Reproductive health indicators in the European Union: The REPROSTAT project.

Our objective was to develop a set of indicators for monitoring and describing reproductive health in the European Union (EU) that reflect common concerns of the different Member States. Ideally, the indicators would possibly draw upon existing data sources. The REPROSTAT project: (i) conducted a review of existing recommendations on reproductive health indicators; (ii) suggested a set of initial indicators in consultation with representatives from relevant outside agencies and organisations; and (iii) invited 200 reproductive health experts throughout Europe to review the provisional set of indicators. The feasibility of using the REPROSTAT indicators was tested for two countries, Italy and Germany. A final set of 13 core indicators was developed, as well as another recommended indicator and four that needed further development. The pilot use of the indicators in Italy and Germany provided useful information about availability of data in different Member States. The REPROSTAT project developed a set of reproductive health indicators believed to be of relevance for planning, prevention, and caring within the EU. Further, harmonisation of data from different Member States will be needed if the benefits of these indicators are to be fully realised.

Abortion, Induced↗
PubMed2006

Prenatal risk indicators of a prolonged pregnancy. The Danish Birth Cohort 1998-2001.

BACKGROUND: Few prenatal risk factors of prolonged pregnancy, a pregnancy of 42 weeks or more, are known. The objective was to examine whether sociodemographic, reproductive, toxicologic, or medical health conditions were associated with the risk of prolonged pregnancy. METHODS: Data from the Danish Birth Cohort in Denmark were used. Interview data from 53,392 participants with live-born singleton deliveries in the period 1998-2001 were available at the time of this study. The participants were interviewed by telephone at 12 and 30 weeks' gestation, and 6 and 18 months after delivery. Statistical analyses were done using logistic regression. RESULTS: Women with a pre-pregnancy body mass index of 25 kg/m2 or more had a high risk of prolonged pregnancy. If the pre-pregnancy body mass index was 35 kg/m2 or more the odds ratio was 1.52 (95% CI 1.28-1.82). Nulliparity also increased the risk of prolonged pregnancy (OR (95% CI) = 1.35 (1.27-1.44)). CONCLUSIONS: The risk of post-term delivery was high in women with a pre-pregnancy body mass index of 25 kg/m2 or more, and in nulliparous women.

Adolescent↗
PubMed2006

Bacterial vaginosis in early pregnancy is associated with low birth weight and small for gestational age, but not with spontaneous preterm birth: a population-based study on Danish women.

OBJECTIVE: To analyze the association between bacterial vaginosis (BV) in early pregnancy and preterm birth, low birth weight (LBW) and small for gestational age (SGA) in a Danish population. METHODS: A geographically defined population-based prospective study of Danish-speaking pregnant women over18 years of age enrolled before week 24 and followed until delivery. BV was diagnosed by Amsel's clinical criteria at enrolment. RESULTS: At enrolment, 13.7% had BV. BV was not associated with an increased risk of spontaneous preterm birth (crude OR 0.8 (0.5-1.5)). Nulliparity was found to affect birth weight to such a degree that this variable was used for stratification. In nulliparous women BV was associated with LBW (adj. OR 4.3 (1.5-12)) and SGA (adj. OR 1.6 (0.7-3.1)) compared to nulliparous without BV. No such associations were seen for multiparous women with BV. CONCLUSIONS: BV was not associated with spontaneous preterm birth, but was associated with both LBW and SGA in nulliparous women.

Adolescent↗
PubMed2006

Apgar scores and long-term risk of epilepsy.

BACKGROUND: Low Apgar scores are associated with high risk of neonatal death, cerebral palsy, and mental retardation, but the association between Apgar scores and long-term risk of epilepsy remains unresolved. METHODS: We carried out a population-based cohort study of 1,538,732 live newborns in Denmark between 1 January 1978 and 31 December 2002 by using national registers. The Apgar scores at 1 or 5 minutes were recorded by midwives following standardized procedures. We obtained information on epilepsy by linking the cohort with the National Hospital Register. Cohort members were followed from birth until onset of epilepsy, death, emigration, or 31 December 2002, whichever came first. RESULTS: The incidence rate of epilepsy increased consistently with decreasing Apgar scores. The incidence rate of epilepsy was 628 per 100,000 person-years for those with 5-minute Apgar scores of 1 to 3 and 86 per 100,000 person-years for those with a score of 10; the resulting incidence rate ratio was 7.1 (95% confidence interval = 5.8-8.8). The incidence rate ratios of epilepsy associated with low Apgar scores were particularly high in early childhood but remained high into adulthood. The association did not change after excluding children with cerebral palsy, congenital malformations, or a parental history of epilepsy. CONCLUSIONS: Neonates with a suboptimal Apgar score have a higher risk of epilepsy that lasts into adult life. These findings suggest that prenatal or perinatal factors play a larger role in the etiology of epilepsy than has previously been recognized.

Adult↗
PubMed2006

Paternal age and Apgar scores of newborn infants.

BACKGROUND: New evidence suggests that advanced paternal age is a reproductive hazard, but we do not know whether paternal age affects the physical conditions of newborn infants as measured by the Apgar score. METHODS: We conducted a register-based cohort study of 70,347 couples and their first singleton infants by using data from the Danish Fertility Database (1980-1996). Information on Apgar score was obtained by linking the children to the National Birth Register. RESULTS: The odds ratio for having a baby with a 1-minute Apgar score of 1-3 was 1.64 (95% confidence interval = 1.08-2.48) for fathers 45 to 49 years of age and 1.49 (0.76-2.94) for fathers 50+ years compared with fathers 20 to 29 years (P for trend = 0.011). The risk of having a 5-minute Apgar score less than 7 increased among fathers 45+ years old (P for trend = 0.178). CONCLUSIONS: Our data suggest a modest effect of advanced paternal age on the Apgar score.

Adult↗