Is the effect of praying for illness upon one's children erased if the one who made the prayer repents before conceiving them?

If the supplication against the children is made while they are absent, it has no effect. If the intention is to supplicate against them if they are present, then it is an unlawful means to deter from forbidden acts. The Prophet (peace be upon him) forbade supplicating against children for fear of coinciding with an hour of acceptance. Supplicating for harm against a child is considered supplicating for evil. Allah (the Exalted) clarifies in His statement: "And if Allah were to hasten to the people the evil [they invoke] as swiftly as they supplicate for good, their term would have been concluded for them," that it is from His mercy not to answer the supplication of parents against their children in a moment of anger. The saying that a parent's supplication against their child is answered refers to a disobedient child who is excessively rebellious.