Breastfeeding and Fertility Eligibility Checker
Check if breastfeeding can work as contraception (LAM). Free, private and instant.
How to use the Breastfeeding Fertility
- Enter baby’s age (months).
- Choose how is your baby fed?: Only breast milk, whenever baby wants (no formula or solids), Almost entirely breast milk, with occasional formula or water, Regular formula or solid food as well or Mostly expressed or pumped milk.
- Choose longest gap between feeds: Up to 4 hours in the day and 6 hours at night or Longer than that.
- Choose have your periods returned?: No bleeding since the first 8 weeks after birth, Only bleeding in the first 8 weeks (normal after birth) or Yes, a period or regular bleeding has returned.
- Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.
About the Breastfeeding Fertility
Breastfeeding can delay ovulation, but only if specific conditions are met. This checker tests the three LAM criteria: baby under 6 months, full or near-full breastfeeding day and night, and no return of periods.
Also known as: LAM calculator, lactational amenorrhea method, breastfeeding birth control, can I get pregnant while breastfeeding.
Worked example
- Baby’s age: 3 months
- How is your baby fed?: Only breast milk, whenever baby wants (no formula or solids)
- Longest gap between feeds: Up to 4 hours in the day and 6 hours at night
- Have your periods returned?: No bleeding since the first 8 weeks after birth
Lactational amenorrhea method (LAM): May work (3 of 3 criteria met). You meet all three LAM criteria, so breastfeeding can act as a temporary method that is about 98% effective, but only for up to 6 months after birth and only while all three stay true.
- Baby under 6 months: Yes
- Full or near-full breastfeeding: Yes
- No period returned: Yes
- Fertility may return: Not before 6 months
Formula and cut-offs
LAM works (about 98%) only if all three apply: baby is under 6 months old, you are fully or almost fully breastfeeding (day gaps up to 4 hours, night up to 6 hours), and your periods have not returned.
Frequently asked questions
Can I get pregnant while breastfeeding?
Yes. You can ovulate before your first period returns, so you can conceive while breastfeeding.
How well does breastfeeding work as contraception?
About 98% effective for the first 6 months if all LAM criteria are met, and much less after that.
Which contraception is safe while breastfeeding?
Condoms, progestin-only methods, implants, IUDs and injections are generally compatible. Ask about timing for oestrogen pills.
Sources and references
- World Health Organization - Family planning/contraception methods
- NHS - Contraception guide
- CDC - Sexually transmitted infections (STIs)
Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.
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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.