title: Infertility, infertility treatment, and mixed-handedness in children.
abstract: BACKGROUND
  Mixed-handedness, which may reflect atypical brain laterality, has been linked to a number of medical conditions as well as prenatal stress.
  
  
  OBJECTIVE
  The aim of the study was to examine whether infertility or infertility treatment was associated with an increased risk of mixed-handedness in children. STUDY DESIGN, SUBJECTS AND OUTCOME MEASURES: We used data from three population-based birth cohorts in Denmark: the Aalborg-Odense Birth Cohort (1984-1987), the Aarhus Birth Cohort (1990-1992) and the Danish National Birth Cohort (1996-2002) (N=7728, 5720 and 29486, respectively). Data on time to pregnancy and infertility treatment were collected during pregnancy. Handedness was reported in a follow-up questionnaire when the children were at least 7years old. Children were categorized as mixed-handed if their mothers reported that they used both hands equally.
  
  
  RESULTS
  Children born after infertility treatment, particularly intrauterine insemination, had a higher risk of being mixed-handed compared to children of fertile couples with a time to pregnancy </=12months (odds ratio 1.41, 95% confidence interval 1.09-1.82). Children of couples with unplanned pregnancies, particularly after an oral contraceptives failure, were also more likely to be mixed-handed. There was no association between a long waiting time to pregnancy and mixed-handedness in children.
  
  
  CONCLUSIONS
  Children born after infertility treatment, particularly intrauterine insemination, and children exposed to oral contraceptives during early gestation may have a higher risk of being mixed-handed.
authors.affiliation: The Danish Epidemiology Science Centre, Department of Epidemiology, School of Public Health, University of Aarhus, Bartholins Allé 2, 8000 Aarhus C, Denmark. zjl@soci.au.dk
authors.forename: Jin Liang
authors.initials: JL
authors.lastname: Zhu
authors.forename: Carsten
authors.initials: C
authors.lastname: Obel
authors.forename: Olga
authors.initials: O
authors.lastname: Basso
authors.forename: Bodil Hammer
authors.initials: BH
authors.lastname: Bech
authors.forename: Tine Brink
authors.initials: TB
authors.lastname: Henriksen
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D003276:Contraceptives, Oral / Q000009:adverse effects; D003718:Denmark / Q000453:epidemiology; D005260:Female; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007246:Infertility / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology*; D027724:Reproductive Techniques, Assisted; D012307:Risk Factors
chemical_list: D003276:Contraceptives, Oral