A Cochrane review (abstract [Abstract], review [Abstract]) included 9 intervention groups and 2 control groups in observational studies. Lactational amenorrhea method (LAM) is defined as a method during the first 6 months postpartum in amenorrheic women who are fully or nearly fully breastfeeding. For the outcome two controlled studies of LAM users reported life table pregnancy rates at 6 months of 0.45 and 2.45 percent, one controlled study reported 5% pregnancies in the absence of life table rates per month, and 8 uncontrolled studies of LAM users reported 0-7.5 percent. Life table pregnancy rates of women fully breastfeeding and amenorrheic but not using any contraceptive method were 0.88 in one study and 0.9-1.2 percent (95% CI 0. 0-2.4 ) in a second study, depending on the definition of menstruation used. The life table menstruation rate at 6 months in all studies varied between 11.1-39.4 percent.
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