Negotiating the terms of a pregnancy, usually before the pregnancy occurs. The terms in question include but are not limited to: the career aspirations of the prospective parents, their earning potential, housing and location, child care, schools, television-watching regulations, table manners, permissible clothing, and nutrition. Planning can reach absurdly detailed levels, however it's understood that the terms of a preggotiation go completely out the window once the child is born and the parents confront the realities of child-rearing.
Jill: "I want to have a baby."
Jack: "OK, but we can't raise a child in this little apartment."
Jill: "OK, then let's move to a bigger one."
Jack: "We can't afford a bigger place in this city, and anyway the schools are bad. We'll need to move upstate."
Jill: "But my job is here--I won't be able to make nearly as much money upstate."
Jack: "Well, if we're going to have a child you can probably kiss your career goodbye, and I'll have to squeeze in a second job. Maybe I can tend bar at night."
Jill: "OK, but the TV must be off during dinner, and if it's a girl she won't leave the house looking like a hoochie."
Jack: "Deal. Glad to preggotiate with you. Now let's go get you knocked up."