Normal Fertility

What is normal fertility ? This is a very simple question which is frequently asked but to which there is no simple and straightforward answer. It depends upon many factors and is essentially a very personal question to which the answer is different for every individual according to her history, age, physique, symptoms as well as her psychological background, the fitness of her husband, the frequency of intercourse and the stresses and strains of every day life.

Broadly speaking, fertility varies with age, upon which usually depends such factors as the frequency of intercourse and health. The normal healthy young woman in her early twenties who is having intercourse three or more times per week has a chance of becoming pregnant according to the following:

One month 30 percent
Two months 45
Three months 55
Six months 65
One year 80
Two years or longer 85

The above figures refer to an apparently fit, healthy young woman married to a fit and apparently healthy man, but of course, while most people tend to consider fertility or infertility to be a female problem, the male is totally responsible in 30 per cent and partially responsible in about 50 per cent of instances of infertility.

Age of the Woman

Age is undoubtedly linked to fertility. There are many reasons why this is so and in a modern civilized society the age at which pregnancy is desired is usually somewhat different from the age at which marriage takes place. Nevertheless, if a woman wishes to become pregnant, the table below gives a rough idea of her chances of success depending on her age:

Under the age of 20 95 percent
20-25 94
26-30 89
31-35 83
36-40 76

FertilityFertility begins to fell after the age of 25, but the decline is comparatively slow until the age of 30, when it accelerates and increases quite rapidly from the age of 3 5 onwards. There is a strange phenomenon associated with the fertility of women which has long been known as the ‘last fling of the ovary’. This is a sudden and unexplained rise in fertility at about the 39th year of life, which accounts for many an unexpected pregnancy in the late thirties and is usually the reason why the mother of teenage children, or even the young grandmother, suddenly finds herself in a state of unexpected pregnancy.

Age of the Man

The effect of age upon male fertility is not well understood, but it does not appear to obey the same dramatic changes that affect women. There seems to be a gradual decline in the fertility of the male from a fertility rate of 95 per cent or more at the age of 20, to a 10 per cent fertility rate at the age of 60. Insufficient attention has been paid, especially in Great Britain, to the part that the male may play in infertility and, whereas until fairly recently it has been accepted that the male may be either fertile or infertile, it is now recognized that degrees of fertility in the male may play a much more important part than has been considered in the past.

Frequency of Sexual Intercourse

The ease with which a woman becomes pregnant is generally related directly to the frequency of sexual intercourse. There are, of course, many factors which influence the frequency of intercourse. Firstly, age, in so far as the young have intercourse more frequently than the old; then pregnancy is more likely because the young are more fertile than the old. Also there is the simple fact that if sexual intercourse occurs four times a week, sperms will almost always be present in the outer part of the Fallopian tube waiting for ovulation to occur, whereas if sexual intercourse occurs only once a week, the exact date of ovulation may be missed for several consecutive months.

It has often been suggested, and it is probably true, that a man’s seminal count and also his potency will vary according to his general health as well as the number of times he has intercourse. If he is fit and well intercourse will certainly be more frequent than when he is ill or tired.

Emotional Factors

Emotional factors, psychology and personality all play a large part in the process of conception. Psychological factors, stress, strain, tiredness and overwork can all lead directly or indirectly to unsatisfactory intercourse. These factors, of course, are more obvious in the male who may be either unwilling to have intercourse or may be incapable of maintaining a satisfactory erection.

It is when normal and satisfactory intercourse is taking place and all investigations have failed to reveal any abnormality that the really unknown psychological and emotional factors are evident. It is quite common for a couple who, having tried desperately to become pregnant over a number of years, have eventually decided on adoption and the wife has then become pregnant even before the adoption papers can be finally signed. These and many other examples do indicate that a relief from mental strain, anxiety and worry can occasionally play a vital part in conception.

Old Wives’ Tales about Fertility

Painful periods. It has often been stated that painful periods may give rise to infertility later in life and the more painful a girl’s periods, then the greater the difficulty will she have in becoming pregnant and the more likely is she to miscarry. Nothing could be further from the truth. The spasmodic pain of which so many women complain on the first or second day of their normal period shows that their ovaries are working normally and there is no truth whatever in the suggestion that they will have any difficulty either in conceiving or in retaining a pregnancy. One might add here that the converse of the above is not true. Women can ovulate quite normally without having painful periods and, while painful periods are a sign of ovulation, 95 per cent of the women who do not have pain with their periods are, in fact, ovulating perfectly normally.

