Even if they did include a pregnancy mechanic, women don't stop functioning the moment they become pregnant. Most women don't even know they are pregnant till they miss their period.
Pregnant women are able to perform normal every day functions up to the early third trimester. Prior to this they can function quite normally, but over exertion may risk a miscarriage. Depending on certain factors relating to the mother, and extenuating risk issues they can continue to perform normally right up till birth. Recovery depends a lot on the difficulty of the labor, but is generally only a few days.
Given the lifespan of a person in Elyria is about 6 months of our time, any period of penalty would be relatively brief. Also the tribes of mann are different then humans, and may have any number of different strengths/weaknesses. They may be able to carry children and give birth with fewer risks and limits of functioning.
I plan to play a female, and I wish they would include some form of pregnancy, as long as they don't make it absurdly penalizing.