Obstetric formula is expressed in terms of gravida, parity live births and abortions (GPLA).
Quick Navigation
Gravida:
Gravida denotes how many times the woman became pregnant. It represents the pregnant states both present in past, irrespective of the gestation.
Para:
Para denotes the previous pregnancies beyond the period of viability (20 weeks of gestations according to WHO). Gravida and para refer to pregnancies not to babies. Eg. Woman delivering twins/ triplets in first pregnancy is still gravida 1 and para 1 (G1P1). A pregnant woman at 28th weeks of gestation with previous history of two abortions can be expressed as gravida 3 and para 1.
Live births:
Delivery after 20 weeks’ gestational age in which any fetal activity is noted is classified as a live birth. The number of babies who had any fetal activity at birth is called live birth.
Abortions:
The number of pregnancies which were terminated before 20 weeks of gestation are called abortions.
Expression of obstetric formula:
A pregnant woman at 30th weeks of gestation with previous history of two abortions and two term delivery.
G5P3L2A2
In most of the centers it is expressed as G5P3+2. The past obstetric history is Summarized by two digits; first one relating viable births and second one relating abortions.
In some of centers it is expressed by four digits connected by dash sign. PA-B-C-D. Where A= number of term pregnancies, B=number of preterm, C=number of abortions and D= the number of children alive at present. So, our obstetric formula will be: G5P2-1-2-2.
