A recent report published in the Mayo Clinic Proceedings supports the hypothesis that women who smoke cigarettes before first full-term pregnancy have a 20 percent increased risk of breast cancer compared with women who begin smoking after the birth of their first child or never smoked.
This latest study is a strong indicator of the continued need for smoking-prevention messages to all, but especially ones tailored to this group of young women.
The levels of risk elevation are consistent with the risk levels reported from other epidemiological studies of cigarette smoking and breast-cancer risk, according to Janet Olson, Ph.D., a Mayo Clinic researcher and the lead author of the study.
The researchers did not find any evidence that the duration of smoking or number of cigarettes smoked per day affected risk of breast cancer among the smokers.
Scientists have known for many years that women who are young (under the age of 20) when they have their first baby are less likely to get breast cancer than women who are older (over the age of 35) at the birth of their first child.
It is not known exactly why this is true, but it is thought to be linked to the changes that take place in women's breasts and hormone levels during pregnancy.