A large new study of Danish women has tied a mother's asthma during pregnancy to a higher risk for developing a wide range of childhood diseases among her offspring.
The finding does not broadly concern all mothers who have a history of asthma, but rather those who actually experience an asthma attack while pregnant.
The observation could lead to heightened scrutiny of asthma status during pregnancy, and increased efforts to better control the condition, the researchers suggested. It may also encourage more vigilant monitoring of children who are born to mothers whose pregnancy included asthma flare-ups.
"There were previous indications that maternal asthma during pregnancy is linked to foetal development and some selected diseases in the offspring," said study co-author Gunther Meinlschmidt. "However, we were surprised that maternal asthma during pregnancy appears to be related to such a broad range of different diseases in the offspring."
Diseases with increased risk included infection and parasitic illness, nervous and respiratory system complications, and diseases of the ear and skin.
"Potentially" increased risks for offspring which were not confirmed in a follow-up analysis included digestive diseases, endocrine and metabolic disorders, and malformations.
Meinlschmidt, with the division of clinical psychology and epidemiology in the department of psychology at the University of Basel, in Switzerland, and colleagues report their observations in the September issue of Pediatrics.
To explore the impact of asthma in the context of pregnancy, the authors crunched data collected by a nationwide Danish study concerning slightly fewer than 67 000 mothers who gave birth between 1996 and 2002.
About one-quarter were smokers, most were in generally good health, and most were middle class or relatively well off.
Overall, just over 6% of women had struggled with an asthmatic event during their pregnancy, a figure gleaned from maternal interviews conducted three times during and six months after the pregnancy.
In turn, all the children were tracked using statistics from the Danish National Hospital Register for the onset of a variety of medical problems up to an average age of 6.
The result: maternal asthma was associated with a higher risk for developing a wide array of childhood diseases among newborns. However, while the study found this association, it did not prove a cause-and-effect relationship.
"There are different types, causes and treatments of asthma," Meinlschmidt said, "so mothers should discuss individual strategies to reduce their asthma risk with their GPs or other health care providers, considering benefits and risks of asthma treatment for mother and offspring."
Dr Alan Baptist, an assistant professor and director of the University of Michigan's asthma program in Ann Arbor, Michigan, said that he was "not completely surprised" by the study findings.
"It's mostly in line with what we currently feel, which is that uncontrolled asthma can have multiple deleterious effects on the fetus and infant. But it's very important that this research was done so we can clarify the impact as children grow," Baptist said.
"And the bottom line," he continued, "is that it's very important that asthma is kept under very good control during pregnancy. Because, in fact, for about one-third of women with asthma, their asthma actually worsens with pregnancy."
Baptist, who was not involved with the new study, pointed out that there is a balancing act between avoiding asthma effects in the mother and protecting the unborn child.
"You always want to avoid meds when possible while pregnant because of the potential to affect the foetus," he acknowledged. "But what has been shown over and over again is that it's far worse to have uncontrolled asthma than any potential drug side effects," Baptist said.
"I would also emphasise the importance of regular follow-up care for women with asthma," he said. "That means a visit to your ob/gyn or an asthma specialist a minimum of once a month."
For more on asthma and pregnancy, visit the U.S. National Institutes of Health.