The longest baby girls with the largest heads are three times as likely to develop breast cancer many decades later, European researchers reported in the British Medical Journal.

Based on information from more than 5,000 women born at the Uppsala Academic Hospital in Sweden between 1915 and 1929, the researchers found that the risk of breast cancer before menopause was most strongly linked to head size and length at birth.

The researchers also discovered that women who weighed at least 8.8 pounds at birth were 3.5 times as likely to get breast cancer before menopause as women who weighed less 6.6 pounds at birth.

However, breast cancer before menopause is a relatively rare form of the disease, and the researchers reported that their analysis showed that "birth size was not associated with rates of breast cancer in postmenopausal women."

Based on their findings, the researchers speculated that levels of growth hormones in the womb -- which could affect the fetal growth rate and result in larger head size and greater length at birth -- might be the relevant factor in premenopausal breast cancer years later.

Other sources: British Medical Journal