She's not in a couple of those episodes, or is just in for a quick scene. But didn't they actually show her early in that season getting pregnant through artificial insemination, only to have her lose the baby in the same episode?

The decision to hide Annie Potts' real pregnancy in Season 6—after explicitly teasing a pregnancy plot—was a choice made by producers to avoid redundancy with their lead-in show, Murphy Brown.

Here is the breakdown of why the storyline was abruptly dropped:

The "Murphy Brown" Problem: Murphy Brown aired directly before Designing Women on Monday nights and featured a major storyline where the lead character was also single and pregnant. Producers felt that two shows in a row featuring single-motherhood storylines would be repetitive and "too similar".

Avoiding the "Bandwagon": At the time, the Murphy Brown pregnancy was a massive national controversy (famously criticized by Vice President Dan Quayle). The Designing Women producers did not want to appear as though they were leeching off that publicity or hopping on a "single motherhood bandwagon."

Character History: The show had recently explored pregnancy with the character Charlene (Jean Smart). Showrunner Linda Bloodworth-Thomason stated that because they had already investigated those issues with Charlene, they didn't want to be "married" to another pregnancy plot so soon.

The "Un-Pregnant" Pivot: In the episode "Picking a Winner," Mary Jo successfully undergoes artificial insemination and gets a positive pregnancy test. However, the writers quickly pivoted, having her lose the baby almost immediately to close the door on the arc.

Hiding the Bump: For the remainder of the season, Annie Potts had to wear baggy clothes, carry large purses, and stand behind furniture (like desks or the kitchen counter) to hide her actual physical condition. She eventually missed the final episodes of Season 6 to give birth.

Annie Potts later expressed disappointment with the decision, arguing that as a show about women's issues, they should have "taken the bone and run with it" rather than hiding it.