Objective: To determine the efficacy of the lactational amenorrhea method of family planning (amenorrhea during full or nearly full breastfeeding for 6 months postpartum).
Design: Prospective noncomparative study.
Setting: Normal breastfeeding women in Karachi and Multan, Pakistan, most delivered at home by a midwife.
Patients: Three hundred ninety-nine newly delivered mothers who successfully had breastfed a previous child and chose the lactational amenorrhea method to prevent a subsequent pregnancy, 391 of whom were followed for a full year.
Interventions: Mothers were taught, before or shortly after delivery, to use the method and were interviewed in their homes each month by a Lady Health Visitor.
Main outcome measure: Life-table pregnancy rates. Periods of postpartum or lactational abstinence were excluded in the calculation of the pregnancy rates.
Results: During full or nearly full breastfeeding, while the women were amenorrheic and not otherwise contracepting, the rate of pregnancy was 0.6%. The pregnancy rate during lactational amenorrhea alone was 1.1% at 1 year postpartum.
Conclusion: The lactational amenorrhea method was found to be highly effective for 6 months. A high degree of contraceptive protection endures for a full year during lactational amenorrhea, but not after the return of menses during breastfeeding.
PIP: 399 mother-infant pairs were admitted into the study, 99 in the rural areas around Multan and 300 in Karachi. 378 remained in the follow-up for the full year. The mean age of the volunteers was 27.2. 25% were from the rural areas, and 37.6% were able to read and write. The women reported an average of 4.4 pregnancies and had 3.9 living children. Only 6% ever had used a family planning method in the past, and this included withdrawal as well as modern contraceptive methods. 26.4% of the women returned to menses during the first 6 months postpartum, and 40.7% of the infants were given regular supplements by this time. Considering both factors together, 47.9% of women were still protected by the lactational amenorrhea method (LAM) by the end of the 6th month postpartum. By the end of the 8th month, virtually all infants were receiving regular supplements, although only 7.4% had been weaned by the end of follow-up at 1 year postpartum. By the end of 12 months there were 29 pregnancies, including two miscarriages. Of the two pregnancies that occurred during amenorrhea, one occurred after 5 months postpartum (single LAM failure) and the other occurred at 9 months postpartum, 3.5 months after regular supplementation began. The single LAM failure, which occurred during the 6th postpartum month, resulted in a life-table pregnancy rate of 0.58% (95% confidence interval [CI], 0.00-1.58%). The rate of pregnancy during the first 6 months postpartum during breastfeeding in the absence of the use of another contraceptive constituted the failure rate of the LAM during correct plus incorrect use. During use of the LAM so defined, 0.96% were pregnant by the end of 5 months postpartum (95% CI, 0.00-2.15%) and 1.65% were pregnant by 6 months (95% CI, 0.12-3.18%). Two pregnancies occurred by the end of a year, for a 12-month life-table pregnancy rate of 1.12% (95% CI, 0.00-2.59%).