What is the cause of lactational amenorrhea (absence of menstruation during lactation)?

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From the Guidelines

Lactational amenorrhea can be used as a method of contraception if the woman is amenorrheic, fully or nearly fully breastfeeding, and less than 6 months postpartum, as outlined in the U.S. Medical Eligibility Criteria for Contraceptive Use, 2010 1. This method is based on the Bellagio Consensus, which provides the scientific basis for defining the conditions under which breastfeeding can be used safely and effectively for birth-spacing purposes. The main criteria for using lactational amenorrhea as a contraceptive method include:

  • Amenorrhea
  • Fully or nearly fully breastfeeding
  • Less than 6 months postpartum It is essential to note that lactational amenorrhea does not protect against sexually transmitted infections (STIs) and human immunodeficiency virus (HIV), and women at risk should be advised to use condoms or other contraceptive methods in addition to lactational amenorrhea. According to the guidelines, no medical conditions exist for which use of the lactational amenorrhea method for contraception is restricted, but women with conditions that make pregnancy an unacceptable risk should be advised that the lactational amenorrhea method might not be appropriate for them due to its relatively higher typical-use failure rates 1. When the conditions for lactational amenorrhea are met, it can provide effective contraception, but once any of these conditions changes, the woman should begin using another contraceptive method immediately as fertility may return.

From the Research

Definition and Effectiveness of Lactational Amenorrhea

  • Lactational amenorrhea is a method of contraception that utilizes breastfeeding to suppress ovulation and menstruation, providing a natural form of birth control 2.
  • The lactational amenorrhea method (LAM) is based on three simultaneous conditions: the baby is under 6 months, the mother is still amenorrheic, and she practices exclusive or quasi-exclusive breastfeeding on demand, day and night 2.
  • Studies have shown that LAM is at least 98% effective in preventing pregnancy, comparing favorably with other contraceptive methods 2, 3.
  • The effectiveness of LAM is attributed to the reduction in gonadotropin-releasing hormone, luteinizing hormone, and follicle-stimulating hormone release, resulting in amenorrhea, through an intracerebral opioid pathway 2.

Understanding and Utilization of Lactational Amenorrhea

  • Despite its effectiveness, LAM may be underutilized due to incomplete perinatal counseling, with many women unaware of its benefits and how to use it correctly 4.
  • A study found that only 8% of pregnant women believed exclusive breastfeeding reduces the chance of pregnancy "a lot" within 6 months of delivery, and only 2% indicated that exclusive breastfeeding is typically more effective than birth control pills or condoms 4.
  • Women who planned to use LAM were more likely to know that breastfeeding delays return of menses and provides protection from pregnancy until menses return, highlighting the importance of education and counseling on LAM 4.

Comparison with Other Contraceptive Methods

  • LAM has been compared to other contraceptive methods, including condoms and birth control pills, with studies showing that it is a highly effective and efficient tool for individual women to utilize physiology to space births 2, 3.
  • The probability of pregnancy during lactational amenorrhea is similar to that of other modern contraceptive methods, making it a viable option for women who are breastfeeding and wish to delay pregnancy 3.
  • LAM avoids double protection, saves resources, and is especially suitable for couples interested in natural family planning, with acceptance from religious authorities 2.

Counseling and Support for Lactational Amenorrhea

  • Counseling about good breastfeeding and weaning practices is essential to maintain amenorrhea and fertility suppression, with healthcare providers playing a crucial role in promoting LAM and providing support to women who choose to use it 2, 3.
  • A "Breastfeeding-LAM-Family Planning" team can be helpful in maternity wards for promoting modern breastfeeding, LAM, and contraception, and for alleviating barriers and misconceptions 2.
  • Introduction of LAM in family planning programs demands training, attention to working mothers, positive attitudes of health personnel, and close links between postpartum and family planning teams 2.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Postpartum contraception: the lactational amenorrhea method.

The European journal of contraception & reproductive health care : the official journal of the European Society of Contraception, 1997

Research

Contraceptive efficacy of lactational amenorrhoea.

Lancet (London, England), 1992

Research

Understanding of Lactational Amenorrhea As a Contraceptive Method Among U.S. Pregnant Women.

Breastfeeding medicine : the official journal of the Academy of Breastfeeding Medicine, 2023

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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