No they don't. Mammals give birth, it's one of the defini g characteristics of the Mammalian Order, except for the 2 types of monotremes.

Seahorses are fish. They belong to the class of Osteichthyes (bony fish) and the genus Hippocampus.

Fish lay eggs as a defining characteristic of their class.

Female seahorses lay eggs. Male seahorses then fertilize the eggs. Lastly, the male collects the fertilized eggs into his pouch to protect them from predation. The eggs hatch inside the male's pouch but at no point is the male giving birth.

This is middle school biology.