What are the most common causes of infertility?

There are several mandatory preconditions for fertility:

The causes of infertility and their approximate frequency are given in Table 7.1.

TABLE 7.1 Causes of infertility and their approximate frequency

* Total exceeds 100%, as 15% of couples have more than one cause of subfertility.

(From Hull et al¹⁶)

Sperm dysfunction is the most common cause of infertility, accounting for 30% of cases. Problems are often detected in motility, morphology and ability to penetrate mucus. Complete absence of sperm is rare.

The next most common problem is related to ovulatory failure, with women experiencing either amenorrhoea or oligomenorrhoea. The latter condition is most commonly due to polycystic ovary syndrome (PCOS). Fallopian tube blockage or damage is most commonly due to a past history of Chlamydia infection that may or may not have been detected earlier on.

Other factors that may be playing a significant role in a couple’s subfertility include:

The longer the duration of infertility, the less likely it is that a couple will fall pregnant, especially if it is longer than 3 years.³ Equally, a previous full-term pregnancy is associated with a better chance of conception.³ In 25% of cases, no definite cause of infertility is found.¹

When should a GP commence investigation in a couple claiming to be infertile?

The answer to this question is dependent on many factors, the most important of which is probably the woman’s age.

If a couple in their 20s present earlier than 6 months after trying to conceive, it is reasonable to offer some general fertility advice and preconception care. This might include asking about the regularity of the menstrual cycle and the frequency of intercourse in relation to peak time of fertility in the menstrual cycle, as well as counselling about weight and smoking. If they are still not successful after a year, the couple can then return for a more thorough history and examination.

It is important to be aware that once a couple presents to a doctor with subfertility, they are getting on to a ‘treadmill’ that it is difficult to leave. They have to deal with the fact that either the man or the woman may be infertile or that there is no explanation for their infertility. They may feel guilty or blame their partner for causing the problem. Sexual relations become pressured because of the need to have intercourse ‘at the right time’, and women build up their expectations of conceiving, often to be disappointed by finding that they are menstruating again. They will often describe being on an ‘emotional rollercoaster’. Hence some recommend that in a younger couple medical involvement in this intimate area should be delayed for as long as possible.

In older couples, with regular unprotected sexual intercourse, 94% of fertile women aged 35 years, and 77% of those aged 38 years, will conceive after 3 years of trying,⁴ demonstrating the decline in female fertility with age (the effect of age on male fertility is less clear). Because of this decline, guidelines recommend earlier investigation. This is also because the success of assisted conception techniques is also highly related to maternal age (Table 7.2). In particular if the woman is over 35 there is a substantial fall in the chance of success with in vitro fertilisation.⁵

TABLE 7.2 Chance of live birth per treatment cycle

(From NICE Guidelines⁶)

GPs should be aware that many patients will present with difficulties in falling pregnant, having not received any preconception care. It is therefore imperative GPs take the opportunity to go through the checklist of preconception care advice (see Chapter 8) with patients and ensure that the woman has adequate knowledge to identify her peak fertile time, has immunity against rubella and varicella, and is taking the appropriate dose of folate.

Are there any tests that patients can perform at home?

Home-based tests can be useful in several situations. First, they are appropriate for those couples who are concerned about fertility (before attempting to conceive for 1 year) and who do not warrant immediate investigation. Another group are those who are undergoing medical investigation, who may welcome involvement in the process and who might feel empowered by gathering information about their own cycle. Patients should not undertake these tests indefinitely because of the stress they may generate. Three months is probably sufficient time to gather the maximum amount of information that can be garnered from such tests. The two tests that are available to women who are concerned about their fertility are tests that involve charting their basal body temperature and using an ovulation predictor kit.

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