unmarried_mother_pregnancy_effect

unmarried_mother_pregnancy_effect = {
	add_trait_force_tooltip = pregnant
	add_fornicator_trait_or_nothing_effect = yes
	hidden_effect = {
		set_known_bastard_on_pregnancy = yes #The bastard status is already known since the mother is unmarried.
		if = {
			limit = {
				NOT = {
					any_owned_story = {
						type = story_peasant_affair
						var:peasant_character = scope:mother.pregnancy_real_father
					}
				}
			}
			trigger_event = { #This parses whether the mother is planning to confess to a real_father, and checks if there are characters out there who should suspect that they might be the real father
				id = adultery.1101
				days = 20
			}
		}
	}
}

As written in game/common/scripted_effects/00_pregnancy_effects.txt.