The Lactational Amenorrhea Method (LAM)
Labbok MH, Hight-Laukaran V, Peterson AE, Fletcher V, von Hertzen H, Van Look PFA
Why it matters
LAM is often confused with breastfeeding generally. Real research shows that LAM is a defined method with specific conditions, and that fertility can return well before they are no longer met.
Limitations
LAM only applies when all of its criteria are met. Outside those criteria, breastfeeding is not a reliable form of pregnancy avoidance, and an individual's first ovulation can occur before the first postpartum period.
The Lactational Amenorrhea Method, usually shortened to LAM, is a structured way of using full breastfeeding to delay the return of fertility in the first months after childbirth. It is not the same as the general idea that breastfeeding lowers fertility. LAM has specific conditions, and it is only intended as a short-term option.
This multicenter study tested LAM as a defined method and supports the criteria that are still taught today: the parent has not had a return of menses, breastfeeding is full or nearly full, and the baby is under six months old.
What this research looked at
Researchers followed breastfeeding women in the first months after childbirth to see how often pregnancy occurred while the LAM criteria were met, and what happened when those criteria changed. The study contributed to the way LAM is taught and to the evidence base behind the well-known three criteria.
What the study found
When women were exclusively or nearly exclusively breastfeeding, had not yet had a return of menses, and were within six months of giving birth, pregnancy was uncommon. When any of those conditions changed, the protective effect could no longer be assumed. The study supported LAM as a temporary, defined method rather than a general statement about breastfeeding and fertility.
What this means in plain English
Breastfeeding alone is not a method of pregnancy avoidance. LAM, used carefully, is. The difference is in the rules. If a parent stops nursing as often, starts giving formula or solids, has any vaginal bleeding that looks like a return of menses, or moves past six months postpartum, LAM no longer applies and another approach is needed.
What this does not prove
The research does not show that breastfeeding always prevents pregnancy, that LAM continues to work past six months, or that fertility returns at the same time for every individual. Many people ovulate before their first postpartum period, which means it is possible to become pregnant during what looks like ongoing amenorrhea.
Important limitations
- All three LAM criteria must be met; missing any one means LAM no longer applies.
- Pumping, scheduled feeds, long stretches without nursing, and supplementation can change the hormonal picture.
- Some people ovulate well before six months, even when criteria appear to still be met.
- LAM is a bridge, not a long-term plan, and most users transition to another fertility awareness based method or another option afterward.
Why this matters for NFP education
LAM is one of the few formally studied options specifically for the early postpartum period. Teaching it accurately, criteria first, makes the difference between a useful tool and a misunderstanding that leads to an unintended pregnancy. It also opens an honest conversation about what to do next, since LAM is meant to be a temporary stage.
Related reading
- Lactational Amenorrhea Method (LAM), /glossary/lam
- Can I use NFP while breastfeeding, /questions/can-i-use-nfp-while-breastfeeding
- Postpartum, /glossary/postpartum
- Life stages, /life-stages
- How effective is NFP, /questions/how-effective-is-nfp
- Do I need a certified instructor, /questions/do-i-need-a-certified-instructor
Continue learning
Research summaries are easier to use when you also understand the basic biology, method differences, and how effectiveness claims are interpreted.
Original source
Contraception (1997) ↗