What does the medical abbreviation G1 P0 mean?

G= gravid, pregnant

P= para, carried to term

G1P0 is a woman who has had one pregnancy and no live births. She may be a pregnant woman who has not given birth yet, or a woman who had been pregnant once and had a spontaneous or therapeutic abortion. If she is pregnant, when she does deliver, she will usually be G1P1 (or G1P2 if twins, etc.)