Conception

At what time of the month is a woman most likely to get pregnant? For a woman with a 28-day cycle, the most likely time to get pregnant is right in the middle of the month. Pregnancy can only happen when there is an egg in the Fallopian tube waiting to be fertilized by sperm.

Since the egg is usually produced 14 davs before the next menstrual period, it is fairly easy to calculate the most fertile time. A woman with a 35-day cycle, for instance, would be most likely to get pregnant around day 21. Of course, if a woman has irregular periods, then counting back 14 days obviously won’t work as a simple way of predicting the best date.

But there are other ways of working out when a woman is producing an egg. At this time, a hormone – called progesterone – is released, which causes the body temperature to rise. By taking your temperature every morning, you can see when a persistent rise in temperature takes place – indicating an egg has been released.

Some women notice a change in their vaginal secretions during ovulation – what’s happening is that the mucus from the neck of the womb becomes very much thinner and less tacky than normal. Pain in the pit of the stomach is another sign of ovulation that some women experience. This is due to the release of a little fluid around the egg causing irritation of the lining of the stomach wall.

Once it has been released from the ovary, the egg lives only between 24 and 36 hours. If no sperm reaches the egg by then, it dies and is absorbed into the body’s tissues.

Compared to a woman’s egg production -w usually limited to one every month – the quanti-| ties of sperm a man generates seem enormous. 0 The actual amount produced varies according to 1 demand. Anything between 60 and 200 million w sperms may be ejaculated at any one time, I although if he ejaculates, say, three or four times 3 a day, the amount of sperm may diminish.

The sperm ejaculated during intercourse has been stored in the body for several weeks. The testicles store primitive sperm cells; as they mature, sperms are made and secreted from the testicle, passing into the system of tubes that lead up to the seminal vesicles – a pair of sacs behind the prostate gland. Here the sperms are stored and continue to mature for some weeks.

When a man ejaculates, most of the fluid actually comes from the prostate gland; as this fluid passes down the pipe to the penis, just before ejaculation, a small jet of sperm is squirted into it from each of the seminal vesicles. Tne amount of fluid ejaculated varies from about half a teaspoonful to a tablespoonful.

Provided the sperm count is above 20 million sperms per cubic centimetre, the man is probably periecdy fertile. Below this level, the chances of an active sperm reaching the far end of a woman’s Fallopian tube become rather less. | Outside the 24 to 36 hours period when the egg &™ is present, the chances of getting pregnant are I nil. Since sperm lives only 24 hours, intercourse taking place more than a day or so outside the time of ovulation will not result in pregnancy. This is the basis of the so-called ‘safe period’ or ‘rhythm’ method of contraception; but of course this docs rely on a woman being able to calculate precisely her times of ovulation – which is not always a straightforward matter.

The vast number of sperm released during intercourse are necessary to give a reasonable chance of fertilizing an egg. The sperms move in all directions once they are deposited in the upper end of the vagina, and they have a long way to travel to reach the egg.

Relative to body size, this is equivalent to a man running from London to Oxford in just over an hour!

This gives some idea ot the vast mobility required for the successful sperm to get to the far end of the Fallopian tube. Of the many millions of sperm deposited in the vagina during intercourse, probably only 50 or so will actually make the long and hazardous journey to reach the egg.

As far as we know, there is no chemical kind of attraction or other force that guides the sperm to the egg – until the sperm is very close. So the journey is pardy a matter of chance.

Of the sperms which reach the egg, it is only a single sperm which penetrates the outer layers that causes fertilization. Once the sperm head has passed into the egg, the outer layers change to form an impenetrable block to stop any other sperm entering. The of the sperm is the part which contains the genetic material from the father; once this has fused with the egg, the new embrvo is provided with all the vital genetic’blue prints’ from the mother and father in equal amounts.

Though getting pregnant is a chancy business, it can be achieved without the penis actually penetrating the vagina. Sperm deposited around the lips of the vagina by merely placing the penis between a woman’s legs, may travel upwards through the cervix and on into the uterus and Fallopian tube.

The chances of this happening are rare, and of course conception is much less likely than il the sperm is deposited close to the cervix. But there are many instances of pregnancies in girls who are virgins who have had ‘intercourse’ between the thighs.

There are very few ways in which you can influence nature in this. Of course, as already explained, intercourse has to take place at the time of ovulation to result in pregnancy, but there are also some variations in technique which may slightly improve the chances of the sperm reaching the egg.

If a woman is particularly keen on getting pregnant, she might try to stay lying on her back after intercourse, and falling asleep in that position. This should minimize the amount of semen which passes down the vagina and escapes, and the pool of semen in the vagina will bathe the cervix for much longer than usual, thus slightly increasing the chances of sperm travelling up through the cervical canal. But it’s doubtful just how big a difference this makes and, in any case, most people move in their sleep to adopt whatever position their body prefers.

Some people say that the quantity of sperm ejaculated during intercourse can be increased.