Breastfeeding still accounts for a significant proportion of all fertility reduction, the average birth interval being longer among populations that breastfeed. However, per se it is not reliable for individual fertility suppression. The lactational amenorrhea method (LAM) is a highly efficient tool for the individual woman to utilize physiology to space births. Suckling induces a reduction in gonadotropin releasing hormone, luteinizing hormone and follicle stimulating hormone release, resulting in amenorrhea, through an intracerebral opioid pathway: beta-endorphins inhibit gonadotropin releasing hormone and dopamine secretions, which, in turn stimulates prolactin secretion and milk production. Reduced suckling precipitates the return of ovulation. During lactation, menses before 6 months are mostly anovulatory, and fertility remains low. The lactational amenorrhea method is based on three simultaneous conditions: (1) the baby is under 6 months; (2) the mother is still amenorrheic; and (3) she practises exclusive or quasi-exclusive breastfeeding on demand, day and night. Experiments with LAM extended to 9-12 months are ongoing. We use a standardized algorithm to present LAM. The lactational amenorrhea method is a way both to space births and to support breastfeeding, which should be replaced by a contraceptive method in due course. A 'Breastfeeding-LAM-Family Planning' team is very helpful in maternity wards for promoting modern breastfeeding, LAM, and contraception, and for alleviating barriers and misconceptions. The lactational amenorrhea method is at least 98% effective, comparing favorably with other contraceptive methods. Acceptability and continuity are not very well known; as with other 'natural' methods the figures are probably low in a general population but high for motivated couples. The lactational amenorrhea method avoids double protection, and thus saves resources, is especially (but not exclusively) suitable for couples interested in natural family planning and is accepted by religious authorities. The lactational amenorrhea method gives time to decide upon a long-term method of contraception. Unwanted pregnancies, although infrequent, conceived while using LAM result in very short, high-risk birth intervals. Introduction of LAM in family planning programs demands training, attention to be given to working mothers, positive attitudes of health personnel, close links between postpartum and family planning teams, situation analysis, budgets, evaluations, follow-up activities, modifications of record keeping systems and computing programs, and of national family planning guidelines. In conclusion, LAM is an efficient family planning method which should be promoted. The lactational amenorrhea method should always include the shift to another method when its criteria are no longer implemented.