If you mean worldwide abortion numbers since 1975, the most widely cited estimates come from organizations like the Guttmacher Institute and the World Health Organization (WHO), which compile global reproductive health data from national health ministries, demographic surveys, and peer-reviewed studies.

Here’s the breakdown:

🔹 Estimated global number since 1975

• Researchers estimate ~1.6 to 1.7 billion abortions worldwide between 1975 and today.

• This is based on an average of ~50–73 million abortions per year (the range depends on the data source and reporting accuracy).

🔹 How they estimate the numbers

1. Official reports — Some countries have mandatory reporting of abortions from hospitals and clinics (e.g., much of Europe, Canada, parts of Asia).

2. Household & demographic surveys — In countries where abortion is restricted or underreported, health surveys ask women about reproductive history, sometimes indirectly.

3. Statistical modeling — For places with poor or no reporting, researchers estimate based on:

• Birth rates

• Contraceptive prevalence

• Rates of unintended pregnancies

• Ratios from similar countries with reliable data

4. Adjustments for underreporting — Even in countries with legal abortion, private clinics or informal providers might not report every case, so researchers use correction factors.

Because of the large margins of uncertainty, these numbers are approximate — not exact counts. The WHO and Guttmacher emphasize that they’re best estimates rather than precise tallies.