| Pregnancy lasts for approximately 40 weeks (The pregnancy period may vary from 38 to 42 weeks). For convenience, the term “obstetric month” is used in practice, which is the equivalent to 4 weeks. As a rule, the calendar month is longer. Hence the difference between calendar and obstetric months: Pregnancy lasts for 9 calendar months or 10 obstetric months. Our calendar is maintained according to obstetric months.
From conception up to the fourth week:
1. Ovulation:
Approximately on the 14th day of menstrual cycle, the ovum matures and is ready for fertilization. It comes out of the ovary and falls into the uterine [fallopian] tube, where it remains viable for up to 24 hours; If fertilization does not occur, then ovum degenerates and comes out with the uterine discharges during next.
2. Fertilization:
The sperm contains a substance, which dissolves the membrane of the ovum that allows the spermatozoid to penetrate into it. After this, other sperm cannot penetrate inside. The spermatozoid merges with the ovum and the single cell embryo is formed, the Zygote.
A large quantity of sperm flow back and a portion of spermatozoids, which are already inside the female organism, cannot reach the target but some of them through the cervix of uterus fall into the cavity of the uterus and from there, into one of the fallopian tubes. Here, spermatozoids can remain viable for 48 hrs.
3. Division of fertilized cell:
Moving down along the fallopian tube, the fertilized ovum starts dividing into multiple cells.
4. Movement towards uterus:
The Zygote reaches the cavity of uterus approximately on the 4th day after fertilization. By this time, it resembles a ball containing liquid. The ball is very small and undifferentiated but already contains around 100 cells. In subsequent days, the zygote moves inside the uterus.
5. Implantation:
By the end of the 3rd week, the zygote penetrates into the soft uterine wall. This is called implantation. As soon as the zygote gets securely implanted in the wall, the fertilization process is accomplished. The outer cells of the embryo penetrate into the epithelium of the uterus and join with the blood vessels of uterus to develop into the placenta in the later stages. Other cells develop into the umbilical cord and membranes, protecting the fetus. The inner cells divide into three layers and give rise to the formation of various organs and tissues.
6. Sex of the child:
The sex of the child is determined by the chromosomal set of spermatozoids. The spermatozoid with the male set of chromosomes moves faster but is short-lived in comparison with the female set. Therefore, if the conception occurs in the ovulation period (around 14 days before menstruation) the chances of having a male child increases and the probability of having a girl child increase if the conception occurs 2-3 days before.
7. Expected date of delivery:
The period from the time of conception till the birth of a child should be approximately 266 days. In order to calculate the expected date of delivery (EDD) (in a 28 day menstrual cycle, where ovulation occurs on the 14th day), count 280 days (266+14) from the 1st day of the last menstrual period (LMP). |
This week doctors announced a new fertility treatment technique which will allow them to grow human eggs in clinics. The pioneering technique will take an ovarian tissue with immature eggs from a woman, and freeze them until a woman decides to conceive and have a baby. At that time the immature eggs are cultivated with a special hormone to grow into mature eggs ready for fertilization. Such fertility treatment breakthrough is especially important for business women who are too busy to start a family, but want to make sure they will be able to have a baby later.
