Traditionally, infertility has been defined as “the inability of couples to achieve conception after a year of unprotected intercourse, or the inability to carry a pregnancy to term.”
To women and couples who are having problems conceiving, it can feel like failure, and seem that they're alone in experiencing these difficulties in getting pregnant. But the reality is that this happens much more often than people realise. At some point in their lives, at least 1 in 6 couples will experience some degree of infertility.
The cause of infertility is not always apparent. In many cases, both partners can appear to be fine, but still there's no pregnancy. This is known as unexplained infertility.
If someone has an obvious, serious reproductive condition, it is easier to identify and treat the probable cause of the infertility. On the other hand, minor disruptions, which might not be the only cause of the infertility, are often the most difficult to treat.
Degrees of fertility
Infertility can be 'complete' (also called 'sterility'), which means you absolutely cannot get pregnant without help. Or it can be 'incomplete', also called 'subfertility', which means that there is no absolute barrier but the odds are reduced compared with normal and getting pregnant will take more time - sometimes too much time.
There are just four factors that can stop a woman getting pregnant:
- No sperm
- No eggs
- A problem that prevents sperm coming in contact with eggs
- A problem with implantation of the embryo in the uterus
Each of these factors can have a number of different causes and the challenge for your fertility specialist is to determine which of them are responsible for your infertility.
If a single major cause is found, e.g. a blockage of the fallopian tubes, treatment may be simple - an operation that successfully removes the blockage should return the patient to full fertility allowing her to get pregnant naturally. Problems occur when an obvious cause cannot be found or when too many minor causes are found.
A normal fertile couple in their 20s having regular sex would have a monthly chance of pregnancy of about 20%. Pregnancy would be expected within 4-6 months of trying. When a year has passed without successful conception the monthly chance of pregnancy will be much lower than this, and so you should consider seeking help at about this stage. There needn't be a major reproductive condition to affect fertility levels. Even minor disturbances, especially in combinations, can cause the monthly chance of pregnancy to be much reduced.
To illustrate the effect of multiple, minor factors in infertility, a model can be constructed to estimate the chance of pregnancy per month and the amount of time it will on average take to get pregnant:
|Number of mild factors||Monthly chance of pregnancy||Estimated time to a pregnancy|
It is easy to see that it doesn't take much to reduce the chance of pregnancy quite significantly. Perhaps a slightly low sperm count and mild endometriosis? Even with two mild cases of such common conditions, the expected time to conception could be up to 7 years.
In these cases, recourse to treatments such as IVF is often seen as the best way to achieve a pregnancy. IVF places sperm in direct contact with eggs and returns embryos to the optimal position in the uterus, circumventing most of the myriad causes of infertility.
If you've been trying to get pregnant for 12 months (or 6 months for women over the age of 35) assisted conception might be needed.