Efficacy and duration of LAM are enhanced with more intense breastfeeding patterns, especially during the earlier weeks and months. Less than six months postpartum . The effectiveness of LAM has been demonstrated in clinical trials and in programmatic use. If any one of the criteria is unmet, the use of another method which is appropriate for use during breastfeeding should be recommended for continued high pregnancy protection. The method allows deviation from the three criteria without a sudden increase in risk of unplanned pregnancy.
Menses return is the least flexible.
If a woman has deviated only slightly from the fully or nearly fully breastfeeding criterion, she should be re-counseled about appropriate breastfeeding and may use LAM thereafter if she returns to nearly fully breastfeeding. Small amounts of other food or liquid which do not replace breastfeeds do not have a substantial effect on the woman's fertility. However, lowered frequencies of breastfeeding and regular supplementation to the infant's diet are associated with an increased risk of menses return and a higher probability that ovulation will precede that menses. Milk expression by hand or pump may produce sufficient breast stimulation to prevent ovulatory activity. LAM can be taught during the prenatal, perinatal, or postnatal periods.