This question was recently addressed by an unpublished NC Appellate Court opinion filed on May 17, 2022 in McLane v Goodwin-McLane and Peackock.

Plaintiff McLane and Goodman-McLane (recipient) were married and Peackock was the sperm donor.  All three entered into a written contract where they agreed that the child would be the child of the marriage and that Donor would have no rights and would never file any claim for legitimization, custody, visitation, etc... The deed was done and a baby born.

About 4 years later McLane and Goodman-McLane separated and three months after separation Peacock filed an action for legitimization.  This was met by an action filed by Plaintiff McLane for Breach of Contract.  The trial court ruled against Peacock and found he was barred by contract from having anything to do with the child of McLane and Goodman-McLane.

Peacock appealed and, in an interesting turn of events, Goodman-McLane filed two briefs but never filed an Appellate brief!  The court correctly found her "appeal" to be frivolous.

The Court of Appeals would have none of Peacock's novel arguments.  It ruled squarely on the four corners of the contract and found it was executed freely, voluntarily, with full disclosure and its terms were enforceable. The court further found that as McLane was the legal parent of the minor child, arguments by Peacock, if adopted, would lead to McLane entering into a contract that would have deprived her of her parentage, which would be against public policy.

So the moral of this story is that when we use a sperm donor to create life, we need to have a strong, enforceable contract to protect the parent's rights and ensure the best interest of the minor child.