Yeah, I can only pass the JLPT 4 at the moment, and thus have years of study to go before I can truly understand what is going on in the game.
To make her pregnant with a "mysterious baby", you can go to the menu (press ESC), choose items (first option), then choose the first item, which is the Debug Mode. Go to the third option on the menu that pops up. Then, choose the bottom option three times. (The bottom option means "next" and takes you to the next set of options.) There, choose the second option, and there you go, she's pregnant and ready to give birth.
She can give birth two different ways. One way is to just have her sleep at an inn. She'll give birth at the respective in. The location may be different (on a bed vs. on a toilet), but the dialogue is identical.
The other place would be at the doctor's in the large city. To go there, talk to the old naked man at the bottom of the town and choose I believe the second option. From there, head up and to the left for the next screen. The building to the left of you is the doctor's office. You know you are in the right spot if you are in a small room with a woman in a white coat that has her own picture come up when you talk to her. Choose the top option (I believe you ask for a check-up.) and then choose the top option again (Literally, "I want to give birth.") Choose the top option one more time, and the scene begins. For some strange reason, no matter what type of baby it is, the crowning pictures did not appear for me. The birth pictures I posted here were edited by myself by looking through the game files, not pulled from the game itself.
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