Multiple births - their risks and how to prevent them

July 01, 2002

Vienna, Austria: The continuing high rate of multiple pregnancies in assisted reproduction is a major medical, psychosocial and economic problem. But it could be solved overnight if only doctors weren't too hesitant to act, a leading Swedish specialist in reproductive medicine told a news briefing today (Monday 1 July) at the annual meeting of the European Society of Human Reproduction and Embryology in Vienna.

Dr Karl Nygren, Associate Professor of Obstetrics and Gynaecology at Sofiahemmet Hospital in Stockholm, said that the natural rate of multiple births was around one percent but was between 20% and 40% for women who used assisted reproductive techniques - either ovarian stimulation or IVF, or a combination.

"The reason for multiple pregnancies is the drive to maximise effectiveness. More embryos per transfer means higher efficacy and a shorter period of time to achieving births. However, evidence is accumulating that a policy leading to multiple births means increased risk of prematurity and, consequently higher mortality, disability and ill health. There are also psychosocial problems - more difficult pregnancies, more caesarean sections, prolonged breast feeding and extra stress, particularly for the mother and especially during the early years of childhood. The economic consequences can be overwhelming as well."

Dr Nygren said that the push for multiple pregnancies was driven by a combination of factors - • costs - more babies in one go gets round the problem of lack of resources hindering further attempts, while the high costs of treating premature babies resulting from multiple pregnancies are usually met from different sources than those financing reproductive treatment • patients' wishes - they want to meet their reproductive goals as quickly as possible • ompetition among doctors - a reputation for excellence and success attracts resources - efficacy is often reported without due observation of the multiple pregnancy rates and other problems

But times were changing, said Dr Nygren. "Doctors and patients are beginning to realise that the incidence of multiple pregnancy must be reduced. To maintain efficacy we need to make a better selection of viable embryos and to identify patients at highest risk for multiple pregnancy."

Foetal reduction in early pregnancy - a practice which was rare in some countries but quite frequent in others - was not the answer, he warned. "It's a blind alley. It should not, in the future, be part of the treatment package. It's ethically very difficult to accept and has grave psychological side effects for patients and the staff who treat them.

"The problem of multiple pregnancies could be solved overnight if we doctors had the will. Although multiple pregnancies are driven by a number of factors they are essentially iatrogenic - caused by doctors. If we only transferred one embryo to the uterus during IVF and if we always meticulously monitored ovarian stimulation to ensure that only one follicle ovulates, the problem would disappear.

"The solution is there, but we hesitate to implement it. The medical profession should aim at a plan for self-regulation. Otherwise we could face legal action, which would be much more difficult to handle in practice."

Dr Nygren concluded that even without an overnight solution the problem should eventually be solved. "More research and the distribution of the results may lead to an awareness from doctors that self-regulation is necessary and to a shift in public opinion, fuelling demands to change current clinical practice."

French fertility experts find multiple pregnancies pose major risks to babies' lives and health

French fertility experts* have carried out an analysis of nearly 25,000 pregnancies that has clearly demonstrated that babies who are part of a multiple pregnancy face major risks to their life and health.

They studied 24,989 pregnancies resulting in 32,389 babies born using reproductive technologies in France between 1986 and 1998. Main health markers - gestational age, weight and mortality - were compared for single babies (18,235), twins (11,905) and triplets (1,772).

Lead investigator Professor Emile Papiernik from Hôpital Port Royal in Paris, said that prematurity (under 37 weeks gestation) was strongly related to multiple pregnancy, with nearly 87% of triplets and over 42% of twins being premature compared with just over 8% of single babies. More than 5% of babies were born before 33 weeks of pregnancy with over 28% of these very premature babies being triplets, nearly 8% being twins and less than 2% being singletons.

Over 57% of the babies who were small for their gestational age were triplets, nearly 43% were twins and just over 17% were singletons.

