Subfertility is defined as a failure to become pregnant for more than twelve months, despite focused attempts to conceive. The terms ‘subfertility’ and ‘infertility’ are sometimes used interchangeably and mean the same thing. However, in Dutch, the term ‘infertility’ (infertiliteit) can be interpreted negatively as it can also mean permanent infertility. Subfertility is a common condition affecting couples, with important psychological, economic, demographic and medical implications.
Several conditions can cause subfertility, but, in about 30% of the couples who have problems getting pregnant, the cause remains unexplained. Known causes are ovulation disorders (24%), reduced sperm quality (20%), disturbance in the interaction of semen and cervical mucus (15%) and tuba pathology (11%, e.g. due to severe endometriosis). Both male and female factors may contribute. Increasing female age is a major factor associated with subfertility. (Female) cases of being overweight and obesity are related to reduced fertility. Cigarette smoking and alcohol consumption may decrease the rate of successful conception.
When a pair presents with subfertility, the GP will take a thorough history from both and, on indication, perform a physical examination, focused on ovulation disorders and tuba pathology. The pair’s knowledge on the fertile period and possible sexual problems should be assessed. This is also relevant when periods of less than twelve months of failure to conceive have passed. Subfertility may be associated with emotional problems and may have an impact on relationships and work. When the diagnosis of subfertility is made, semen analysis and a female chlamydia antibody titres assessment may be performed.
Depending on the findings, a referral to the gynaecologist is suggested to discuss possibilities for treatment. If all findings are normal, it depends on the chances of spontaneous pregnancy and the couple’s preference whether waiting or referral to the gynaecologist is most appropriate. Prognostic models are available to estimate the chance of pregnancy, including the woman’s age, the presence or absence of a previous pregnancy and the results of the sperm investigation.
In ICPC-2, ‘infertility / subfertility female’ is coded W15. ‘Infertility / subfertility male’ is coded Y10. Both are symptom diagnoses: they classify the symptom (failure to become pregnant) and not an underlying cause. If additional investigation results in a classifying disease / disorder, the new diagnosis will be recorded. This may replace the symptom diagnosis ‘subfertility’, but it may also be added to it, especially if treatment is primarily focused on the subfertility and not on the underlying disease.
Additional diagnoses besides ‘infertility / subfertility’ may also be other symptom diagnoses, for example, menstrual cycle disorders. Irregular menstruation (X07) or oligomenorrhoea / amenorrhoea (scanty or absent menstruation, X05) can be added if they lead to specific advice or other interventions for this. If patients or couples present with questions or complaints regarding fertility, but the GP does not classify this health problem as ‘subfertility’ (W15 / Y10), FaMe-Net GPs can use the ICPC-2 code A98 (‘Prevention’) and use the ICD-10 subclass ‘advice regarding reproduction’.
Female subfertility (W15) has an incidence of 3.8 per 1000 patient years, meaning almost four new diagnoses of female subfertility in a year in a practice with 1000 female patients. Link/Figure 1
Male subfertility (Y10) has an incidence of 2.8 per 1000 patient years, meaning almost three new diagnoses of male subfertility in a year in a practice with 1000 male patients. Link/Figure 2
The prevalence of ‘subfertility female’ (W15) is 8.1 per 1000 female patient years, meaning that among 1000 female patients in a year, eight receive help or guidance from their GP for subfertility. Link/Figure 3
The prevalence of ‘subfertility male’ (Y10) is 3.9 per 1000 male patient years, meaning that among 1000 male patients in a year, four receive help or guidance from their GP for subfertility. Link/Figure 4
Subfertility is usually a problem for a couple, but is recorded more commonly among female patients in the FaMe-Net database than among males. In this website, data cannot be studied in residential association (i.e. for couples). This would be possible with additional data extractions (on request). The data implies, however, that subfertility as a health problem is sometimes presented to the GP by a couple but sometimes by a woman alone.
The incidence and prevalence are highest in the age group 25-44 years, both among women and men. In this age group, 26 per 1000 female patients present to their GP with subfertility throughout the year (prevalence). Subfertility is also prevalent in the age group 15-24 years, especially among women (1.3 per 1000 patient years). In the age group 45-64 years, a new or existing diagnosis of subfertility is rare, but occurs more often in men (incidence 0.6, prevalence 0.9 per 1000 patient years) compared to women (incidence 0.3, prevalence 0.6 per 1000 patient years).
Among women aged 25-44, subfertility is ranked 34 in the ‘Top Prevalence’ list of conditions affecting a large proportion of the population and presented to the GP. ‘Pregnancy’ (W78) is the number one prevalent condition in this group, followed by two other reproduction related conditions (oral contraception (W11) and intrauterine contraception (W12)). Link/Table 5
‘Subfertility’ (W15 and Y10) is a symptom diagnosis and thus also the most common reason for encounter (RFE). Other frequent RFEs are a request for a referral to the hospital (*67), a request for advice (*45) or the need for ‘reproductional advice’ (A98). In women, subfertility is sometimes initially presented with the RFE irregular menstruation (X07). Link/Table 6 Men sometimes present with the request for a sperm investigation (*38) or being sent by someone else (*65). Link/Table 7
A referral to secondary care is made in 50% of episodes of subfertility among women (W15, Link/Table 8) and in 60% among men (Y10, Link/Table 9). This concerns the percentage of referrals made per episode per calendar year. These referrals are directed to the gynaecologist and, in men, occasionally to the urologist. Link/Table 10, Link/Table 11 Other common interventions are health education / advice, lab tests, and in men (Y10), sperm investigation (in 36%). Medication prescriptions for subfertility (W15) occur only seldomly by the GP. Link/Table 12
Dutch guideline: https://richtlijnen.nhg.org/standaarden/subfertiliteit#volledige-tekst (2010)
Hornstein MD, Gibbons WE, Schenken RS. Natural fertility and impact of lifestyle factors. In: UpToDate, Barbieri RL, Eckler K (Eds), UpToDate, Waltham, MA, 2021
