The greater the feelings of anxiety felt by mothers-to-be the greater the risk their child will develop the condition, according to the research.
More than 5 million people in Britain suffer from asthma, including more than a million children.
Researchers found that very anxious expectant mothers were 65 per cent more likely to have children who went on to develop asthma, in a study of more than 5,800 youngsters and their parents.
On average, mothers who felt stressed during pregnancy had a 17 per cent greater chance of having an asthmatic child.
Researchers at the University of Bristol followed the women from the early stages of their pregnancy until their children were 10 years old.
They also found that when expectant mothers experienced stress, it had an impact on their children's future health.
Those who felt themselves to be under pressure late in their pregnancy were more likely to have a child who developed asthma than women who experienced the same feeling in the early stages.
The scientists believe that the findings might be linked to a hormone which could affect the immune system.
They found that children whose mothers described themselves as very stressed during their pregnancy appeared to have disrupted levels of the hormone cortisol, known as the "stress hormone", in their body.
Dr Raquel Granell, who led the team which carried out the study, said that the findings, presented at Annual Congress of the European Respiratory Society (ERS) in Berlin, showed that "maternal stress in pregnancy was associated with paediatric asthma".
For the study, mothers-to-be were asked to rate how stressed they felt at 18 and 32 weeks of their pregnancy.
Their children were tested for asthma at seven-and-a-half years old and the results were compared.
Of those tested almost 13 per cent had asthma.
The risk of asthma was found to be 17 per cent higher among children whose mothers described themselves as stressed at 32 weeks and 14 per cent higher when they were stressed at 18 weeks, Dr Granell told the Congress, although the risk reached 65 per cent for extremely stressed women.
Dr Granell and her team believe that the results could underestimate the effects of anxiety on the immune systems of unborn children, as the study had lost touch with some of the most stressed women, making it more difficult to assess their risk.
• Music can help to relieve symptoms of stress, anxiety and depression in pregnant women, a new study shows.
Lullabies as well as natural sounds were the most popular stress-busting listening choices, scientists found.
Researchers from the College of Nursing at Kaohsiung Medical University, in Taiwan, played music to 116 pregnant women during their pregnancy.
Another group were given no listening material.
The results, published in the Journal of Clinical Nursing, show that women saw a fall of more than 10 per cent in their stress and depression levels, while listening to the music.
"The music group showed significant reductions in stress, anxiety and depression after just two weeks," said Professor Chung-Hey Chen, who led the study.
"In comparison, the control group showed a much smaller reduction in stress, while their anxiety and depression scores showed little or no improvement."
