Why does this happen?

Infertility is often thought of as an absolute condition – people can either conceive or they are infertile. But those of us practising in the field for very many years understand that successful conception requires a myriad of amazing interactions both in the male as well as the female reproductive system.

For very many couples being fertile or infertile (some like to use the work ‘subfertile’) it is more about the efficiency of the reproductive processes than any absolute infertile (sterile) condition. What is an absolute infertile condition? If a woman has blocked Fallopian tubes, if a man has very few sperm, or does not manufacture any, then this couple can only have a baby by IVF technology.

However, some IVF clinics today may see as many couples requiring IVF for an ‘inefficiency issue’ as they do for an absolute infertility condition. For example, if a man has a low sperm count, or the majority of his sperm are not fertile, then it may be possible he can still have a child naturally, but it may just take a lot longer to do so. If he has this condition and just by good fortune they conceived early, the first time they try perhaps, then they would not know this condition existed; even though it may be as severe as in couples who take years then end up in an IVF clinic. Indeed, IVF clinics see many patients with the reverse situation – they have been trying for years, they succeed with IVF, then go on to have several more children naturally.

So, if we imagine the female reproductive system, involving glands in the brain, other involved specialised glands around the body, the ovary, the Fallopian tubes, the uterus and the lining of the uterus for the site of implantation; the innumerable interactions of hormones, tissue responses, ovulatory process, transport systems, to name just a few, we can see why a problem in any one of the areas may create some inefficiencies, rather than absolute infertility. And that is just the female! The male equally has many systems in his reproductive process, including the 70 days to manufacture a sperm.

Unlike females, who are born with their eggs, men are only born with ‘precursor cells’ – these cells start manufacturing sperm at puberty and continue throughout a man’s life. That’s why for some men a virus, for example, can cause bad sperm counts for several months, but these then get back to normal as the ‘manufacturing process’ picks up. Equally, a virus infection such as mumps at a young age, or an injury to the testes can delete sperm production permanently. Even when the man makes sperm, and a normal number of them, they may still be unable to fertilise an egg because of some underlying ‘subcellular’ errors in the sperm itself. Similarly, an egg may not fertilise because it has subcellular problems. When and egg and sperm combine to allow fertilisation it has to be perfect, like a lock and key mechanism – sometimes the lock or the key do not function properly.  Many couples, even after having their first baby, are told they have ‘unexplained secondary infertility’:  clearly there is a reason it just remains unknown to available tests, despite the multitude of tests we now have to try to pinpoint the problem. Most of these couples today can succeed with IVF even if the underlying cause still remains unexplained.

Last, but not least, very many couples have slight inefficiencies on both sides – in the male and female partners. This will compound the problem. One aspect that is often overlooked, especially in secondary infertility, is female age. If the couple are experiencing ‘secondary infertility’, they are often told just to keep trying – but if the female is in her late 30’s, then there is a real risk that whatever the underlying issue, the fact that she is progressing to becoming ‘reproductively older’ may start to become much more of an issue than the original underlying condition. We know as women get into their late 30’s the eggs carry more genetic problems, the majority are not viable, but those that are fertilised and make an embryo have a much higher chance of miscarriage, or not even implanting than eggs from younger women.