Common Terminologies of Obstetrics and Pregnancy
This document defines key terms related to pregnancy, including gravida, gravidity, multipara, nullpara, parity, preterm, term, and viability. It explains that gravida refers to a pregnant woman, gravidity is the number of pregnancies a woman has had, and multipara and primipara describe women who have had multiple or one previous pregnancy reaching a viable gestation.
Understanding Gravidity and Gravida
Gravida refers to a pregnant woman. Gravidity refers to the number of times a woman has been pregnant, regardless of whether the pregnancies were interrupted or resulted in a live birth. Women are classified based on their pregnancy history as follows:
- Nullgravida: is a woman who has never been pregnant.
- Primegravida: A woman who is pregnant for the first time, or who has been pregnant once.
- Multigravida: is a woman who has been pregnant more than one time.
Defining Parity and Delivery History
Parity is the number of pregnancies in which the fetus or fetuses have reached viability when they are born, not number of fetuses like twins or whether the fetus is born alive or stillborn. Parity classification includes:
- Nullpara: A woman who has never carried a pregnancy beyond 20 weeks (para 0).
- Primipara: A woman who has had one pregnancy that resulted in a fetus that attained a weight of 500 g or a gestational age of 20 weeks, regardless of whether the infant was living at birth or whether it was a single or multiple birth.
- Multipara: A woman who has had two or more pregnancies resulting in potentially viable offspring.
- Grand multipara: A woman who has completed more than five pregnancies to the stage of fetal viability.
Gestational Age and Stages of Fetal Development
Other terms like preterm and post-term specify gestational age ranges, while viability and term indicate stages of fetal development.
Preterm refers to the pregnancy that has reached 20 weeks but before completion of 37 weeks of gestation. According to the WHO, there are sub-categories of preterm birth, based on gestational age:
- Extremely preterm: <28 weeks.
- Very preterm: 28 to <32 weeks.
- Moderate to late preterm: 32 to <37 weeks.
A term pregnancy is a pregnancy from the beginning of 38 weeks of gestation to the end of 42 weeks of gestation. A pregnancy that goes beyond 42 weeks of gestation is referred to as post date or post term.
Viability of the Fetus
Viability is the potential of the fetus to survive outside the uterus after birth, natural or induced. This is generally considered to be about 22 to 24 weeks of gestation since last menstrual period or fetal weight of greater than 500 g.
Summary Table of Obstetric Terms
| Term | Definition |
|---|---|
| Gravidity | Number of times a woman has been pregnant. |
| Parity | Number of pregnancies reaching viability (at least 20 weeks). |
| Viability | Potential to survive outside the uterus (22-24 weeks or >500g). |
| Preterm | Pregnancy between 20 weeks and 37 weeks. |
| Term | Pregnancy from 38 weeks to the end of 42 weeks. |
| Post-term | Pregnancy going beyond 42 weeks of gestation. |