A new study suggests that pregnancy does not increase the risk of dying for women diagnosed with breast cancer.
The study by Toronto researchers found that five-year survival rates were similar for women who were pregnant around the time of a breast cancer diagnosis and those who were not pregnant.
Some doctors recommend that women wait two years before becoming pregnant after they finish treatment for breast cancer.
The new research suggests those women need not delay their pregnancy.
Principal researcher Dr. Steven Narod of Women's College Hospital says it appears pregnancy at the time of breast cancer does not appear to pose a risk to the mother.
The study, published Thursday in the journal JAMA Oncology, analyzed health records for more than 7,500 breast cancer patients aged 20 to 44 in Ontario between 2003 and 2014. Overall survival was 88 per cent for women with no pregnancy, 82 per cent for those with breast cancer while pregnant, and about 97 per cent for women who got pregnant six months or more after a breast cancer diagnosis.
The researchers found that early age at diagnosis was associated with more aggressive breast cancers, but it was not the pregnancy that was the risk factor.
"We know that breast cancers in young women are more aggressive and have a higher risk of recurring," said Narod.
"Our work shows that we need more studies to understand why younger women fare worse, and how to help them recover from breast cancer."