Breastfeeding is one of the natural ways of contraception. During the initial few months after the birth of a child, exclusive breastfeeding does increase levels of various hormones and hence ovulation does not occur. Prolactin is responsible for the delay of periods in women. Estrogen, progesterone, LH, FSH etc are few hormones whose levels are altered following childbirth. However, once the frequency of breastfeeding reduces, the menstrual cycle returns to normal.
There have been definite reports about pregnancy even during the so-called lactation amenorrhoea. This is usually missed and at a later date, a couple may land up with unwanted pregnancy. Doctors do recommend using alternate form of contraceptives like a condom or a copper-T during this period. If pregnancy is suspected, an early visit to the gynaecologist is advised. Also, one will be asked if one wants to continue with the pregnancy.