There are many ways to reduce the arm circumference after delivery, including exercise, massage, dieting and so on. Here are some methods that may be useful:

-Exercise: You can reduce your arm circumference by exercising your arm muscles. For example, you can exercise with dumbbells or elastic belt.

-Massage: It can massage the arm and promote blood circulation, thus reducing edema and fat accumulation.

-Diet: You can reduce your body weight and fat intake by controlling your diet, thus reducing your arm circumference.