Influence of maternal age at delivery and birth order on risk of type 1 diabetes in childhood: prospective population based family study. Bart's-Oxford Family Study Group.
OBJECTIVE
To examine the influence of parental age at delivery and birth order on subsequent risk of childhood diabetes.


METHODS
Prospective population based family study.


METHODS
Area formerly administered by the Oxford Regional Health Authority.


METHODS
1375 families in which one child or more had diabetes. Of 3221 offspring, 1431 had diabetes (median age at diagnosis 10.5 years, range 0.4-28.5) and 1790 remained non-diabetic at a median age of 16. 1 years.


METHODS
Disease free survival and hazard ratios for the development of type 1 diabetes in all offspring, assessed by Cox proportional hazard regression.


RESULTS
Maternal age at delivery was strongly related to risk of type 1 diabetes in the offspring; risk increased by 25% (95% confidence interval 17% to 34%) for each five year band of maternal age, so that maternal age at delivery of 45 years or more was associated with a relative risk of 3.11 (2.07 to 4.66) compared with a maternal age of less than 20 years. Paternal age was also associated with a 9% (3% to 16%) increase for each five year increase in paternal age. The relative risk of diabetes, adjusted for parental age at delivery and sex of offspring, decreased with increasing birth order; the overall effect was a 15% risk reduction (10% to 21%) per child born.


CONCLUSIONS
A strong association was found between increasing maternal age at delivery and risk of diabetes in the child. Risk was highest in firstborn children and decreased progressively with higher birth order. The fetal environment seems to have a strong influence on risk of type 1 diabetes in the child. The increase in maternal age at delivery in the United Kingdom over the past two decades could partly account for the increase in incidence of childhood diabetes over this period.
Diabetes and Metabolism, Division of Medicine, University of Bristol, Southmead Hospital, Bristol BS10 5NB.
P J
PJ
Bingley
I F
IF
Douek
C A
CA
Rogers
E A
EA
Gale
D000328:Adult; D001722:Birth Order; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology* / Q000401:mortality; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008423:Maternal Age; D015999:Multivariate Analysis; D010331:Paternal Age; D011446:Prospective Studies; D012306:Risk; D012737:Sex Factors; D016019:Survival Analysis