Do mammals give live births or do they lay eggs?

Answer 1

By definition, mammals have live young, with the exception of the three species of monotremes.

These include the platypus and the short-beaked echidna, native to Australia, and the long-beaked echidna, native to New Guinea. These animals lay eggs, but still feed their young on mother's milk.

Eutheria (placental mammals) and marsupials do not lay eggs.
Some mammals lay eggs but some give birth to young alive.

Answer 2

Mammals mostly give birth to live young.

Mammals are divided into three groups. By far the largest group is the placental mammals, all of which have live birth. The next group is the marsupials, which also give live birth, although the young are extremely undeveloped and, for the most part, must continue their development in a pouch, or marsupium.

The smallest group is made up of the monotremes. Monotremes, which include just the short-beaked echidna, long-beaked echidna and the platypus, lay eggs, but are still classified as mammals because they feed their young on mothers' milk.

Answer 3

The vast majority of mammals give live birth. However, monotremes do lay eggs. There are only two monotremes - the platypus and the echidna.