Twin Birth Data Atlas — derived HMBD dataset
Generated: 2026-07-10
Source version: 2025-05-26
Source: https://www.twinbirths.org/en/data-metadata/
License: CC BY 4.0 — https://creativecommons.org/licenses/by/4.0/

Recommended attribution:
Human Multiple Births Database (2025). Institut national d'études démographiques - INED (distributor). Retrieved from https://www.twinbirths.org on 10 July 2026. Derived selection and presentation by TwinCalc.

Metric: twin deliveries per 1,000 total deliveries. Do not compare this directly with the CDC twin birth rate, which counts twin children per 1,000 total births. Country years and stillbirth definitions differ.

Selection rule: For duplicate country-years, prefer rows including stillbirths (code 1), then excluding stillbirths (0), mixed (2), unknown (99); break ties using the largest total-delivery denominator.