The news of Midori's pregnancy became known in manga volume 36. In it, Shin-chan and Nene chase after their teacher, who goes to the gynecologist where they hear the good news.
She was born when Midori was going to give back a book she borrowed from Misae, when she arrived at Nohara's house, she started to feel labor pains. Luckily, the landlady of Matazuresou was happening to be near by chance and helped Midori give birth. This happened in manga volume 39.
Sometime after being born, Ishizaka starts to give more attention to Momo than Midori, this makes Midori jealous.
- In Japanese, Momo is a common name, and also means "peach". The word momo in Japanese can be 桃 (peach) or 腿 (thigh). Shin Chan says that if Momo gets fat it will be a 太腿 (hutomomo, which means front thigh, while huto separately is fat). That horrifies Midori and promises that he will not let his daughter fatten.