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


Ponsonby, AL and Lucas, RM and van der Mei, IA and Dear, K and Valery, PC and Pender, MP and Taylor, BV and Kilpatrick, TJ and Coulthard, A and Chapman, C and Williams, D and McMichael, AJ and Dwyer, T, Offspring number, pregnancy, and risk of a first clinical demyelinating event: The AusImmune Study, Neurology, 78, (12) pp. 867-874. ISSN 0028-3878 (2012) [Refereed Article]

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Copyright 2012 AAN Enterprises, Inc.

DOI: doi:10.1212/WNL.0b013e31824c4648


Objective: To examine the association between past pregnancy, offspring number, and first clinical demyelination risk.

Methods: Cases (n = 282) were aged 1859 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.

Item Details

Item Type:Refereed Article
Research Division:Health Sciences
Research Group:Epidemiology
Research Field:Epidemiology not elsewhere classified
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:van der Mei, IA (Professor Ingrid van der Mei)
UTAS Author:Taylor, BV (Professor Bruce Taylor)
ID Code:78838
Year Published:2012
Web of Science® Times Cited:99
Deposited By:Menzies Institute for Medical Research
Deposited On:2012-07-30
Last Modified:2017-11-02
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