If you’re trying to get pregnant, or even planning to try to get pregnant, you might make the assumption that being ‘super-fertile’ is a good thing. It suggests that having lots of babies comes naturally, right?
Sadly it's not quite that simple. Super-fertility (or 'hyperfertility' as you may also see it referred to) is a term that has been given to describe a theoretical condition where a person's endometrium is super-receptive and so allows many more embryos to implant, irrespective of their quality. As a result, the likelihood of a positive pregnancy test showing up for someone who is super-fertile is higher than average.
Human reproduction is, according to a fertility expert at the Royal College of Obstetricians and Gynaecologists (RCOG) in the UK, not hugely efficient. In fact, at peak fertility, only about 25% of couples conceive each month of trying, and about 85% conceive after a whole year. However, for so-called super-fertile people, the womb lining (or endometrium) cannot discern between 'good' and 'bad' quality embryos. As a result, it lets embryos that may not be 'genetically normal' and should be rejected implant themselves anyway. This unfortunately leads to a greater-than-average number of pregnancies that might be destined to miscarry, the RCOG tells R29.
Consequently, being super-fertile would not necessarily mean a higher possibility of having children. However, it is a possible cause of recurrent miscarriages (defined as the loss of three or more consecutive pregnancies). While we don't know the prevalence of super-fertility, we do know that recurrent miscarriages affect around 5% of couples in Australia.
The idea of super-fertility is a very new area of research and was first identified by a study done in 2012. The UK-Dutch study, done at the Princess Anne Hospital in Southampton and the University Medical Center Utrecht, tested the womb cells of six women who had 'normal' fertility and six who had experienced recurrent miscarriages. It was found that while the cells of the fertile women ignored the low-quality embryos and only reached out to the high-quality ones, the cells of the women with recurrent miscarriages reached out to all kinds of embryos.
As Professor Nick Macklon from Princess Anne Hospital explained to the BBC at the time, "Many affected women feel guilty that they are simply rejecting their pregnancy. But we have discovered it may not be because they cannot carry, [but] it is because they may simply be super-fertile, as they allow embryos which would normally not survive to implant."
This theory does not explain all miscarriages and Professor Siobhan Quenby from the RCOG warned that more research is needed to explore whether super-fertility can be tested for in women and therefore their receptiveness to embryos altered. However, there have been no further studies in the area published as yet.
It's worth mentioning that colloquially, the phrase 'hyperfertility' has taken on another definition, one resting on stereotypes around people from certain backgrounds (like Catholic or South Asian backgrounds), and carries negative connotations of its own. For example, as behavioural scientist and writer Dr Pragya Agarwal noted in a piece for The Independent, the fact that women of colour are often presumed to be 'hyperfertile' and even "contributors to rapid population growth and crowding in inner city areas" means that for those women of colour struggling with issues of infertility, help is not forthcoming. Reckoning with one's problems conceiving or carrying a pregnancy to term when it is assumed that because of your background or culture that you can and will have many children brings with it guilt and shame. But not only are those stereotypes of being especially fertile damaging for the women in those communities, they also distract from how devastating potential 'super-fertility', and in turn, recurrent miscarriages, can be.
As mentioned, much more work needs to be done in this area. Professor Siobhan Quenby for leads the implantation research clinic at University Hospital Coventry & Warwickshire and sees up to 500 new patients a year to help women who suffer from recurrent miscarriages and infertility to conceive and give birth to healthy babies. You can find out more about her work over at the Warwick Medical School website.
For anyone that's worried about their own fertility, they are advised to contact their GP and request an appointment with a specialist.