Many others? Isabella the Catholic? I only know of one stillbirth (a son) in 1475, a daughter who died shortly after birth (Maria's twin sister) and SOME mention a miscarriage/stillborn son in 1483. All in all, that's 2/3 dead children, versus 5 surviving ones in 10 years ('75-'85), a slightly better record than her English married daughter at around the same age (24yo vs. 29yo)
Apparently there was a few between Isabella in 1470 and Juan in 1498. A stillborn son in 1475 and a few others are sometimes mentioned. And even if there was only 3, that's still a lot. Not the terrible amount of Catherine of Aragon or Catherine of Portugal, but still a lot.