Women came to Ishikawa's ward, gave birth, and abandoned their children. One woman had a terrifying and horrible solution in her own right. That solution was infanticide, or the crime of killing a child within a year of birth.

Sources:

Miyuki Ishikawa - Wikipedia

Miyuki Ishikawa, The 'Demon Midwife' Who Killed 100 Babies (allthatsinteresting.com)

Miyuki Ishikawa | Murderpedia, the encyclopedia of murderers

Miyuki Ishikawa - Absolute Crime

Details You Should Know About Serial Killer Miyuki Ishikawa (grunge.com)