During pregnancy, high levels of estrogen and progesterone, plus prolactin, block the production of luteinizing hormone (LH) and follicle stimulating hormone (FSH), preventing ovulation. After birth, estrogen and progesterone levels drop but prolactin remains high enough to block ovulation if breastfeeding occurs frequently.
Breastfeeding is the natural sequel to pregnancy. Weight gain during pregnancy,for example, is largely to support breastfeeding in the postpartum period. Breastfeeding is also the most significant spacer of pregnancies worldwide.
The return of fertility after giving birth is related to the frequency of breastfeeding. Each feed stimulates the production of prolactin, which prevents ovulation.
Postpartum women can be divided into the following categories.
Mothers who never begin to breastfeed, or who stop breastfeeding in the early days after a baby’s birth, must assume a rapid return of fertility, and must begin keeping an NFP chart at 21 days postpartum. The earliest documented return of ovulation is Day 27 postpartum.
Partial Breastfeeders/Mixed Feeding
The mother who gives supplementary bottle feeds cannot rely on steady production of prolactin, and so must be prepared for the return of fertility. She too must keep a chart from Day 21 onwards.
Exclusive Breastfeeders and LAM1,2
The Lactation Amenorrhea Method (LAM) of natural family planning was developed for exclusive breastfeeders. A mother who meets the following criteria can consider herself infertile until six months postpartum.
- The baby is less than six months old.
- The baby is exclusively breastfed and feeds at least every four hours by day and every six hours by night.
- The mother has not experienced any vaginal bleeding after 56 days postpartum.
Women who meet the LAM criteria should begin charting at five months in preparation for the six month deadline for LAM. Note that many women who continue breastfeeding longer than six months may not have a return of fertility for some months.
Once any condition of LAM is no longer met (e.g. baby receives supplements other than breastmilk, or sleeps all night) the woman must begin to chart.
Breastfeeders outside LAM criteria
Women who fall just outside of LAM, e.g. exclusive breastfeeders whose babies sleep longer at night, can begin charting at five weeks postpartum.
Special rules apply in the postpartum situation, and the client should be taught by a qualified NFP teacher. To be most effective, the woman must be taught the ‘symptothermal double-check’ method of Natural Family Planning by a qualified natural family planning teacher.
- Perez, A. Labbok, MH. Queenan JT. ‘Clinical study of the Lactational Amenorrhoea Method for family planning'; Lancet 1992; 339; 968-70B
- Kennedy KI, Rivewra, R. McNeilly AS.; ‘Consensus Statement on the use of breastfeeding as a family planning method'; Contraception, 1989; 39 (5): 477-496
To be most effective, the woman must be taught the symptothermal double-check method of Natural Family Planning by a qualified natural family planning teacher.