|
|
|
| Free E-magazine |
| Subscribe to our Free E-Magazine on Pregnancy. |
| Learn More |
|
|
|
|
|
|
|
|
|
|
|
| Home > Reproductive Anatomy > Pregnancy Calendar
| |
| | Pregnancy Calendar
| |
| |
 From conception to birth, your body will undertake the most amazing process of fertilization, implantation and the development and growth of your baby (or babies). Fetal life begins with the fertilization of the ovum, which occurs about two weeks after your last menstrual period. Your body becomes your baby`s home for the next nine months (or around 40 weeks). The length of the pregnancy, however, is calculated from the first day of your last menstrual period. You will experience a journey of many new physical sensations. Whether this is your first, second, third (or more) pregnancy, your body will react differently to each individual pregnancy.
How do you calculate your due date? Conception or fertilization of the ovum takes place about two weeks after the last menstrual period. So when you are twelve weeks pregnant, your fetus is ten weeks old. To calculate your due date, your point of reference will be the first day of your last menstrual period and the pregnancy lasts for approximately 280 days or 40 weeks from this reference day. If the day of conception is known, due date is calculated by adding 266 days or 38 weeks from the day of conception. To arrive at your due date, you go to a date exactly one year in future from the first day of your last menstrual cycle, subtract three months from it and add seven days. For example, if your first day of last menstrual cycle is September 15, 2006, you go forward to September 15, 2007. Subtracting 3 months, you get June 15, 2007. Adding 7 days, gives you the due date as June 22, 2007.
Normal pregnancies vary in length. It is best to think of your due date as approximate and expect the baby anytime within two weeks before or after that time. Two-thirds of all babies are born within ten days of their due dates.
As pregnancy progresses, the development and growth of the baby/babies in your womb brings about profound physical changes in your body and emotional changes in you and your partner.
Many of the physical changes are caused by specific hormone production:
Human chorionic gonadotropin (hCG), produced by by cells that form the developing placenta, which nourishes the egg after it has been fertilized, by assuring that the ovaries produce estrogen and progesterone until the placenta matures and takes over production of these hormones.
Estrogen promotes the growth of the reproductive tissues by increasing the size of the uterine musculature. It stimulates the growth of the uterine lining and its blood supply, causes increase in the amount of vaginal mucus, and stimulates the development of the duct system in the breasts. The high levels of estrogen in pregnancy may probably influence water retention, subcutaneous fat buildup, and skin pigmentation.
Progesterone inhibits smooth muscle contractions, so high levels of progesterone decrease the frequency of uterine contrac-tions, helping to maintain your pregnancy. Progesterone also slows down or inhibits the contractions of the smooth muscles of other organs-such as the stomach and bowels, bladder and ureters, and walls of the blood vessels-and stimulates the secretion of the ovarian hormone relaxin, which relaxes and softens the ligaments, cartilage, and cervix, allowing these tis-sues to spread during the birth. Finally, progesterone raises your body temperature.
Besides estrogen and progesterone, other hormones that influence growth, mineral balance, metabolism, and corticos--teroid levels are produced in greater quantities and cause many physical changes during pregnancy.
Trimesters divide the pregnancy period into three periods of more or less three months. As you know, the entire gestation period lasts for approximately 40 weeks, from the first day of the last menstrual cycle and delivery
The first trimester is the period of time from the first day of the last menstrual period through 14 weeks of gestation. It is during this period that the embryo undergoes most of its early structural development. Most miscarriages occur during this period.
The second trimester is the period of time extending from the 15th to the 27th week of gestation. During this period the embryo, now known as a fetus, is recognizable as human in form, but is not developed enough to be viable if born.
The third trimester is the period of time extending from the 28th week of gestation to delivery. It is during this period that the fetus reaches viability, and may survive if born prematurely.
| |
| |
|
