Amenorrea de la lactancia para la planificación familiar

BACKGROUND: Fifty percent of pregnancies are unwanted. For several reasons, eg difficulty in obtaining contraceptives, no or ineffective contraception is used to prevent these pregnancies. The lactational amenorrhea method (LAM) is a contraceptive method where the mother is informed and supported how to use breastfeeding, also for contraception. LAM is available and accessible to many women. OBJECTIVES: To assess the effectiveness of LAM as a contraceptive method in fully breastfeeding women, who remain amenorrheic. We compared the effectiveness of LAM, as defined in the 1988 Bellagio Consensus statement, with alternative definitions of LAM using pregnancy and menstruation life tables. SEARCH METHODS: MEDLINE 1966 to 2008; EMBASE 1988 to 2008; reference lists of studies; review articles; books related to LAM; published abstracts from breastfeeding, reproductive health conferences; e-mails with study coordinators. SELECTION CRITERIA: Out of 459 potentially relevant studies, 159 investigated the risk of pregnancy during LAM or lactational amenorrhea. Inclusion criteria: prospective study, cases (intervention group) and, if available, controls, had to be sexually active; pregnancy had to be confirmed by physical examination or a pregnancy test. Our endpoints were life table menstruation rates and life table pregnancy rates. We included 14 studies reporting on 10 intervention groups and two control groups that met the inclusion criteria. We identified one additional study in the 2007 update. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data; disagreements were resolved through discussion. We analyzed the studies using narrative methods because of their heterogeneity. MAIN RESULTS: For the primary outcome, two controlled studies of LAM users reported life table pregnancy rates at 6 months of 0.45 and 2.45 percent and six uncontrolled studies of LAM users reported 0-7.5 percent. Life table pregnancy rates for fully breastfeeding women who were amenorrheic but not using any contraceptive method were 0.88 percent in one study and 0.9 to 1.2 percent (95% confidence interval 0.0 to 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 and 39.4 percent. AUTHORS' CONCLUSIONS: We found no clear differences in life table pregnancy rates between women using LAM and being supported in doing so, and fully breastfeeding amenorrheic women not using any method. Because the length of lactation amenorrhea in women using LAM was very different between the populations studied, and is population specific, it is uncertain whether the LAM extends lactational amenorrhea.