Pregnancy Spacing Calculator: Three Rules, One Date

There is no single number here, and any calculator that pretends otherwise is hiding something. The tool below applies the WHO thresholds — 24 months after a birth, 6 months after a loss — to your date. Two other bodies publish different figures, and the gap between them is the most useful thing on this page.

Three organizations, three different numbers

Source	What it says about spacing after a live birth
World Health Organization (2007)	Wait at least 24 months before attempting the next pregnancy
ACOG, Optimizing Postpartum Care	Optimal interval 18 months to 5 years; advise avoiding intervals under 6 months
Office on Women’s Health (HHS)	Space pregnancies at least 12 months apart

These are not versions of one recommendation. The WHO figure came out of a 2007 consultation built largely on observational studies from outside the United States. The ACOG position, quoted here as the two US systematic reviews transcribe it, gives a range rather than a floor. The Office on Women’s Health, writing for the public, uses 12 months and adds that becoming pregnant again within a year of giving birth raises the chance the next baby arrives too soon.

Where they agree is at the bottom end: every one of them treats an interval under six months as the one to avoid.

What the US evidence actually shows

A 2019 systematic review restricted to high-resource settings found intervals under 6 months associated with increased risk of preterm birth, small-for-gestational-age birth and infant death — but described the results as inconsistent, and noted plainly that there are no federal recommendations on healthy birth spacing for the United States.

The expert work group convened by the HHS Office of Population Affairs reached the same uncomfortable place: the association is real in the data, the studies rarely control for the things that would explain it, and reverse causation is hard to rule out. A pregnancy that ended early leaves a shorter interval behind it, which makes short intervals look worse than they may be. The detailed version is in risks of pregnancies too close together.

The interval is measured to conception, not to the next birth

This trips people up constantly. The interpregnancy interval starts at the birth and ends at the next conception. Add roughly nine months of pregnancy and a 24-month interpregnancy interval puts about 33 months between the two children.

It also means the clock is running before you notice. Ovulation can return within weeks, and it returns before the first postpartum period, so the interval can start closing without a single visible sign — see when fertility returns after birth and the postpartum fertile window calculator.

When the date on this page is not your date

Age is the obvious one. Somebody at 39 weighing a 24-month wait is trading one risk for another, and no calculator prices that trade. A prior cesarean adds a separate question about the uterine scar, covered in how long after a C-section you can get pregnant. After a pregnancy loss the American evidence points the other way entirely, which is why how soon you can conceive after a miscarriage gets its own page.

This content is informational and does not replace prenatal or preconception care. The interval that fits you is a conversation with a clinician who knows your history.