From: Rabbi Moshe Sofer
To: Unknown recipient
A Kohen's wife gave birth too soon after the wedding, and while the husband denied paternity he wished to remain married. The Chasam Sofer rules that beis din cannot compel a divorce, distinguishing bari u'bari in monetary and fetal-status contexts from the woman's personal kashrus where it is irrelevant, and holding that since she claims relations with a kosher person — which the husband does not contradict — her status is fully intact and the stringency of yuchsin has no foothold.
Source: Shu"t Chasam Sofer EH I §29