5. Kennedy K, Rivera R, McNeilly A. Consensus statement on the use of breastfeeding as a family planning method. Contraception. 1988; 39(5):477–496.
6. Centers for Disease Control and Prevention. Update to CDC’s US Medical Eligibility Criteria for Contraceptive Use, 2010: Revised recommendations for the use of contraceptive methods during the postpartum period. MMWR. 2011;60(26):878–883.
7. Jackson E, Curtis K, Gaffield M. Risk of venous thromboembolism during the postpartum period: a systematic review. Obstet Gynecol. 2011;117(3):691–703.
8. Centers for Disease Control and Prevention. US Medical Eligibility Criteria for Contraceptive Use, 2010. MMWR. 2010;59(No. RR-4):1–86.
9. Kletzky OA, Marrs RP, Howard WF, McCormick W, Mishell DR Jr. Prolactin synthesis and release during pregnancy and puerperium. Am J Obstet Gynecol. 1980;136(4):545–550.
10. Labbok MH, Hight-Laukaran V, Peterson AE, Fletcher V, von Hertzen H, Van Look PF. Multicenter study of the Lactional Amenorrhea Method (LAM): I. Efficacy, duration, and implications for clinical application. Contraception. 1997;55(6):327–336.
11. Valdes V, Labbok MH, Pugin E, Perez A. The efficacy of the Lactational Amenorrhea Method (LAM) among working women. Contraception. 2000;62(5):217–219.