Iain is a distinctive boys' name in United States, ranking #1329 in 2001 with 98 recorded births. The name reached its all-time peak in 2003 with 126 births ranking #1181. Since 1996, the popularity has increased by 14.0%. In 2001, approximately 1 in every 19,825 boys born was named Iain. FALLING Recent data shows the name is currently falling.