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Interpregnancy Interval Calculator (How Long to Wait Between Pregnancies)

Q: How long should I wait to get pregnant again after giving birth?

The WHO recommends at least 24 months between a live birth and the next conception. ACOG advises avoiding a new pregnancy within 6 months and explains that intervals under 18 months carry some extra risk. Talk to your doctor about your age, health and previous birth.

Q: How long should I wait after a miscarriage?

The WHO suggests waiting at least 6 months after a miscarriage or abortion. More recent studies show no clear harm from conceiving sooner once you feel physically and emotionally ready, so many doctors only advise waiting for one normal period.

Q: What risks come with a short interval?

Short intervals are linked to preterm birth, low birth weight, small-for-gestational-age babies, maternal anemia and, after a cesarean, a higher risk of uterine rupture during a trial of labor.

Q: Is the interpregnancy interval the same as the birth spacing?

No. The interpregnancy interval goes from the end of one pregnancy to the next conception; the birth-to-birth interval is about 9 months longer because it includes the next pregnancy.

Calculate the time between your last birth or pregnancy loss and your next planned conception, and compare it with the WHO and ACOG recommendations on pregnancy spacing.

Date of your last birth or pregnancy loss

How that pregnancy ended

Planned conception date

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How it works

Interpregnancy interval (months) = (conception date − date of last birth or loss) ÷ 30.44 · WHO: wait ≥ 24 months after a live birth, ≥ 6 months after a miscarriage or abortion · ACOG: avoid < 6 months; < 18 months carries some extra risk

The interpregnancy interval runs from the end of one pregnancy to the conception of the next. A WHO technical consultation (2005) recommends waiting at least 24 months after a live birth and at least 6 months after a miscarriage or induced abortion before trying again, to lower the risk of adverse maternal, perinatal and infant outcomes. ACOG and SMFM (Obstetric Care Consensus 8, 2019) advise avoiding intervals shorter than 6 months and counseling about the modestly higher risks of intervals under 18 months, such as preterm birth and low birth weight. The due date shown assumes a pregnancy of 266 days from conception.

Worked example

Your last baby was born on June 1, 2025 and you plan to conceive on October 8, 2026: the interval is 494 days ÷ 30.44 = 16.2 months. That is a short interval (under 18 months); the WHO recommends waiting until June 1, 2027, about 7.8 months longer. Conceiving on October 8, 2026 would give a due date of July 1, 2027, a birth-to-birth interval of 25.0 months.

Sources: WHO (2007) Report of a WHO technical consultation on birth spacing · ACOG/SMFM Obstetric Care Consensus No. 8: Interpregnancy care (2019)

Frequently asked questions

How long should I wait to get pregnant again after giving birth?

The WHO recommends at least 24 months between a live birth and the next conception. ACOG advises avoiding a new pregnancy within 6 months and explains that intervals under 18 months carry some extra risk. Talk to your doctor about your age, health and previous birth.

How long should I wait after a miscarriage?

The WHO suggests waiting at least 6 months after a miscarriage or abortion. More recent studies show no clear harm from conceiving sooner once you feel physically and emotionally ready, so many doctors only advise waiting for one normal period.

What risks come with a short interval?

Short intervals are linked to preterm birth, low birth weight, small-for-gestational-age babies, maternal anemia and, after a cesarean, a higher risk of uterine rupture during a trial of labor.

Is the interpregnancy interval the same as the birth spacing?

No. The interpregnancy interval goes from the end of one pregnancy to the next conception; the birth-to-birth interval is about 9 months longer because it includes the next pregnancy.

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This calculator is for education only and does not replace your midwife, obstetrician or doctor. Contact your care team straight away about bleeding, fluid leaking, reduced baby movements, severe pain, fever or anything that worries you.