Friday August 17 1:14 PM ET
Study Links Mother's Age, Child's Diabetes Risk
By Suzanne Rostler

NEW YORK (Reuters Health) - A mother's age has no effect on her firstborn child's risk of developing type 1 diabetes, but may influence the risk that later siblings will have the disease, according to new study findings.

Researchers tracked the 1.4 million people born between 1974 and 1998 in Norway and identified 1824 cases of type 1 diabetes diagnosed between 1989 and 1998.

Among fourth-born children, diabetes risk increased by 43% with every 5-year increase in a mother's age, Dr. Lars C. Stene from Aker and Ulleval University Hospitals in Oslo, Norway, and colleagues report. They also found an association between a mother's age and diabetes risk among second and other later-born children, but not among oldest siblings.

Both environmental and biologic factors may explain the findings, Stene's team notes in the August 18th issue of the British Medical Journal. Biologically, the interaction between the fetal and maternal immune systems may change with each pregnancy in a way that influences diabetes risk. Type 1 diabetes is an autoimmune disorder in which the body attacks the insulin-producing cells of the pancreas.

But infant feeding practices, newborn care and exposure to infections can vary with a mother's age and the number of children she already has, and these factors could also influence diabetes risk, the authors suggest.

At least one study has found that children who attend day care centers and are assumed to be exposed to more infections have a lower risk for type 1 diabetes, the report indicates. "One of the important implications of our (study) is that the risk of diabetes seems to vary with non-genetic factors," Stene told Reuters Health. "Up to now, only specific genes have convincingly been shown to predict risk to some extent in healthy individuals."

He cautioned that mothers should not be concerned, however, since the overall risk of developing type 1 diabetes before age 15 for an average newborn, at least in Norway, is 0.4%. Further studies should investigate possible reasons for the relationship, he added, as well as the relationship between the timing of successive pregnancies and immunologic factors in mothers.

In other findings, the risk of diabetes for subsequent children decreased when the mother was young. Second and later children born to mothers aged 20 to 24 years had an 18% lower risk of diabetes compared with firstborn children, the investigators found.

The researchers found no significant association between a father's age and the risk of type 1 diabetes.