Over the past year, I've been trying to master that infinitely confusing subject, gravidity & parity notation. Gravidity refers to the number of pregnancies; parity to the number of births. I won't get into all the subjectivities of the subject (such as "when does a miscarriage become a stillbirth," "when does preterm become term," etc.) because we'd be here all night if I did! (Also, my friend Kathy has already covered the subject extensively here.)
Anyhow, there are three main methods of notation for gravidity/parity (at least, that I know of!), which are as follows. I will use myself as an example: I have had three pregnancies, resulting in one miscarriage, one term birth and one not-yet-finished:
(1) G(x)P(y) - Number of pregnancies followed by number of births.
I am a G3P1 (three pregnancies, one birth)
(2) G(x)P(y)A(z) - Number of pregnancies, number of births, number of abortions (either spontaneous, i.e. miscarriages, or induced)
I am a G3P1A1 (three pregnancies, one birth, one spontaneous abortion)
(3) G(x)P(TPAL) - Number of pregnancies, and then "term births," "preterm births," "abortions" and "living children"
I am a G3P1011 (three pregnancies, one term birth, zero preterm births, one spontaneous abortion, one living child (counting only born children))
Anyhow, I am reading one of Anne Frye's midwifery texts, and she lists two further steps for individualizing this notation, both of which I find very helpful. Here is the method she lists:
That may look confusing, but it's not! It's just the TPAL method with two additions -
(1) After the aborta notation, she adds an "s" or an "i" to indicate whether an abortion was spontaneous (miscarriage) or induced (elective). This seems eminently sensible to me, as the mental and physical history and risk factors of a woman who has had five miscarriages are completely different than one who has had five elective abortions.
(If a woman has had both types of abortions, then they would be listed separately. For example, a woman who has had one term birth, one miscarriage, and one induced abortion would be a G3P101s1i1)
(2) At the end, she adds the number of multiple births in parentheses if there have been multiple births (each set of multiples counts as one, i.e. twins count as one birth, not two)
Thus, I would be a G3P101s1 - three pregnancies, one term birth, zero preterm births, one spontaneous abortion, one living child, no multiple births
The only thing that the notation is still missing, in my humble opinion, is a notation for cesarean vs. vaginal births - a very important distinction, as a lot of risk factors and labor patterns will depend upon this! For example, a friend of mine recently had her fourth baby, a VBA3C. Thus, although she was a G4P3 (or a G4P3003) and would thus be expected to have a fast and easy labor, she in fact had a labor like a primip (first-time mom) because it was her first time through labor and birth.