Irregular periods. Some women always have and always will have irregular periods. The only problem posed by an irregular menstrual cycle is the difficulty in deciding the exact date of ovulation. If sexual intercourse is occurring more than twice a week the exact time of ovulation is immaterial anyway. People who always have irregular periods are just as fertile as those who always have regular periods.

Infrequent periods. Women who have infrequent periods are just as fertile as those who have regular periods, the only disadvantage being that the woman who has only three or four periods a year has only three of four chances a year of becoming pregnant instead of thirteen as in the woman who has a period every 28 days.

Retroversion of the uterus. Approximately 17 per cent of girls are born with their uterus in a tilted or backward position. This is perfectly normal for them and their uterus will remain in this position for the whole of their lives. It is not associated with any difficulty in becoming pregnant nor is it associated with any increased tendency to miscarry. This so-called congenital type of retroversion is different from the acquired type of retroversion in which the uterus is tilted backwards as a result of disease or infection in the pelvis. It is then the disease or infection which limits the fertility and not the retroversion. The position of the uterus does not matter.

Family history. There is no truth in the stories that just because your mother had some difficulty in becoming pregnant or that she miscarried frequently, you are likely to do so, nor is there any truth in the suggestion that because your sisters have suffered from problems then you are likely to as well.


When should you see your doctor to ask him about your fertility ? If you have any reason whatsoever to doubt your own fertility, or if you have any gynaecological symptoms that you consider to be abnormal, such as discharge, pain, irregularity or heavy bleeding, then you should consult your doctor about these.

If you do not have any abnormal symptoms, opinions on seeking advice about fertility are divided. The traditional school of thought that advice should not be sought until pregnancy has failed to occur after two years of normal intercourse without any attempts at contraception, is the answer that will be found in most medical textbooks. A lot of young people today, however, are not satisfied with this for two very good reasons. Firstly, they consider that if pregnancy has not occurred, two years is too long to wait before seeking advice and, secondly, they believe that there is always a chance that some abnormality may be present of which they are unaware because it is not causing them any symptoms and that this should be treated sooner rather than later. They also argue that since all women are supposed to have regular gynaecological check-ups and cervical smear tests, surely it is logical for them to ask about their own fertility. These arguments carry a great deal of force and there is no reason why a woman or even a couple should not seek advice regarding their fertility even before they plan to establish a pregnancy. This does not mean that extensive investigations should be undertaken, but a simple check-up to exclude any general disease, such as anaemia or any local condition within the reproductive tract, is certainly advisable. Any abnormality can then be treated or corrected rather than waiting for two years before its discovery.

When does Infertility Exist?

Infertility is something that is entirely relative depending as it does on age and circumstance. No one would pretend that a young woman of 18 who already has one child should seek advice about her inability to become pregnant again with the same urgency as a woman of 39 who married for the first time only six months previously. There are therefore two different aspects with regard to the advice that should be sought about fertility or infertility:

1. A routine general examination and examination of the pelvic organs to make certain that everything is normal.
2. Specialized examinations when a couple have failed to establish a pregnancy after a period of time which may vary from two years in the young to as little as three months in a woman who is older.

Investigation of Infertility

Medical History

The first and most important aspect in the consideration of fertility is the past medical history of both the woman and her husband. The woman’s past history will give many small indications about her fertility and normality. The age of onset of her periods, the regularity of her menstrual cycle, the duration and character of the flow, any pain and the time it occurs, evidence of ovulation pain or discomfort in the middle of the menstrual cycle, premenstrual tension, pain or other symptoms during the week or 10 days before the onset of the period, are all important. The doctor will ask about a past history of any generalized medical disease, especially those that might affect the liver, kidneys, heart or lungs, as well as any infection of the urinary tract (cystitis), or vaginal discharge; any abdominal operations, especially acute appendicitis, or any history of pelvic infection (especially gonorrhoea), previous pregnancy, miscarriage or abortion. The doctor will also want to know some details about sex life, especially the frequency of sexual intercourse and whether there is any pain or discomfort. The answers to all these simple questions, as well as to others concerning general health, are essential as a basis for a medical record.

A similar history is taken to obtain a record of the husband’s past and present medical health. Mumps is of particular importance, because it can affect the testicles.


