In biology and human medicine, gravidity and parity are the number of times a female is or has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These terms are usually coupled, sometimes with additional terms, to indicate more details of the woman's obstetric history. When using these terms:
Contents
Gravidity
In human medicine, "gravidity" refers to the number of times a woman has been pregnant, regardless of whether the pregnancies were interrupted or resulted in a live birth.
Terms such as "gravida 0", referring to a nulligravida, "gravida 1" for a primigravida, and so on, can also be used. The term "elderly primigravida" has also been used to refer to a woman in her first pregnancy, who is at least 35 years old.
In biology, the term "gravid" (Latin: gravidus "burdened, heavy") is used to describe the condition of an animal (most commonly fish or reptiles) when carrying eggs internally. For example, Astatotilapia burtoni females can transform between reproductive states, one of which is gravid, and the other non-gravid. In entomology it describes a mated female insect.
Parity
Parity is the number of pregnancies carried to viable gestational age.
A woman who has never carried a pregnancy beyond 20 weeks is nulliparous, and is called a nullipara or para 0. A woman who has given birth once before is primiparous, and is referred to as a primipara or primip; moreover, a woman who has given birth two or more times is multiparous and is called a multip. Finally, grand multipara describes the condition of having given birth three or more times.
Like gravidity, parity may also be counted. A woman who has given birth one or more times can also be referred to as para 1, para 2, para 3 and so on.
Viable gestational age varies from region to region.
In agriculture, parity is a factor in productivity in domestic animals kept for milk production. Animals that have given birth once are described as "primiparous"; those that have given birth more than once are described as "pluriparous". Those that have given birth twice may also be described as "secondiparous", in which case "pluriparous" is applied to those that have given birth three times or more.
Recording systems
A number of systems are incorporated into a woman's obstetric history to record the number of past pregnancies and pregnancies carried to viable age. These include:
Though similar, GPA should not be confused with the TPAL system, the latter of which may be used to provide information about the number of miscarriages, preterm births, and live births by dropping the "A" from "GPA" and including four separate numbers after the "P", as in G5P3114. This TPAL form indicates 5 pregnancies, with 3 term births, 1 preterm birth, 1 induced abortion or miscarriage, and 4 living children.
Nulliparity
A nulliparous (/nʌlˈɪpərəs/) woman (a nullipara or para 0) has never given birth.
Prolonged nulliparity (/ˌnʌlᵻˈpærᵻti/) is a risk factor for breast cancer. For instance, a meta-analysis of 8 population-based studies in the Nordic countries found that nulliparity was associated with a 30% increase in risk of breast cancer compared with parous women, and for every 2 births, the risk was reduced by about 16%. Women having their first birth after the age of 35 years had a 40% increased risk compared to those with a first birth before the age of 20 years.
Criticism
In humans, it can lead to some ambiguity for events occurring between 20 and 24 weeks, and for multiple pregnancies.