Simplify the following text for a Grade 5 native English-speaking person.
Original: When Hera discovered that Leto was pregnant and that Zeus was the father , she banned Leto from giving birth on `` terra-firma '' , or the mainland , or any island at sea .
Simplified: When Hera found out that Leto was pregnant with twins by Zeus she was angry . She banned Leto from giving birth on any mainland or island that was known .