Bringing about a pregnancy
After ovulation, the egg cell is capable of being fertilised for only 12-18 hours per cycle. For this reason, the timing must be exactly right for pregnancy to occur. Because a woman only ovulates once per cycle, she is therefore only fertile for fourteen days per year if she has relatively short 26 day cycles!
If the egg cell is not fertilised within the few hours that it is capable of being fertilised, it dissolves slowly and allows menstruation to begin two weeks later.
This does not mean, however, that a couple has to sleep together within this very short period of 12 - 18 hours per cycle in order to get pregnant. The lifespan of sperm cells can stretch up to 5 days. Male sperm cells can survive in a viable fertilising state and wait for ovulation (under optimum conditions) for up to 5 days inside a woman’s body.
When a man ejaculates, several million sperm enter the vagina and immediately make their way inside the woman. If they find suitable conditions, it is only a matter of a few minutes before the first sperm cells pass the mouth of the uterus and enter the uterus itself.
After sexual intercourse the sperm cells swim, surrounded by cervical mucus, into the uterus and then into the outer ends of the Fallopian tubes, where fertilisation can occur. This is where they wait for the egg cell.
Assisted by the rhythmic contractions of the uterus, some of the sperm cells enter into the Fallopian tube. The remaining sperm make themselves comfortable in the folds of the uterine lining and after some time has passed, begin their own journey into the Fallopian tubes. Therefore, a large number of sperm cells arrive little by little in the Fallopian tubes.
If the women has not begun ovulating, the sperm cells wait for the egg cell for up to five days.
Usually, several dozen sperm cells simultaneously succeed in penetrating the protective wall of the egg cell, but only one single sperm is capable of penetrating the egg cell. This sperm cell’s membrane then fuses with the egg cell’s membrane. Directly after this occurs, the egg cell’s membrane hardens in order to block the entry of any other sperm.
The sperm that has penetrated the egg cell is crucial in determining the sex of the baby. If the sperm is carrying an X-chromosome, it will be a girl. If it is carrying a Y-chromosome, it will be a boy.
Very few couples analyse their fertility and reproductive cycles before they begin pregnancy planning. Often, their previous forms of hormonal contraception cause them to forget about the natural cycle that occurs on a monthly basis. For this reason, knowledge of cycle phases, fertile days or ovulation tends to be minimal.
One of the most important facts to take away from this page is that having sex a few days before ovulation can bring about a pregnancy.