This is just the way I picture it.
As well as the options invite, kin chat etc the option "Proposition" is available. If the offer is accepted and if the parties are one male and one female and if the male does not equip intestines then the female has a one in ten chance of getting pregnant.
Pregnancy reduces her speed to a slow run and ups her food requirements for several hours.
Birth is a hit point risk event that usually goes off with no damage but has a small chance of knocking her back some percentage of her hit points. At that point a baby (two vertical squares) appears in the woman's inventory. She can put it down and walk away if she cares to, or give it to someone else. If she went to the trouble of making it, most likely she will keep it.
The baby has a food bar and requires feeding. As long as it stays in the mother's inventory or in her baby sling (new item similar to quiver and backpack) it gets fed automatically but her food requirements stay higher during this period until the baby has gone through 100 food events. If someone other than the mother has the baby they can also feed it, using milk.
After 100 food events the baby becomes a toddler. At that point as soon as it is removed from the inventory or sling a new graphic appears.