Although often unrecognized by care providers, uncertainty during pregnancy is universally experienced. The antecedents to uncertainty are exemplified with qualitative data from interviews with pregnant women. The following antecedents are discussed: (1) symptom patterns; (2) event familiarity; (3) event congruence; (4) cognitive capacity; (5) structure providers; and (6) credible authority. The importance of exploring uncertainty during pregnancy stems from the relationship between the stress associated with uncertainty and perinatal complications. Negative caregiver reactions to uncertainty that can intensify stress include ignorance, intolerance, and indifference. Suggestions for nursing assessments and interventions during prenatal care are provided.