Objectives: Unwanted intrusive thoughts (UITs) of intentional infant-related harm are common among birthing parents. Evidence to date has failed to find any association with physical aggression toward the infant. However, the relationship between UITs of infant-related sexual harm and sexual behaviors toward the infant has yet to be assessed. This is the purpose of the current study. Methods: Data were collected from February 9, 2014, to February 14, 2017, via a prospective, province-wide, unselected cohort of N = 763 English-speaking birthing parents, n = 502 of whom provided data for the current analysis. Interview assessments of UITs of infant-related sexual harm were administered at approximately 7 weeks postpartum and 4 months postpartum. Sexual harming behaviors toward the infant were assessed via an anonymized questionnaire at the end of the study. Results: UITs of infant-related sexual harm were reported by 9.2% (n = 38; 95% CI, 6.6-12.4) of participants. We found no evidence of an association between UITs of this nature and sexual behavior toward one's infant (Fisher exact, P = 1.00). Only 1 participant reported engaging in sexual behavior toward their infant, and they did not report any UITs of infant-related sexual harm. Conclusions: Study findings add to growing evidence that UITs of infant-related harm are common, and when these thoughts are unwanted and intrusive, they are not associated with an increased risk of actually harming one's infant. Although findings suggest that this is also true for UITs of infant-related sexual harm and sexual behavior, due to the small sample employed in this research, replication with a larger sample is needed.