2,226. Chalalim Under Rabbinic Law

Hilchos Issurei Biah 19:7

If a kohein marries a pregnant divorcee, regardless of whether it’s his child or someone else’s, and she gives birth after becoming a chalalah, the child is halachically fit because it wasn’t conceived through the prohibiting relations.

Hilchos Issurei Biah 19:8

We have already discussed how a woman who has performed chalitzah is prohibited to marry a kohein under rabbinic law. Accordingly, if a kohein is intimate with such a woman, she is rendered a chalalah and her children will be chalalim under rabbinic law. Conversely, if a kohein is intimate with one of the secondary relations, both she and his children with her are halachically valid because these prohibitions apply to everyone and are not unique to kohanim.