Deaths in the period around birth were five times as frequent for triplets as for single babies (a rate of nearly 40 per 1,000 compared with under 8 per 1,000 for single babies). For twins it was just over 20 per 1,000. "In total, twins and triplets represented 43% of the newborns, but 80% of the extreme preterm babies (born earlier than 28 weeks of pregnancy), 82% of the very preterm (under 33 weeks) and 81% of the total preterm births. They accounted for two thirds of the 'small for dates' babies and 70% of the perinatal deaths."

Professor Papiernik concluded: "Multiple pregnancy is a very important risk factor for the babies' health, particularly in assisted reproduction where it represents over 40% of the newborns but 70% to 80% of the pathologies. Although it has decreased in most of the European countries it remains at an unsatisfactory level."

NB: Professor Papiernik's colleague on the research team, Dr Jacques de Mouzon, from INSERM, will give this presentation to the conference.

* The research team involved experts from Hôpital Port Royal, Paris, INSERM in Bicêtre and the FIVNAT centres. Association FIVNAT was created in 1986 in France in order to evaluate IVF practice and results in France. It was one of the first and most significant epidemiological registers of IVF in the world and is a world reference for those working in reproductive medicine

Abstract no: O-014 (Monday 11.15hrs CET Hall D) URL:

Multiple births are falling but remain a public health challenge, says French researcher

Another study using data from 200,000 births recorded in the FIVNAT register found that the proportion of multiple births fell in France in the 1990s - but only from 55.6% to 41% in 1999.

During the period from 1987 to 1990 there was an increase in the numbers of embryos being transferred and more than 28% of deliveries were twin births and 8% were triplets. From 1991 to 1995 the number of embryos transferred to a woman's uterus was limited to three. This cut the rate of triplets to 4.4% but made hardly any difference to the proportion of twins, which still accounted for more than quarter of deliveries.

From 1996 to 1999 more and more patients had only two embryos transferred (44% of women in 1999). The delivery rate increased slowly, the triplet rate dropped to 2.3% and the proportion of twins fell slightly to 22.5%.

However, single embryos are only appropriate according to FIVNAT data if the embryos are transferred late in the culture process when a pregnancy rate of over 32% is possible as against less than 23% if the embryo is transferred at only day 2 of its fertilisation. Lead investigator Professor Jean Luc Pouly from the University Hospital of Clermont-Ferrand, concluded: "Even with an important limitation on the numbers of embryos transferred, the problem of multiple pregnancy will remain an important public health challenge for as long as we don't elect to transfer only one single embryo."

Abstract no: O-186 (Tuesday 17.45hrs CET Hall EI): URL:

Dutch team find single embryo transfer is as successful as two in achieving pregnancy

A Dutch team of fertility experts has preliminary evidence that transferring a single embryo to a woman's uterus seems as good a strategy for achieving a successful pregnancy as transferring two embryos at once.

First results of research by a team from the University Medical Centre in Nijmegen showed that there was an almost identical success rate. Of 43 patients so far included in the study, the group with a single egg transferred achieved a pregnancy rate of 27.3% after one cycle and 36.4% after two cycles, while the group which had a single cycle involving two eggs being transferred achieved a pregnancy rate of 28.6% (with two twin pregnancies).

A member of the research team, Ms Marieke Lukassen, told the ESHRE conference that multiple pregnancies were a major risk of assisted reproduction and that single embryo transfer would theoretically be the best policy to avoid the medical, social and economic consequences.

"However, before implementing this policy we have to determine an efficient strategy. So, in this study we compared the pregnancy rate after a maximum of two IVF cycles with a single embryo transfer with the pregnancy rate after one IVF cycle with double embryo transfer. There was no statistically significant difference between the two groups.

"We've concluded from these preliminary results that performing two IVF treatments transferring a single embryo may be an attractive alternative to the double embryo strategy."

She said the study would continue in order to confirm these findings.
Abstract no: 0-005 (Monday 10.30hrs CET Hall A) URL:

Further information:

Press Office: (Sunday 30 June -Wednesday 3 July)
Margaret Willson, Emma Mason, Janet Blümli
Tel: +43 (0) 1 260 69 2010 or +43 (0) 1 260 69 2011 Fax: +43 (0) 1 260 69 2012

European Society of Human Reproduction and Embryology

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