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Dr. Abayomi Ajayi

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Having a baby may seem simple, but the reality of conception and pregnancy is far from simple. On the contrary, it is actually extremely complicated. There are many stages in the process where the chain of events may break down. It’s no surprise that some people experience problems with getting pregnant. In any given month, couples age 28-33 with normal functioning reproductive systems have only a 20-25 per cent chance of conceiving. After six months of trying, only 60 per cent of couples will conceive without medical assistance.


Most of the time, a woman won’t know the exact day she conceived or got pregnant. She may count the start of pregnancy from the first day of the last period. Normally, an egg lives for about 12-24 hours after it’s released. For you to get pregnant, a sperm must fertilise the egg within this time. Sperm can live for up to five days inside the woman’s body. This means, if the couple have sex up to seven days before the woman ovulates, or within a day or so of ovulating, she could conceive. It can be inferred that intercourse few days before ovulation can lead to conception. As long as one sperm remains alive, there is a chance of conception. About 24 hours after ovulation, the risk of pregnancy disappears when the woman’s egg dies.


The steps to conception and pregnancy are quite complex and it’s a miracle that it happens at all. First, the couple must have intercourse every other day around the time of ovulation, because sperm live for an average of 48 hours. Not only must the woman ovulate a mature egg, it must be picked up by a healthy Fallopian Tube; the man must produce sufficient healthy and strongly swimming sperm; the sperm must reach the egg; the egg must change its structure to become a fertilized embryo; genetic material of the embryo must be correct; the embryo must divide correctly to form a blastocyst; and the blastocyst must implant in the womb and be accepted. The wall of the womb must be healthy and ready to allow a fertilised embryo to implant.


This is only just the beginning. Failure of the sperm or egg to make an important connection anywhere along this complicated itinerary will prevent pregnancy from occurring. And to complicate matters, genetic miscoding will often lead to the embryo not implanting, or disintegrating soon after implantation.

At this moment of implantation, pregnancy has officially occurred and the placental tissue begins to secrete a hormone called  hCG. Implantation may take place as early as a handful of days after ovulation or well over a week. On average, one can expect implantation to occur about six to twelve days after ovulation.

It is estimated that 60- 80 per cent of all naturally conceived embryos are simply flushed out in women’s normal menstrual flows unnoticed. And the older a woman gets, the less chance she has of getting pregnant. Women aged 40 and above have only a 5 per cent chance or less of becoming pregnant naturally in any one month.


The process of conception begins quite simply, and then gets really complicated. Every month, the female ovulates one mature egg from one of her ovaries. This egg leaves the ovarian follicle and is ‘captured’ in the end of the Fallopian tube. Here, it will begin to move slowly down the tube towards the womb (uterus). However, for a pregnancy to develop, it must first meet sperm from the male at the same time as it is still held in the Fallopian tube.

So, how does the sperm get to the egg? Good question. A man ejaculates an average quantity of semen, containing between 100 million and 300 million sperm. Less than 100,000 of them manage to pass through the cervix (opening of the womb). Only about 200 will make it through the Fallopian tubes and only one will fertilise the egg.

The sperm leave the man’s penis by ejaculation and are deposited in the vagina high up near the cervix. The sperm immediately begin swimming and some will find their way into the cervix. Sperm have a long journey towards the egg. From the cervix they enter the womb and swim towards the Fallopian tubes. Strangely, the vagina and the womb are not very friendly environments for sperm, but once inside the Fallopian tubes, the ejaculated sperm find their way to the egg. Once they meet, the process of fertilisation begins. Many sperm will bind to the shell of the egg, but only one sperm will be allowed to go all the way through to reach the egg inside the shell.


Sperm can survive for a few days in the female reproductive system. Once the sperm has gained entry to the egg, a complex chain of events occurs over a period of about 16-24 hours. Following this, the egg can now be said to be a fertilised embryo and would normally be at this stage one day after ovulation.

For the next few days, the embryo’s genetic material divides and then enters the blastocyst stage. From the Fallopian tube, the blastocyst enters the womb. Over the next few days, it hatches out of its shell and attaches or implants into the wall of the womb. It will grow and eventually form blood vessel connections with the mother.

This stage of connecting with the womb wall is called “implantation” and is another critical stage in achieving a pregnancy. At this point, a pregnancy test would be positive. The embryo continues to grow and develop the different types of cells and structures necessary to become a baby. The process of conception has occurred and the woman can now be said to be pregnant.

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