Breastfeeding is beneficial for mother and baby. It provides the baby with a complete form of nutrition and immunological defence against infectious diseases. Breastfeeding strengthens the attachment between mother and baby. Breast feeding also acts as a natural contraceptive. 

Lactational Amenorrhoea Method (LAM)

The hormone prolactin, which is produced towards the end of pregnancy, stimulates the the production of breast milk. It also has a suppressant effect on the ovaries blocking ovulation. Each time the baby suckles at the breast he or she stimulates the secretion of prolactin. The level falls again after 3-4 hours. Provided the baby suckles frequently the prolactin level remains high, the milk supply is maintained and ovulation is suppressed.

In 1998 a group of world experts agreed the necessary criteria for breastfeeding to act as a contraceptive. They termed the method lactational amenorrhoea method (LAM) and issued a consensus statement concluding that:

There is only 2% risk of pregnancy when:

  • The baby is less than 6 months old
  • The mother is exclusively (or almost exclusively) breastfeeding day and night, and
  • her periods have not returned

If any of the these conditions change, the risk of pregnancy is increased and the woman cannot rely on breastfeeding alone.

CAUTION: Bleeding is a warning sign of fertility, but some women will ovulate before their first period, so it is possible to go straight from one pregnancy to another without having a period.

Factors which may increase the risk of pregnancy

Women using LAM should understand the factors which may precipitate the return of fertility thus increasing the risk of pregnancy. These include:

  • less frequent suckling (longer intervals between feeds, particularly at night)
  • a reduction in total suckling time over 24 hours
  • the baby sleeping through the night
  • the introduction of supplementary feeds (formula, juice and solids)
  • the use of a dummy as a comforter
  • expressing milk (separation from the baby or returning to work)
  • anxiety, stress or illness in the mother or baby
  • the age of the baby (fertility returns over time despite breastfeeding)

When the LAM criteria no longer apply, the mother should continue to breastfeed her baby but must switch to another family planning method. For further information on LAM and returning fertility see The Complete Guide to Fertility Awareness 

Women who wish to rely on the natural contraceptive effect of breastfeeding should get help from an experienced practitioner.  A FAM practitioner will be able to advise on the transition from LAM to FAMs.