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Carsten Obel

Publications and source records attributed to Carsten Obel.

18 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↗
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

Cigarette smoking during pregnancy and hyperactive-distractible preschooler's: a follow-up study.

AIM: To study the association between intrauterine exposure to tobacco smoke and behavioural disorders in preschool children, primarily symptoms of inattention, hyperactivity and impulsivity but also hostile-aggressive and anxious-fearful symptoms. METHODS: We conducted a follow-up study in 1355 singletons born to Danish-speaking mothers. Information on smoking habits during pregnancy and other lifestyle factors was obtained from self-administered questionnaires filled in during second and third trimester. Approximately 3.5 years later, the parents provided information on their child's behaviour using the self-administered Preschool Behaviour Questionnaire. The children were categorized into three not mutually exclusive behaviour groups: hyperactive - distractible (13.6%), hostile-aggressive (4.6%), and anxious-fearful (6.4%) children. RESULTS: Compared with children of non-smokers, children born to women who smoked 10 or more cigarettes per day had a 60% increased risk of hyperactivity and distractibility perceived by the parents (OR 1.6; 95% CI 1.0-2.3; P < 0.05). The results were adjusted for maternal lifestyle factors and socioeconomic characteristics. Additional adjustment for perinatal factors and parental psychiatric hospitalization did not change the results substantially (OR 1.7; 95% CI 1.1-2.6). We found no statistically significant association between maternal smoking in pregnancy and hostile-aggressive and anxious-fearful behaviour in the offspring. CONCLUSION: Exposure to tobacco smoke in utero was associated with hyperactive-distractible behaviour in preschool children.

Child Behavior Disorders↗
PubMed2006

Gestational age and birth weight in relation to school performance of 10-year-old children: a follow-up study of children born after 32 completed weeks.

BACKGROUND: Children born extremely premature (<28 weeks) or with a very low birth weight (<1500 g) have a poorer school performance than children born at term with a normal birth weight. Much less is known about children of higher gestational ages and birth weights. We studied gestational age after 32 completed weeks and birth weight in relation to the child's school performance at the age of 10 years. METHODS: We performed a follow-up study of 5319 children born between January 1990 and June 1992. We got the information on birth weight and gestational age from birth registration forms; when the children were between 9 and 11 years of age, we gathered information about their school performance (reading, spelling, and arithmetic) from questionnaires completed by the parents and the children's primary school teachers. RESULTS: The association between birth weight and reading, as well as spelling and arithmetic disabilities, showed a graded relationship, with children who weighed <2500 g having the highest risks. Even children who weighed between 3000 and 3499 g had an increased risk of all 3 learning disabilities compared with children who weighed between 3500 and 4000 g. This association persisted after adjustment for potential cofounders and when the analyses were restricted to children born at term (39-40 weeks of gestation), suggesting that the association could not be explained by a low gestational age. Compared with children born at term, reading and spelling difficulties were more often found among children born at gestational age 33 to 36 weeks and 37 to 38 weeks, whereas there was no relation between gestational age and arithmetic difficulties. CONCLUSIONS: Gestational age and birth weight were associated with school performance in the 10-year-old child and the association extended into the reference range of both birth weight and gestational age.

Achievement↗
PubMed2005

The Danish National Hospital Register is a valuable study base for epidemiologic research in febrile seizures.

BACKGROUND AND OBJECTIVES: We examined the quality and completeness of the discharge diagnosis of febrile seizures in the Danish National Hospital Register (DNHR). METHODS: We invited all children born at the Department of Obstetrics, Aarhus University Hospital, Denmark, between January 1990 and April 1992, to participate in the study. We collected information on febrile seizures in March 2001 by mailing a questionnaire to the mothers. Reported febrile seizures were verified by telephone interviews or review of medical records. We linked the cohort to the DNHR by means of a unique civil registry number assigned to all Danish citizens at birth. Overall, 6,624 (73%) children participated in the study. RESULTS: We found that 323 (4.9%) children in the cohort had had febrile seizures, and 231 of those were registered in the DNHR (completeness: 71.5%, 95% CI: 66.3-76.4). Furthermore, we confirmed the diagnosis in 231 of 249 children registered with febrile seizures in the DNHR (predictive value of a positive registration: 92.8%, 95% CI: 88.8-95.7). CONCLUSION: The Danish National Hospital Register is a valuable tool for epidemiologic research in febrile seizures.

Child↗
PubMed2005

Smoking during pregnancy and the risk for hyperkinetic disorder in offspring.

OBJECTIVE: Maternal smoking during pregnancy may increase the risk for behavioral disorders. The aim of this study was to investigate the association between smoking during pregnancy and hyperkinetic and attention-deficit/hyperactivity disorder in the offspring in a large population-based study. METHODS: This study was designed as a nested case-control study. Data were obtained from Danish longitudinal registers and included 170 children with hyperkinetic disorder and 3765 population-based control subjects, who were matched by age, gender, and date of birth. Potential confounders, including newborn characteristics, socioeconomic status, and family history of psychiatric illnesses, were evaluated by conditional logistic regression analyses. RESULTS: Women who smoked during pregnancy had a 3-fold increased risk for having offspring with hyperkinetic disorder compared with nonsmokers. Socioeconomic factors and history of mental disorder in the parents or siblings seemed to confound the result to some extent (adjusted relative risk: 1.9; 95% confidence interval: 1.3-2.8). Adjustment for parental age or exclusion of children with low birth weight (<2500 g), preterm delivery (<37 weeks completed gestation), and Apgar scores <7 at 5 minutes revealed no changes in the results. Also, excluding children with conduct disorders or comorbid disorders revealed no change in the results. CONCLUSIONS: Our results showed an increased risk for hyperkinetic disorder in children of mothers who smoked during pregnancy. This could not be explained by newborn characteristics, parental socioeconomic status, family history of psychiatric hospitalizations or contact as outpatients, conduct disorders, or comorbidity.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

The Strengths and Difficulties Questionnaire in the Nordic countries.

