Jenny suddenly cried out in pain. "What was that?" Jeff asked.
"I don't know! I've never felt anything like it!" Just then, she cried out again. "I need to lie down again." She continued to have these abrupt pains every few seconds.
Jeff noticed that her pussy lips were being forced apart, and stretched. "Jenny, I think, those are contractions! I think you're going to give birth!"
"Oh, God, this hurts!" she said. "I'm never letting you cum inside me again!"
"When I last used the Chronivac on you, one of the changes I had to make was for your pussy to be able to stretch a huge amount, in order to accept the enormous size of my, I mean our, cock at that time," Jeff told her. "Hopefully that increased stretchiness will help you now."
After a few minutes, Jeff could see that her pussy lips were stretching around the top of a head, even between contractions. "You're crowning," he said. "Try to push it out!"
"I've _been_ trying!" she replied angrily. "You did this to me! I hate you!"
A few minutes later, after a lot of groaning, she pushed the entire head out, leaving her pussy lips not quite as tight around a neck. Jeff looked at the head, and brushed hair from its face for a better view. "Why... it's you!"
"Duh!" yelled Jenny. "Thank you Captain Obvious! You ejaculated _me_ out into my pussy, so who else would... " She screamed, then continued. "... come out of there?"
"I guess you thought this through much more than I did. But then, why did you let me come inside you?"
"Well, we were having fun, and that part felt great," she said before screaming again. One shoulder was now sticking out. She kept pushing, and screaming, but clearly her shoulders were too wide to emerge from her pussy. Each time she screamed, a scream emerged from the mouth of the body she was giving birth to, as well. Her body. Her other body.
She kept at it, and eventually her pussy lips stretched even wider, and the other shoulder came out. "I used to like it that I have big bust and hip measurements. Doesn't seem so great now!" She kept pushing, with little sign of progress, but then suddenly her body rapidly slid out to her waist. an umbilical cord stretching out from the pussy to the belly button.. "Thank god!" she said. "Hopefully after the hips, the rest will be easy."
She had to work longer at pushing the hips out, but finally did. As she expected, the rest was easier. Once the entire body was out, she delivered the placenta, which was huge. "I guess a full-grown adult body would need a big placenta," she said. "Well, don't just stand there gawking. Cut the cord, and slap the 'baby' to start it breathing."
"I have a knife, but I don't have anything to clamp the cord. I don't think clothes pins would be strong enough," Jeff said. He typed something into the Chronivac, and the cord fell off, leaving a fully healed belly button. He looked at her face, then at her other face. She was right, the body she just birthed was not breathing, and starting to turn a bit blue. He slapped that body's ass hard. The eyes sprung open, and both bodies yelled, "Ow!" Jeff saw that the newborn adult body was now breathing. He reached out and put his arms around her. The new her. And the old her hugged them both.