Around 23 million miscarriages occur annually worldwide. While some countries and organisations may define the time-scale differently, according to the HSE, miscarriage is the loss of pregnancy before 24 weeks.
While sporadic miscarriage is common, affecting some 10–20 per cent of pregnancies, recurrent miscarriage – defined as three consecutive first-trimester miscarriages – is much less common, affecting 1–2 per cent of pregnancies. Risk factors for recurrent miscarriage include a maternal age younger than 20 years, or over 35; black ethnicity; smoking; paternal age over 40; previous miscarriages; air pollution; and body-mass index of less than 18.5 kg/m2 or more than 30 kg/m2 (BMI is a simple calculation using a person’s height and weight – where kg is a person’s weight and m2 is their height in metres squared).
However, encouraging results have been reported following a major Irish study of all patients who attended a recurrent miscarriage clinic from January 2014 to January 2021. Writing in the Irish Journal of Medical Science, researchers from Dublin’s National Maternity Hospital and Merrion Fertility Clinic concluded: “Patients who attend a dedicated recurrent miscarriage clinic for investigation and treatment have a high live birth rate in a subsequent pregnancy. A subsequent pregnancy following recurrent pregnancy loss does not appear to be associated with an increased risk of adverse pregnancy outcomes.”
Over the study period, of 488 patients referred to the recurrent miscarriage clinic after three consecutive miscarriages, 318 had a further pregnancy and the subsequent live birth rate was 75.3 per cent, with 22 per cent having a further pregnancy loss. The live birth rate aligned with the results of a multi-centre trial which found that 65.8 per cent of women with recurrent miscarriage would ultimately have a live birth.
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What prompted the study? Lead author Dr Niamh Fee is a specialist registrar in obstetrics and gynaecology. She says the specialist recurrent miscarriage clinic at the National Maternity Hospital investigates and manages patients following recurrent pregnancy loss: “Recurrent pregnancy loss,” says Dr Fee, “can result in significant physical and psychological distress. Therefore, the objective of this work was to evaluate our own outcomes for our patients who had attended this clinic so that we could provide up-to-date information for our current and future patients.”
Why do miscarriages occur? “The commonest cause of pregnancy loss is aneuploidy,” says senior author Dr David Crosby, a consultant obstetrician and gynaecologist and head of reproductive medicine at the National Maternity Hospital. “Aneuploidy occurs when the egg and sperm meet, and an extra copy of a chromosome is passed from either parent to their offspring, and of the patients in our study who had this testing performed, we found aneuploidy was the cause in almost three-quarters of pregnancy losses.”
Although aneuploidy is the commonest cause of a pregnancy loss, says Dr Fee, “it often occurs completely by chance and is unlikely to recur resulting in recurrent miscarriage, except in certain circumstances”.
The results of this study, the report says, “provide useful information which can be used for informing patients about the pregnancy outcome of patients who have attended this recurrent miscarriage clinic”, and Dr Crosby says their findings “can give our current and future patients up to date information and reassuring data from our own centre, which can assist with future pregnancy planning”.
As far as future studies are concerned, Dr Fee is clear “that research continues into recurrent pregnancy loss, as a number of patients may never have a cause found despite full investigation. If further causes are established for these patients, it may result in effective evidence-based treatment options for patients in the future.”
Dr Fee and Dr Crosby say the high proportion of patients with recurrent pregnancy loss who attended their recurrent miscarriage clinic, and who, as Dr Fee says, “after appropriate investigation and management, had an uncomplicated pregnancy and birth in a future pregnancy with supportive therapy through the National Maternity Hospital’s specialised Tender Loving Care antenatal service”.
[ Men are often ‘the forgotten mourners’ of miscarriageOpens in new window ]
Society and medicine’s views of miscarriage appear to be changing. In May 2021 an editorial in the medical journal The Lancet observed that “the insidious implication that miscarriage, like other women’s reproductive health issues, including menstrual pain and menopause, should be managed with minimal medical intervention is ideological, not evidence-based... The era of telling women to ‘just try again’ is over.” Such a retrograde mindset states the editorial, “underestimates, and risks dismissing, the personal physical and mental consequences of a miscarriage. It has also affected the availability and quality of care that women receive after a miscarriage and does not accurately reflect the evidence on management.”
In this context the work of Dr Fee and colleagues is timely in adding to the evidence base that addresses the challenge of recurrent miscarriage through a recurrent miscarriage clinic. Last year, University College Cork (UCC) researchers reported the results of a survey into the care experiences of men and women who had received recurrent miscarriage care in the Republic of Ireland. They found that of 135 women questioned, 24 per cent rated a poor experience of recurrent miscarriage care and the researchers further identified areas for improvements “such as communication and better care coordination between healthcare professionals across hospitals/units”.
However, Dr Fee says the National Women and Infants Health Programme has recently published a new guideline for the management and investigation of recurrent miscarriage in Ireland. “The guideline was developed by the UCC group and should promote improved care for women who experience recurrent miscarriage.”
This, together with the findings of the consultant-led antenatal recurrent miscarriage clinic as described by Dr Fee and colleagues, should help to illuminate a way forward through an evolving reproductive landscape.