The wife. A general examination confirms that the general health of the woman is satisfactory and pelvic examination excludes any local abnormality. Good general health improves fertility and some very simple advice such as reduction of weight, relief of anxiety, stress and strain, understanding of overtiredness and perhaps just simply a good holiday may go a long way towards correcting any latent or potential infertility that may exist.

The husband has a general physical examination which will discover any obvious abnormality. The commonest problem is overweight and a simple weight reducing diet should deal with it. Other factors such as overtiredness, overwork, anxiety, too much alcohol and too many cigarettes, while they may be considered of little significance, can in fact exert quite a marked effect on fertility. Examination of the genitalia excludes local abnormality.

Any obvious abnormalities that may be present in either the husband or the wife should be corrected. Advice will be given regarding the exact time of ovulation and the fact that pregnancy is most likely if intercourse takes place in the 2 or 3 days immediately preceding ovulation.

The doctor may refer the couple to an infertility clinic or to a specialist if a pregnancy is not established in what is considered a reasonable length of time.

Tests for the Husband

The most important test for the husband is an examination of the seminal fluid to ascertain the sperm count and other details about the semen. The specimen of seminal fluid must be obtained in a clean, sterile jar by a process of masturbation. Seminal fluid collected in a condom during intercourse is not satisfactory because the condom may contain chemicals that destroy or damage the sperms. Also it is of paramount importance that the entire ejaculate should be obtained. The specimen may be produced at home and taken to a laboratory, but care must be taken that the jar or bottle is kept at body temperature and it should arrive at the laboratory within an hour of ejaculation. The exact time of ejaculation should be noted on the bottle.

The investigations performed upon the seminal fluid and an example of normal results is:

Consistency: gelatinous
Colour: opaque, white
Volume: 2-5 ml.
Number of sperms: 60-150 million per ml.
Motility: 80 per cent motile after one hour.
Abnormal forms: less than 10 per cent
Pus cells: 0-1

It is obvious that the motility of the sperms as well as their normality is just as, if not more, important than the total number of sperms present. A reduction in the total number of sperms usually indicates that there is some suppression in the formation of sperms, the commonest reason for this being abnormal temperature regulation in the testicles. The testicles are meant to function at a temperature less than that of the body temperature and any factor or factors which tend to raise the temperature of the testicles will suppress or diminish the normal formation of an adequate number of sperms. Items such as jock-straps, close fitting underpants, repeated and prolonged hot baths, electric blankets and, especially, overweight, are all factors which tend to raise the temperature of the testicles and thus seriously diminish the manufacture of sperms. If any of these factors are applicable they should be eliminated. A cold bath twice daily or bathing the testicles in cold water twice daily helps to improve sperm formation. Over indulgence in alcohol or tobacco further diminishes the production of spermatozoa.

The other main group of sub-fertile men are those in whom the testicles produce an adequate number of sperms but infection or inflammation in the prostate and seminal vesicles results in inadequate storage and maintenance of the sperms and a rise in the number of pus cells present.

If there is any abnormality in the seminal count this is repeated on one or perhaps more occasions. If the abnormality persists, further investigation is undertaken in order to ascertain the cause of the deficiency before deciding on the necessary treatment.

Tests for the Wife

A very extensive and exhaustive series of tests has been designed for the infertile woman, but since these can only be undertaken in highly specialized gynaecological departments they have not been included here, especially as their value remains unproven.

Five main question are asked:

1. Is normal sexual intercourse occurring ?
2. Are the cervix and cervical canal healthy ?
3. Is normal ovulation occurring ?
4. Are the Fallopian tubes normal and functioning satisfactorily ?
5. Is the uterus normal and is the lining of the uterus properly prepared ?

Normal Sexual Intercourse

It is surprising how often sexual intercourse is, in fact, either unsatisfactory or occurring at the wrong time in the menstrual cycle or is so infrequent that the chances of conception are unlikely.

The Cervix and Cervical Canal

The mucus within the cervical canal is an essential part of the whole process of conception and if the cervix is infected or in any way abnormal, then the mucus within the canal may also be abnormal. The normality of the cervix together with the mucus are determined by simple clinical examination.

Post-coital test. This extremely simple test reveals a great deal of information. It is very probable that the mucus in the canal of the cervix will only permit the passage of spermatozoa at or about the time of ovulation and it is therefore important that this test should be undertaken at this particular time in the menstrual cycle.

