TY - CHAP M1 - Book, Section TI - Chapter 6. Normal Pregnancy and Prenatal Care A1 - Bernstein, Helene B. A1 - VanBuren, George A2 - DeCherney, Alan H. A2 - Nathan, Lauren A2 - Laufer, Neri A2 - Roman, Ashley S. PY - 2013 T2 - CURRENT Diagnosis & Treatment: Obstetrics & Gynecology, 11e AB - Pregnancy (gestation) is the physiologic process of a developing fetus within the maternal body. Several terms are used to define the developmental stage of human conception and the duration of pregnancy. For obstetric purposes, the gestational age or menstrual age is the time elapsed since the first day of the last normal menstrual period (LNMP), which actually precedes the time of oocyte fertilization. The gestational age is expressed in completed weeks. The start of the gestation (based on the LNMP) is usually 2 weeks before ovulation, assuming a 28-day regular menstrual cycle. The developmental or fetal age is the age of the conception calculated from the time of implantation, which is 4 to 6 days after ovulation is completed. The menstrual gestational age of pregnancy is calculated at 280 days or 40 completed weeks. The estimated due date (EDD) may be estimated by adding 7 days to the first day of the last menstrual period and subtracting 3 months plus 1 year (Naegele's rule). SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/12/11 UR - obgyn.mhmedical.com/content.aspx?aid=56964326 ER -