Hi, Duphaston contains the hormone dydrogesterone which is an analogue of the natural hormone synthesized in the body called Progesterone. Progesterone is the hormone that helps to sustain the pregnancy. It starts from development of uterine endometrium to sustaining the pregnancy. It helps in the development of uterine endometrium where the fertilized egg will get implanted. If the egg is not fertilized, the progesterone level falls, thereby shedding of uterine endometrium with its blood supply which is called as Menstruation. Duphaston contains hormonal analogue of Progesterone can be taken during breastfeeding. It is passed to the child through breastmilk in small amount. But, it does not produce any adverse effect in the child. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Pradeepraj, General & Family Physician