Hello Eroism, this idea came to me after i've played other games with monster pregnancy mechanic :
1. Leah can actually get pregnant (through fertilization) instead of her just being an incubator for insects to lay and hatch eggs inside her body why not have her get fertilized by some creatures.
2. Leah can get pregnant by Oniku and be able to raise her child (like breastfeeding or etc) .
3. A slug or worm can infect Leah’s rectum and become a parasite.
4. Safe days and risky days for Leah to get or prevent pregnancy.