THURSDAY, March 11, 2004 (HealthDayNews) -- Cold weather at birth is associated with an increased risk of diabetes, heart problems and poor lung function if the baby is born into a low-income family, a new British study finds.
The study of more than 4,000 women now in their 60s and 70s discovered that those born in the coldest months were more likely to develop coronary heart disease, breathing problems, high cholesterol levels and insulin resistance, says a report in the April issue of Heart by researchers at the University of Bristol.
The association between temperature at birth and later health problems was strongest for babies whose fathers were either unemployed or manual laborers and "was nonexistent in those from nonmanual social classes in childhood," the report says.
Clearly, "those most likely to have fewer resources and a lower standard of living were most likely to be affected by the cold," says Dr. Richard Mitchell, a research fellow at the University of Edinburgh Medical School and a member of the study team.
"Our study suggests that resources, in terms of things like housing quality and clothing, are an important buffer," Mitchell says. "Where resources are adequate for the environment, the environment poses no threat. When they're not so good, the environment gets a chance to affect the body much more."
In cold numbers, women born in the three most frigid months of the year were 24 percent more likely to have coronary heart disease later in life, the researchers say.
Weather is far from the whole story, Mitchell says, since "it's reasonable to assume that diet and lifestyle are more important."
"What's interesting about this work, though, is that we can still detect an influence of climate around the time of birth when the study subjects are very much older," he says.
The study results could help explain why some people are more vulnerable to heart disease than others, Mitchell says, since it "demonstrates one of many potential contributors to that risk."
The implications of the study for women who know they will give birth at the cold time of the year are "nothing different to the advice that's given now -- stay comfortably warm if possible," he says.
"If women have any concern about the right thing to do in pregnancy, they must ask their doctor," Mitchell says.
The study is unusual because it looks at the long-term effect of weather on health, says Joan Aron, a research associate at the Johns Hopkins School of Public Health who has done research on climate and health.
"Generally, people have looked for more immediate health problems, direct effects such as happen during heat waves," Aron says.
Finding a relationship between family status and health is not surprising, she says.
"Sixty years ago, if you lived in a poor household, that environment could probably affect your health," she says.