BACKGROUND: The Strengths and Difficulties Questionnaire (SDQ) has been translated into the different Nordic languages between 1996 and 2003. During the past few years, SDQs have been completed for nearly 100,000 children and adolescents in population-based studies as well as in clinical samples. The largest studies have been performed in Norway and Denmark, and in these countries the diagnostic interview DAWBA has also been used in conjunction with the SDQ. AIMS: In addition to a brief overview of past and ongoing SDQ work in Sweden, Finland, Norway, Denmark, and Iceland, we present scale means and standard deviations from selected community studies with comparable age groups, including parental reports for 7, 9 and 11 year-old children and self-reports of 13 and 15 year-olds. CONCLUSIONS: The descriptive statistics suggest that the distributions of SDQ scores are very similar across the Nordic countries. Further collaborative efforts in establishing norms and evaluating the validity of the SDQ as a screening instrument are encouraged.

Adolescent↗
PubMed2004

Social risk factors as predictors for parental report of deviant behaviour in 3-year-old children.

The objective of this study was to examine whether social risk factors adjusted for gender and some well-known perinatal risk factors were related to parental descriptions of deviant behaviour in 3(1/2)-year-old children. The study was a prospective cohort study of 1345 mothers enrolled during early pregnancy. Parents answered a questionnaire and children's behavioural difficulties were categorized into the following groups; "hyperactive-distractible", "hostile-aggressive" and "anxious-fearful" following a modified Behar scale. The male gender was found to be related to a description of all kinds of deviant behaviour. Having a family member experiencing employment difficulties was the factor most closely related to "hyperactive-distractible" behaviour. Familial stress due to lack of time, experience of divorce and mothers in excess of 35 years at childbirth were found to be related to "hostile-aggressive" behaviour, but male gender was the most closely related. Social disadvantage was not found to be related to "anxious-fearful" behaviour.

Anxiety↗
PubMed2003

Psychological factors in pregnancy and mixed-handedness in the offspring.

Animal studies suggest that psychological factors may interfere with the development of brain asymmetry during gestation. We evaluated whether psychological exposure in pregnancy was associated with mixed-handedness in the offspring. In a follow-up design study, 824 Danish-speaking women with singleton pregnancies provided information on psychological distress and the occurrence of life events in the early second and third trimesters of pregnancy. Handedness of the children was based on maternal reports when the children were 3 years of age. Among the 419 males and 405 females, 7% and 5% respectively were mixed-handed whereas mixed-handedness was found in 3% of the parents. Psychological distress in the third trimester as well as higher levels of stressful life events were related to a higher prevalence of mixed-handedness in the offspring. About 16% of the women reported more than one life event in the third trimester of pregnancy and among the offspring of these women 11% were mixed-handed (odds ratio = 2.3; 95% confidence interval 1.2 to 4.4). Women who at the same time reported a high level of distress and stressful life events, had a three- to four-fold higher prevalence of mixed-handedness in their offspring.

Adult↗
PubMed2003

Stressful life events in pregnancy and head circumference at birth.

A strong association between stress in pregnancy and small head circumference in infants at birth was reported in 1994. This important finding has never been replicated. In a follow-up study of 4211 participants with singleton pregnancies, information on life events was collected twice during pregnancy and head circumference measured shortly after birth following standard procedures. No association was found between experienced or perceived stress as a result of life events during pregnancy and head circumference in the infants. In conclusion, stress in pregnancy may influence foetal brain development in many ways, but we found no support for an effect on the size of the brain as measured by head circumference at birth.

Birth Weight↗
PubMed2003

Maternal lifestyle factors in pregnancy risk of attention deficit hyperactivity disorder and associated behaviors: review of the current evidence.

OBJECTIVE: The purpose of this review was to examine the literature assessing the relationship between prenatal exposure to nicotine, alcohol, caffeine, and psychosocial stress during pregnancy to the risk of developing behavioral problems related to attention deficit hyperactivity disorder (ADHD) in childhood. METHOD: PubMed, MEDLINE, EMBASE, and PsycINFO were searched systematically. Studies using DSM diagnostic criteria and other validated diagnostic or screening instruments for ADHD and those examining ADHD symptoms were included. A narrative approach was used because the studies differed too much in methods and data sources to permit a quantitative meta-analysis. RESULTS: Twenty-four studies on nicotine (tobacco smoking), nine on alcohol, one on caffeine, and five on psychosocial stress were identified. All were published between 1973 and 2002. In spite of inconsistencies, the studies on nicotine indicated a greater risk of ADHD-related disorders among children whose mothers smoked during pregnancy. Contradictory findings were reported in the alcohol studies, and no conclusion could be reached on the basis of the caffeine study. Results from studies on psychological stress during pregnancy were inconsistent but indicated a possible modest contribution to ADHD symptoms in the offspring. Many studies suffered from methodological shortcomings, such as recall bias, crude or inaccurate exposure assessments, low statistical power, and lack of or insufficient control of confounders. A general lack of information on familial psychopathology also limited the interpretations. CONCLUSIONS: Exposure to tobacco smoke in utero is suspected to be associated with ADHD and ADHD symptoms in children. Other maternal lifestyle factors during pregnancy may also be associated with these disorders. Further studies are needed to reach conclusions.

Adolescent↗