Question

describe the events of pregnancy and birth

Answer 1

Describe the events of pregnancy and birth

Pregnancy:

Pregnancy is the period between the egg fertilization and the child birth of the individal. Gestation periods varies among different animals and it is about 266 days in humans. A matured oocyte becomes zygote when fertilized. The developing embryo should get implanted in the uterine wall within 7 days of time by travelling through the oviduct to the uterus. The zygotes which fail to achieve this will eventually die. The blastocyst of the develops into the endometrium and the chorion is triggered to release the human beta chorionic gonadotropin (β-HCG) hormone to keep the corpus luteum in active state to ensure the progesterone level which will hold the endometrium of the uterus for the support of the developing embryo. The basic pregnancy test is depend on the level of β-HCG in urine or serum. The gestation has 3 equal trimesters.

First trimester: first two to four weeks during when the nutrition and waste are handled by the endometrial lining through diffusion. Placenta forms when the outer layer of the embryo begins to merge with the endometrium which then acts as a passage for nutrients and waste from mother and growing fetus. Development of internal organ begins.

Second trimester: Grow about 30cm and the organs continue to develop. The first movement occurs/felt by mother.

Third trimester: Fetus grow till 3 to 4 kg and organ development continues till birth. Most rapid phase of growth.

Labor and birth:

During parturition, the physical efforts of expulsion of the fetus and the placenta from the uterus is called as labor. The triggering of oxytocin secretion occurs at the end of third trimester. It is characterized by the reorientation of baby and the head engaging the cervix or uterine opening. This results in stretching of cervix and release of oxytocin by positive feedback mechanism which causes smooth muscle contraction in uterine wall. It further increases the release of prostaglandins to increase vigorous contraction to produce more intense and forceful contractions. The stages of labor are:

Stage 1: Cervix thins and dilates to expel the baby and placenta. Cervix dilation is about 10 cm.

Stage 2: Baby expelled from uterus. Uterus contraction at vigorous pace.

Stage 3: Passage of the placenta after the baby has been born and disengagement of the organ from the uterine wall.