Mucus from the canal of the cervix is very gently aspirated about 6 or 8 hours after intercourse and is then examined under the microscope. Under normal circumstances many active and normal spermatozoa will be present in the specimen. A complete absence of sperms in the specimen may mean an absence or reduced number of sperms in the seminal specimen, so that the husband must be retested. The presence of dead sperms in the cervical mucus even at the time of ovulation is a relatively common finding among women who are suffering from infertility and has given rise to the idea that some women will kill sperms in the cervical mucus. This apparent hostility of the cervical mucus to spermatozoa is inadequately understood but it may be the result of infection within the cervix and cervical canal, or of a very complicated immune reaction which is not yet completely understood.


Several methods can be used to find out if normal ovulation is taking place. Perhaps the simplest and the easiest is the daily recording of the basal body temperature. The temperature is taken each morning immediately on waking, which means that it must be taken before getting out of bed and also before having a drink. It is recorded on a special piece of graph paper provided for the purpose. The basal body temperature remains at a fairly constant level during menstruation and after menstruation until the 13th or 14th day of a regular 28-day cycle. The temperature may dip slightly when ovulation occurs and then immediately rise by anything from 0-5 to 1°F above the level of the temperature in the first half of the cycle. This temperature level is maintained until just before the next menstrual period when, if conception has not occurred, the temperature fells dramatically, followed by menstruation within 12 to 24 hours. The rise in basal body temperature is caused by the action of progesterone secreted from the corpus luteum during the second half of the menstrual cycle, so that if the body temperature does go up during the second half of the cycle, this is strong evidence that ovulation has occurred.

Proof of ovulation can also be obtained by examining the mucus from the canal of the cervix, the characteristics of which change at the time of ovulation.

The hormone progesterone affects the whole of the reproductive tract and the result of its activity on the vagina can be observed by taking vaginal smears during the first and second part of the menstrual cycle. If ovulation has occurred (and therefore progesterone is being produced), specific changes can be seen in the vaginal smears during the second half of the cycle.

Endometrial biopsy is a particular test in which a small portion of the lining of the inside of the uterus is removed during the second half of the menstrual cycle. This small operation is performed without any discomfort either in the out-patient department or as part of a more complicated and extensive investigation. If ovulation has occurred it is obvious from the lining of the uterus.

Ovulation should not only occur regularly, but must be associated with adequate production of the corpus luteum. Where ovulation fails or is inadequate, extensive testing may show a reason and may lead to the use of fertility drugs (such as clomiphene or gonadotrophins) which stimulate the ovary to produce mature follicles. In the more recently recognized condition of raised pituitary prolactin, bromocryptine allows natural ovulation (suppressed by prolactin) to occur and the corpus luteum to function properly. The investigation of ovulatory failure is a highly complex affair and should be conducted by a specialist unit. From such a unit fertility drugs may be prescribed but their effect will be closely observed.

Oral contraceptive pills. Fertility is not increased after a course of oral contraceptive tablets. There is no truth in the belief that a short course of oral contraceptive tablets results in a ‘fertility rebound’ during which fertility is increased. Even so, it is nevertheless true that pregnancy does occasionally follow a course of oral contraceptive tablets given to a woman who has previously proved to be infertile. The exact reason for this is not known, but it may have something to do with the reduction in emotion and tension which occurs when a woman is taking an oral contraceptive, knowing that pregnancy cannot occur. When she stops taking the pill she becomes pregnant before the tension has had time to build up again. Stopping the oral contraceptive tablets may also be carefully timed to coincide with a holiday which may therefore be the deciding factor together with an increase in the frequency of intercourse.

Tests of the Fallopian Tubes

If all the other tests have so far proved normal, then the state of the Fallopian tubes is assessed. If the Fallopian tubes are open they are said to be ‘patent’ and if they are not open they are said to be ‘blocked’. Tests of tubal potency are: insufflation, hysterosalpingography and laparoscopy. These three tests should be performed during the first half of the menstrual cycle as soon as possible after the end of the menstrual period.

Insufflation, which may be performed either as an out-patient or an in-patient, is a procedure for testing the Fallopian tubes by passing carbon dioxide through a special applicator into the uterus. If the Fallopian tubes are patent the gas will flow into the peritoneal cavity at a normal pressure. If the Fallopian tubes are blocked, then the carbon dioxide will not pass along them even if the pressure is raised to its highest permissible limit.

