If, for example, a 25-year-old woman who is a size 12 goes up a size every 10 years until after she goes through the menopause, she could be increasing her chances of getting the disease.
Going up two skirt sizes in this same period would also be very harmful, with a 77% greater risk of developing breast cancer.
The study, published in the journal BMJ Open, examined the self-reported "central obesity" of more than 90,000 women across England aged 50 and over who had no known history of breast cancer.
They were asked about their skirt size when they were aged 25, their current size and a number of other health questions.
During the three-year follow-up period 1,090 women developed the disease.
The researchers found that a unit increase in UK skirt size every 10 years between 25 and postmenopausal age was linked to a 33% increased risk of breast cancer.
Going up two skirt sizes in the same period was associated with a 77% greater risk, they added.
They also found that a reduction in skirt size decreased the risk of breast cancer but cautioned that three quarters of the women surveyed increased their skirt size during their adult lives.
"These findings may provide women with a simple and easy to understand message given that skirt size has been found to be a reliable measure for changes in waist circumference and one that women may relate and understand better in comparison to other measures such as BMI (body mass index)," said the researchers from London and Manchester.
"Between 20s and postmenopausal age, an increase in skirt size by one unit every decade increases the risk of postmenopausal breast cancer by 33%."
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Commenting on the study, Simon Vincent, assistant director of research at charity Breakthrough Breast Cancer, said: "We know that 40% of breast cancers could be prevented by changes to lifestyle such as being regularly active and maintaining a healthy weight.
This study highlights an easy way to monitor your weight gain over time. Women are more likely to remember their skirt size when they were younger than their BMI.
"Here at Breakthrough Breast Cancer, we encourage all women to raise their pulse and reduce their risk. Women should take part in regular physical activity of moderate intensity for 3.5 hours per week."