Ay nako, that's such a common worry! Honestly, if baby's been head down since 2nd trimester, mas mataas ang chances na manatili siya nyan, babies don't usually flip around randomly na ganyan, especially kung comfortable na siya sa position haha. Best thing talaga is to mention it to your OB sa next check-up so they can confirm baby's position at mag-ease your mind, pero I'm betting your little one is gonna stay put na!