This is the Archived Desktop Edition. You should be transferred to the Newest Edition for Desktop and Mobile within 2 seconds. |
|||||||||
Lesson 2: Embryology and Fetal Development |
|||||||||
2-8. FETAL GROWTH AND DEVELOPMENT Growth refers to an increase in size. Development is the continuous process by which an individual changes from one life phase to another. These phases includes the prenatal period and the postnatal period. Fetal maturation takes place in an orderly and predictable pattern. The physicians refer to the age of a pregnancy as lunar months. The lunar months corresponds to the usual length of the menstrual cycle, in this respect, it is easier to calculate. A lunar month is a period of four weeks (28 days) and a trimester is a time period of 3 months. a. First Trimester. During the first three months of pregnancy, the product of conception grows from the just-visible speck to the fertilized ovum to a lively embryo. At the end of the first trimester, the following changes have or are occurring:
b. Second Trimester. During these months (4th, 5th, and 6th) the fetus grows fast. At the end of the second trimester, the fetus:
c. Third Trimester. At the end of the third trimester (7th, 8th, and 9th month), the fetus:
NOTE: Lightening is defined as the sensation of decreased abdominal distention produced by the descent of the uterus into the pelvic cavity. This usually occurs two weeks before the onset of labor.a. The length of pregnancy varies greatly. Nevertheless, the normal duration of pregnancy is about 9 1/2 to 10 months (lunar), 38 to 40 weeks. b. It is usually not possible to determine the actual time of fertilization because reliable records concerning sexual activities are seldom available. However, the approximate time can be calculated. c. The estimated date of confinement (EDC) is calculated as follows:
|
|||||||||
The Brookside Associates Medical Education Division is dedicated to the development and dissemination of medical information that may be useful to medical professionals and those in training to become medical professionals. This website is privately-held and not connected to any governmental agency. The views expressed here are those of the authors, and unless otherwise noted, do not necessarily reflect the views of the Brookside Associates, Ltd., any governmental or private organizations. All writings, discussions, and publications on this website are unclassified. © 2007 Medical Education Division, Brookside Associates, Ltd. All rights reserved |