STRESSED mothers-to-be could be condemning their children to a life of asthma and allergies, new research has found.

Scientists believe a mother's stress during pregnancy over issues like finances and relationships can affect a baby's immune system development, making them more sensitive to asthma and allergy triggers.

Hughesdale toddler Ella has just been diagnosed with asthma, joining about 2.2 million Australians with the condition.

Mum Julie Brodribb admits feeling frazzled at times during pregnancy but believes Ella, 2, is more likely to have inherited her asthma.

"I don't think I was any more stressed than the average first-time mum," she said.

"I did worry about little things. But I have been a severe asthmatic since I was eight months old, so I think Ella has me to thank for hers."

Asthma Foundation of Victoria chief executive Robin Ould said genetics and environmental influences caused asthma and allergies.

"The key environmental factor is exposure to triggers, and stress can also play a part in that," he said.

Researchers from the Harvard Medical School in the US found higher levels of an antibody indicating immune response in the cord blood of infants whose mothers were stressed during pregnancy.

Dr Rosalind Wright said: "This further supports the notion that stress can be 'breathed' into the body and influence the body's immune response similar to physical pollutants like allergens."