​ Thank you for the question on CMS334, Cesarean Birth (PC-02). According to ACOG’s reVITALize obstetric data definitions: Nulliparous is a woman with a parity of zero. Parity is the number of pregnancies reaching 20 weeks and 0 days of gestation or beyond, regardless of the number of fetuses or outcomes. Gravidity is the number of pregnancies, current and past, regardless of the pregnancy outcome. Therefore, the logic will categorize a patient as nulliparous if a patient has parity = 0 (based on ACOG definition of nulliparous) OR Gravida = 1 (to account for current pregnancy, not yet delivered) OR preterm and term births both = 0. If any one of these 3 conditions are met, the patient will be considered nulliparous and will be included in the measure. To answer your specific question, a patient who is Gravida 2, para 0, term 0 and preterm 0 would be considered nulliparous as para=0 and preterm/term births are both 0. See the actual logic below: Singleton Delivery Encounters at 37 Plus Weeks Gravida 1 Parity 0, No Previous Births ( "Delivery Encounter with Gestational Age Greater than or Equal to 37 Weeks"   intersect "Encounter with Singleton Delivery" ) SingletonEncounterGE37Weeks   where ( ( "LastGravida"(SingletonEncounterGE37Weeks)= 1 )       or ( "LastParity"(SingletonEncounterGE37Weeks)= 0 )       or ( ( "LastHistoryPretermBirth"(SingletonEncounterGE37Weeks)= 0 )           and ( "LastHistoryTermBirth"(SingletonEncounterGE37Weeks)= 0 )))           Please let us know if you have additional questions.

According to ACOG, nulliparous refers to a female of reproductive age who has never had a live delivery. Being nulliparous does not mean that a person has never been pregnant. A woman who has had a pregnancy loss or elective abortion is nulliparous. The logic uses Gravida 1 to define nulliaparous.