Clinical course of subfertility

Subfertility is defined as a failure to become pregnant for more than twelve months, despite focused attempts to conceive. Sometimes, the terms ‘subfertility’ and ‘infertility’ are used interchangeably. Subfertility is a common condition affecting couples, with important psychologic, economic, demographic, and medical implications. 

Different conditions may cause subfertility, although in roughly 30% of the couples facing problems to conceive the cause remains unexplained. Known causes are ovulation disorders (20-25%), reduced sperm quality (20%), disturbance in the interaction of semen and cervical mucus (15%), and tuba pathology (e.g. from severe endometriosis). Both male and female factors may contribute. Increasing female age is a main factor associated with subfertility. (Female) 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 and, on indication, 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 shorter periods than twelve months of failure to conceive have passed. Subfertility may be associated with emotional problems and may have an impact on relation and work. 

When the diagnosis subfertility is made, semen analysis and 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, presence or absence of a previous pregnancy, and results of the sperm investigation. 

How is subfertility recorded in FaMe-Net?

In ICPC-2, ‘infertility/subfertility female’ is coded with W15. ‘Infertility/subfertility male’ is coded with 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. 

If patients or couples present with questions or complaints regarding fertility, but the GP does not classify this health issue with a diagnosis of subfertility, FaMe-Net GPs will code code A98 ‘Prevention’ and use the ICD-10 subclass labelled ‘advice regarding reproduction’. 

Additionally, menstrual cycle disorders may be coded when present and when specific advice and/or action is provided for this symptom, for example irregular menstruation (X07) or oligomenorrhoea / amenorrhoea (scanty or absent menstruation) which is coded with X05. 

Epidemiology of subfertility in FaMe-Net

Subfertility female (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  Subfertility male (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, almost four receive help or guidance help from their GP for subfertility. Link/Figure 4   

Subfertility is a problem for a couple but it 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. within couples). This would be possible with additional data extractions (on request). The data imply however that subfertility is sometimes presented to the GP by a couple but sometimes by a woman alone. Obviously, W15 ‘subfertility female’ is recorded only among women and Y10 ‘subfertility male’ only in men. 

Logically, 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. Subfertility is also recorded in the age group 15-24 years. In the age group 45-64 years, a new diagnosis of subfertility is rare, but occurs twice more often in men compared to women. 

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  (contraception oral / intrauterine). Link/Table 5

How do patients with subfertility present?

 ‘Subfertility’ (W15 and Y10) is a symptom diagnosis and therefore it is logical that this is also the most common reason for encounter (RFE). Other frequent RFEs are a request for a referral (*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). Men sometimes present with the request for a sperm investigation (*38) or initiated by someone else (*65). Link/Table 6, Link/Table 7

How do FaMe-Net GPs act

A referral to secondary care was made in 50% of episodes of subfertility among women (W15) and in 60% among men (Y10). This concerns the percentage of referrals made per episode per calendar year. Link/Table 8, Link/Table 9 These referrals were directed to the gynaecologist and in men occasionally to the urologist. Link/Table 10, Link/Table 11 Other common interventions were health education/advice, lab tests, and in men (Y10) sperm investigation (in 36%). Medication prescriptions for subfertility (W15) occurred only seldomly by the GP. Link/Table 12

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