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Offspring number, pregnancy, and risk of a first clinical demyelinating event: the AusImmune Study.

Abstract

OBJECTIVE
To examine the association between past pregnancy, offspring number, and first clinical demyelination risk.
METHODS
Cases (n = 282) were aged 18-59 years with a first clinical diagnosis of CNS demyelination (first clinical demyelinating event [FCD]) and resident within 1 of 4 Australian centers (from latitudes 27° south to 43° south) from 2003 to 2006. Controls (n = 542) were matched to cases on age, sex, and study region, without first clinical diagnosis of CNS demyelination.
RESULTS
Higher offspring number was associated with FCD risk among women (p < 0.001) but not men (p = 0.71); difference in effect; p = 0.001. Among women, higher parity was associated with reduced risk of FCD (adjusted odds ratio 0.51 [95% confidence interval 0.36, 0.72] per birth) with a similar magnitude of effect observed among classic first demyelinating events (adjusted odds ratio 0.47 [95% confidence interval 0.29, 0.74]). The apparent beneficial effect of higher parity was also evident among parous women only (p < 0.001). Among cases, a clear female excess was evident for those with low but not high (4 or more) offspring number. Factors such as human leukocyte antigen DR15 genotype did not appear to modify the association between higher parity and a reduced FCD risk among women.
CONCLUSIONS
These findings are consistent with a cumulative beneficial effect of pregnancy. Temporal changes toward an older maternal age of parturition and reduced offspring number may partly underlie the increasing female excess among MS cases over time.

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  • Authors

    Ponsonby AL, Lucas RM, van der Mei IA, Dear K, Valery PC, Pender MP, Taylor BV, Kilpatrick TJ, Coulthard A, Chapman C, Williams D, McMichael AJ, Dwyer T

    Institution

    Murdoch Childrens Research Institute, Melbourne, Australia. anne-louise.ponsonby@mcri.edu.au

    Source

    Neurology 78:12 2012 Mar 20 pg 867-74

    MeSH

    Abortion, Spontaneous
    Adolescent
    Adult
    Australia
    Autoimmune Diseases
    Confidence Intervals
    DNA
    Data Interpretation, Statistical
    Demyelinating Diseases
    Female
    Genotype
    HLA-DR Antigens
    Humans
    Male
    Menarche
    Middle Aged
    Odds Ratio
    Parity
    Pregnancy
    Pregnancy Complications
    Questionnaires
    Risk Assessment
    Risk Factors
    Sex Factors
    Young Adult

    Pub Type(s)

    Journal Article
    Multicenter Study
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22402857