How it is calculated
- Not breastfeeding: ovulation can return as early as 3–4 weeks, on average 6–12 weeks, and may happen before the first period.
- Exclusive breastfeeding (day and night, no supplements) with no periods: high protection (lactational amenorrhoea method, LAM) for up to 6 months only.
- Partial breastfeeding: fertility often returns sooner and unpredictably.
- Spacing: the WHO recommends at least 24 months between birth and the next pregnancy for mother and baby’s health.
Worked example
Birth on 1 March 2026 with exclusive breastfeeding: estimated LAM protection ends 1 September 2026, and the recommended next pregnancy is from 1 March 2028.
Frequently asked questions
Can I get pregnant before my period returns?
Yes — ovulation comes about two weeks before the first period, so pregnancy can happen without seeing one.
Is breastfeeding reliable contraception?
Only when all three conditions hold: exclusive breastfeeding, no periods, and baby under 6 months.
What about after a caesarean?
Many doctors advise waiting at least 18 months to reduce uterine risks in the next pregnancy.