Which episode Little House on the Prairie Laura pregnant?

Laura Ingalls Wilder, the character on whom the "Little House on the Prairie" series is based, never became pregnant in the books. The television series, however, took liberties with the source material and created a storyline where Laura and Almanzo become parents.

The episode where Laura becomes pregnant is Season 7, Episode 22, titled "The Letter." This episode introduces the idea of a new baby, but the pregnancy itself is not explicitly shown.

The series then follows Laura through her pregnancy and ultimately the birth of their daughter, Rose.

It's important to note that this storyline is a fictional addition to the original story, and it's not based on real events in Laura Ingalls Wilder's life.