Why recurrent miscarriages
may actually be caused by 'super-fertility'
Embryos that would not usually survive early pregnancy may last long enough to give a positive test
11:14 GMT, 24 August 2012
Women who suffer recurrent miscarriages may actually be 'super-fertile', experts have claimed.
The problem – which affects around one in 100 women – occurs because their bodies are in fact too good at letting embryos implant in the uterus, they say.
Embryos that would not normally survive the earliest stages of pregnancy, in some women may last long enough to give a positive pregnancy test, a study led by Professor Nick Macklon, a consultant in obstetrics and gynaecology at the Princess Anne Hospital in Southampton, found.
False hope: Some embryos may last long enough to give a positive pregnancy test – even though they will not survive longer
Prof Macklon, who is also director of the Complete Fertility Centre Southampton, said: 'In half of women who have recurrent miscarriages, we don't know what the cause is, and many affected women feel guilty that they are simply rejecting their pregnancy.
'But we have discovered it may not be because they cannot carry; it is because they may simply be super-fertile, as they allow embryos which would normally not survive to implant.'
Prof Macklon, working with colleagues at University Medical Centre Utrecht in the Netherlands, compared cells from the lining of the wombs of women who have suffered recurrent miscarriage and those with normal fertility cycles.
They found cells from those with recurrent miscarriage move towards embryos, encouraging implantation regardless of quality, but those from normally fertile women were selective.
Prof Macklon explained: 'Only around 30 per cent of every 100 natural conceptions makes it to a baby and the rest are lost early in pregnancy. Mercifully, most women remain unaware of these losses because they happen before they miss their period.
Findings: The research was carried out at Princess Anne Hospital in Southampton
'When poorer embryos are allowed to implant, they may last long enough in cases of recurrent miscarriage to give a positive pregnancy test.'
Prof Macklon, who is chair of obstetrics and gynaecology at the University of Southampton, said the research, published in journal PLoS ONE, was a significant moment for sufferers.
He said: 'For the first time, women who have suffered with this extremely difficult problem can take some comfort by having a clearer understanding of the causes and realising they are not bad at carrying but perhaps too good.
'With much better understanding of how the female body selects – or doesn't select – embryos, we hope to now explore ways we can fix this.'