Weight gain of 25-35pounds (11-16 kg) is a healthy sign in pregnancy. But gaining extra weight is not a good sign.
The Lombardi Cancer Center in Washington state that if a woman gains more than 50pounds (22.5 kg) and does not lose this excess weight after delivery, it triples her risk of developing breast cancer post menopause.
The researchers at the Lombardi Cancer Center claim that every extra 2.2pound (1 kg) increases the risk of breast cancer by 3.9%.
The American association for cancer research has reported that women who gain excessive weight during pregnancy and do not lose it later have an increased risk of developing breast cancer after menopause.
Pregnancy increases the estrogen levels in the blood. This elevated level of estrogen is associated with an increased risk breast cancer.
Excessive weight gain in pregnancy has been linked to high circulating estrogen levels. During pregnancy the breast undergoes many changes to prepare for lactation. Due to the higher levels of estrogen there is marked proliferation (cell division) in the breast cells. The normal breast cells differentiate to form milk secreting alveoli and if tumor cells are present they continue to multiply and gradually form a detectable tumor.
Therefore weight gain in pregnancy should be limited to 25-25 pounds (11-16 kg). Women should exercise post delivery and shed the extra pounds gained during pregnancy to lower the risk of breast cancer.