Stretch marks are ugly streaks that appear on the skin. They are caused by excessive physical stretching of the skin caused by Pregnancy, Weight gain, Medications and some diseases such as cushing's syndrome. The skin stretches so quickly that the collagen and elastic tissue are damaged, leading to the characteristic line-like appearance of the skin.

Causes of Stretch Marks:

• Pregnancy. Most pregnant women develop stretch marks by the end of their pregnancy. The physical stretching of the skin, along with hormonal factors, likely play a role.
• Weight gain. Stretch marks sometimes occur during substantial weight gain. Weightlifters also can develop stretch marks, particularly on the arms. Adolescents may notice stretch marks during growth spurts.
• Medication use. Corticosteroid creams, lotions and pills and chronic steroid use can cause stretch marks.
• Conditions or diseases. Cushing's syndrome and adrenal gland diseases can cause widespread stretch marks as can Marfan syndrome, Ehlers-Danlos syndrome and other hereditary (genetic) disorders.

Stretch marks are commonly found in abdomen, breasts, upper arms, buttocks and thighs.

Stretch marks are more common in women — especially pregnant women — than in men. Most pregnant women experience stretch marks by the end of their third trimester.

Other risk factors include:
• Younger women
• Women with larger babies
• Overweight or obese women
• Corticosteroid medication use