In biology, parity is a technical term that refers to the number of times a female has given birth to a baby.
It can lead to some ambiguity for events occurring between 20 and 24 weeks, and for multiple pregnancies.

Ever wondered if there's something that is used measure the number of times or categorize the pregnancies of women? No? Well, there is such a thing.

This is referred to as a woman's obstetric history.

Obstetrics (from the Latin obstare, "to stand by" wink is the medical specialty dealing with the care of all women's reproductive tracts and their children during pregnancy (prenatal period), childbirth and the postnatal period. Many obstetricians are also gynecologists, meaning they perform in both specialties. In the United States, these physicians are commonly referred to as OB/GYNs.

There are different methods used to categorize or measure a woman's obstetric history.

A woman's obstetrical history is recorded as: number of pregnancies, known as gravida and number of pregnancies carried to viable gestational age , known as parity. Viable gestational age varies from region to region, for example in the UK it is considered to be 24 weeks whilst in the USA; 20 weeks is considered viable.

+ A woman who has never given birth is a nullipara, a nullip, or para 0.
+ A woman who has never completed a pregnancy beyond 20 weeks is also referred to as being nulliparous, a nullipara or para 0.
+ A woman who has given birth one or more times is referred to as para 1, para 2, para 3 and so on.
+ A woman in her first pregnancy and who has therefore not yet given birth is a nullipara or nullip. After she gives birth she becomes a primip.
+ A woman who has given birth once before is primiparous, and would be referred to as a primipara or primip.
+ A woman who has given birth two or more times is multiparous and is called a multip.
+ Grand multipara refers to a (grand multiparous) woman who has given birth five or more times.

Gravida/para/abortus (GPA), or sometimes just gravida/para (GP), is a shorthand notation for a woman's obstetric history.

+ Gravida indicates the number of times the mother has been pregnant, regardless of whether these pregnancies were carried to term. A current pregnancy, if any, is included in this count.

+ Para indicates the number of >20 wks births (including viable and non-viable i.e. stillbirths). Pregnancies consisting of multiples, such as twins or triplets, count as ONE birth for the purpose of this notation.

+ Abortus is the number of pregnancies that were lost for any reason, including induced abortions or miscarriages. The abortus term is sometimes dropped when no pregnancies have been lost. Stillbirths are not included.
Therefore, the history of a woman who has had two pregnancies (both of which resulted in live births) would be noted as G2P2. The obstetrical history of a woman who has had four pregnancies, one of which was a miscarriage before 20 weeks, would be noted as G4P3A1 (in the UK this is written as G4P3+1). That of a woman who has had one pregnancy of twins with successful outcomes would be noted as G1P1.

In Contrast with TPLA, though similar, GPA should not be confused with the TPAL system, which may be used to provide information about the number of miscarriages, preterm births, and live births by dropping the "A" and including four separate numbers after the "P", as in G5P3114. This indicates 5 pregnancies, with 3 term births, 1 preterm birth, 1 induced abortion or miscarriage, and 4 living children.

Gravida status is the number of pregnancies a woman has had. Parity is recorded in the format, T-P-A-L:
is the number of term births (twins and other multiple births count as 1). Term births are those occurring at 37 weeks or beyond.
is the number preterm births (twins and other multiple births count as 1). Preterm births are those that occur after 20 weeks and before 37 weeks.
is the number of abortions (spontaneous or induced) prior to 20 weeks.
is the number of living children.
For example, Gravida and parity are noted here using GTPAL. A woman who has given birth at term once and has had one miscarriage at 12 weeks would be recorded as G2 T1 P0 A1 L1. This notation is not standardized and can lead to misinterpretations.

Who would have thought? Humans tend to be so complicated but I am please to see them do things like this.
Maybe this could apply to animals as well. There might be a different system that works similar to this, but with a different name.

I look further to educating you in the future, so please look forward to my next entry.