No instant-baby cheat exists. Pregnancy follows a fixed timeline. However, you can accelerate aging:
aging off — Freezes all Sims' ages.aging on — Re-enables aging.boolProp aging.growup_faster true — Dramatically speeds up aging (children become teens quickly).boolProp testingcheatsenabled true — Shift-click Sim → Spawn → Tombstone of L and D → More → Speed Up My Pregnancy (debug object).Caution: aging.growup_faster affects every Sim in the neighborhood. Use aging off after desired Sim ages up.