parity /per″itē/ [L, parere, to give birth] , 1. (in obstetrics) the classification of a woman by the number of live-born children and stillbirths she has delivered at more than 20 weeks of gestation. Commonly parity is noted with the total number of pregnancies and represented by the letter P or the word para. A para 4 (P4) gravida 5 (G5) has had four deliveries after 20 weeks and one abortion or miscarriage before 20 weeks. Currently a more complete system is in use: the total number of term infants (T) is followed by the number of premature infants (P), the number of abortions or miscarriages before 20 weeks’ gestation (A), and the number of children living at present (L). This system may be abbreviated as TPAL. 2. (in epidemiology) the classification of a woman by the number of live-born children she has delivered. 3. (in computer processing) the condition of a set of items, either even or odd in number, used as a means for checking errors, such as in the transmission of information between various elements of the same computer.
