Obstetrics

Obstetrics (from the Latin obstare, "to stand by") is the surgical specialty dealing with the care of a woman and her offspring during pregnancy, childbirth and the puerperium (the period shortly after birth). Almost all modern obstetricians are also gynaecologists; see Obstetrics and gynaecology.

Terms and definitions

• embryo - conceptus between time of fertilization to 10 weeks of gestation
• fetus - from 10 weeks of gestation ot time of birth
• infant - time of birth to 1 year of age
• gestational age - time from last menstrual period (LMP) up to present
• first trimester - up to 14 weeks of gestation
• second trimester - 14 to 28 weeks of gestation
• third trimester - 28 weeks to delivery
• viability - minimum age for fetus survival, ca. third trimester
• previable infant - delivered prior to 24 weeks
• preterm infant - delivered between 24-37 weeks
• term infant - delivered between 37-42 weeks
• gravidity (G) - number of times a woman has been pregnant
• parity (P) - number of pregnancies with a birth beyond 20 weeks GA or an infant weighing more than 500 g
• Ga Pw-x-y-z - a = number of pregnancies, w = number of term births, x = number of preterm births, y = number of miscarriages, z = number of living children; for example, G4P1-2-1-3 means the woman had a total of 4 pregnancies, of which 1 is of term, 2 are preterm, 1 miscarriage, and 3 total living children (1 term + 2 preterm).