The information provided by a positive insufflation is that at least one Fallopian tube is functioning normally. It does not, however, give details of both Fallopian tubes, simply because the passage of gas along one tube will provide a normal tracing. If the carbon dioxide does not escape from the uterine cavity this does not necessarily mean that the tubes are, in fact, blocked. The muscular coat of the Fallopian tube may have gone into spasm which may be sufficient to prevent the passage of gas along the tube. Insufflation, therefore, does have certain limitations, although the case with which it can be performed and the lack of discomfort, as well as the fact that it does not require extensive equipment, combine to give it a useful place in the investigation of infertility.

Insufflation does have one further main advantage, in that occasionally the carbon dioxide may dislodge a mucous plug from the cavity of the Fallopian tubes. The frequency with which conception follows insufflation in a woman who has previously been considered infertile would indicate that this particular advantage occurs much more frequently than is generally appreciated.

Hysterosalpingography is an investigation similar to insufflation, except that X-ray opaque dye is injected into the uterus instead of gas. X-rays are taken which reveal details of the size of the cavity of the uterus, together with any possible congenital abnormality, or distortion of the cavity. They also provide information about the condition of the cervical canal, a factor that may be important in women who suffer from recurrent abortion. The shape, outline and position of the Fallopian tubes are demonstrated as the dye passes along them. As dye spills from the tubes into the abdominal cavity further information about the tubes and ovaries is obtained. This test is more reliable than insufflation particularly with new X-ray techniques and the use of the image intensifier.

Laparoscopy. This technique has become very popular for the investigation of infertility. Under general anaesthesia a half-inch incision is made in the umbilicus and the laparoscope (a narrow telescope-like instrument) is passed into the abdominal cavity. It contains its own light so that the surgeon can inspect the pelvic organs checking the uterus, tubes and ovaries for evidence of past or present disease. A blue harmless dye introduced into the uterus through the cervix will be seen to spill out into the pelvis cavity if the tubes are patent. Laparoscopy will enable the surgeon to decide if surgery to the tubes is necessary to help restore fertility.

Artificial Insemination

Artificial insemination is used to describe the technique whereby seminal fluid, previously produced, is placed at the top of the vagina or in the canal of the cervix. The seminal specimen may be produced by the husband, in which case it is known as ‘artificial insemination husband’ (A.I.H.) or by a donor especially selected for that purpose, in which case it is known as ‘artificial insemination donor’ (A.I.D.). There are many ethical and legal arguments surrounding both A.I.H. and A.I.D. Obviously artificial insemination by a donor is a much more drastic step than artificial insemination by the husband, but artificial insemination in any circumstances should not be undertaken without very careful consideration and discussion of all the available facts with the family doctor. Before artificial insemination can be considered, the wife must be very carefully examined to ensure that she is capable of having a normal pregnancy and a normal baby and also to ascertain accurately the time of ovulation.

Artificial insemination by a husband is only performed where normal intercourse is either not possible or not practicable, or where a specialist might consider that the amount of seminal fluid is so small that there is an advantage to be gained by artificial insemination. A.I.H. can be performed by the woman herself by the use of a special cervical applicator, in which the seminal fluid is placed and which she then puts in the vagina and over the cervix. In this way there is a maximum possibility of the sperms entering the cervical canal.

Donor insemination is usually restricted to those instances where it has been conclusively proved that the husband has no sperms or that his sperm count is so low as to render pregnancy either very unlikely or actually impossible. Artificial insemination by donor is not normally available as part of the National Health Service. A donor is very carefully selected because his height, colouring, physique and intelligence are similar to the husband’s, and his seminal count is tested. If it is found to be normal, artificial insemination with a specimen of the donor’s seminal fluid is performed by the doctor, who places the semen at the top of the vagina close to the cervix by means of a special syringe and cannula. It is obvious that the donor and the recipient should not meet, nor be aware of each other’s identity.

Some couples seek artificial insemination donor as an alternative to adoption. Since the introduction of the abortion act the number of babies available for adoption has been drastically reduced and it is, therefore, possible that the demand for artificial insemination donor may increase in the future.

Rhesus incompatibility. Some women became sensitized before anti-D immunoglobulin was available and have suffered from several disastrous and unproductive pregnancies as a result of Rhesus incompatibility. If such a woman is married to a homozygous Rhesus positive husband the couple may have considered the possibility of artificial insemination with a Rhesus negative donor. Such artificial insemination would give rise to a Rhesus negative baby who would not be affected by the mother’s antibody.