Gravidity and parity

In biology and medicine, gravidity and parity are the number of times a female has been pregnant (gravidity) and carried the pregnancies to a viable gestational age (parity). These two terms are usually coupled, sometimes with additional terms, to indicate more details of the female's obstetric history. When using these terms:

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.^{[citation needed]}

In human medicine, "gravidity" refers to the number of times a female has been pregnant, regardless of whether the pregnancies were interrupted or resulted in a live birth. “Gravidity” is an important component of a patient’s reproductive history, as it provides insight into the risk factors that the patient has for pregnancy outcomes, such as risk for gestational diabetes, pre-ecclampsia, spontaneous abortion, preterm birth, fetal growth restriction, and more. The gravidity of the patient is associated with risk for other conditions as well, including risk for breast, ovarian, and endometrial cancer. Knowing a patient’s obstetric history in a prenatal assessment or early in gestation allows the patient to receive early intervention to prevent these associated risks.

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 female in their first pregnancy who is at least 35 years old. Advanced maternal age can be a risk factor for some birth defects.

In human medicine, parity is the number of pregnancies carried by a female for at least 20 weeks (duration varies from region to region, 20 – 28 weeks, depending upon age of viability). If a female carries the fetus to viable age, even if ultimately the fetus is born deceased, this still counts as an instance of parity, as parity is based on the time of gestation prior to a birth, and not the status of the offspring once born.

A female who has never carried a pregnancy beyond 20 weeks is nulliparous and is called a nullipara or para 0. A female who has given birth once is primiparous and is referred to as a primipara or primip. A female who has given birth two, three, or four times is multiparous and is called a multip. Grand multipara describes the condition of having given birth five or more times. Grand multiparity is associated with adverse maternal and neonatal health outcomes.

Like gravidity, parity may also be counted. A female 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.