Single Embryo Transfer in IVF

Helping patients to make informed decisions

By Christopher Newton, Ph.D., Valter Feyles, M.D., Joanna McBride, M.A.

Fall 2007

Introduction

In Vitro Fertilization (IVF) treatment has offered patients the chance to have a family where natural conception is not possible. At the same time, concerns have been raised about the increased risk of multiple pregnancy associated with this technology. The main reason for this is the usual practice of transferring more than one embryo at a time to the woman’s uterus. However, as medical knowledge and techniques have improved, the number of embryos transferred to the uterus during IVF treatment has gradually decreased. For example, twenty years ago it was not unusual to transfer up to five embryos during a treatment cycle. Now the transfer of two embryos, for women under the age of 35, is common practice in Canada.

Despite these changes in medical practice, studies have reported that in Europe in 2001, 26% of all pregnancies following IVF resulted in a multiple birth. In Canada in 2001, 33% of all IVF births were multiple deliveries and the figure for the United States in 2003 (36%) is even higher. To put it in perspective, the chance of a multiple pregnancy after IVF treatment is approximately 15 times higher than after natural conception.

Risks of multiple pregnancy

Adding further to the problem, the risks associated with a multiple pregnancy often go largely unrecognized by the general public, particularly in the case of twins. For example, most people would be surprised to hear that the neonatal mortality rate is five times higher in twins than in singletons. Twins and triplets are more likely to be born preterm, with 8—15% born very premature (<33 weeks) and 7—11% born with very low birth weight (<1500 g). Complications associated with low birth weight include increased risk for respiratory difficulties, cerebral palsy, deafness, blindness, and cognitive impairment. Compared to singletons, twins have been shown to be at increased risk for delayed language development and lower verbal intelligence.

When carrying a multiple pregnancy, women are more at risk of developing preeclampsia (a disorder involving severe high blood pressure). Following a multiple birth, mothers are at increased risk for depression and experience higher parenting stress.

Financial costs

In addition to the medical risks, multiple births place a considerable financial burden on the health care system. In 2000 in the United States, of approximately 10 billion dollars spent in hospital care for newborns, 57% was spent on 9% of infants delivered preterm. In the same study it was estimated that $640 million was spent on costs associated with multiple births from IVF procedures, whereas $470 million was spent on the IVF procedures themselves.

It has been estimated that health care costs for the first six weeks after birth alone are five times higher for twins than for singleton infants. Twins are more likely than singletons to be born prematurely, and prematurity is associated with an increased risk of medical complications and an increased number and duration of hospital admissions. Furthermore, the long-term treatment of such medical conditions likely makes the increased costs for twins even higher. It has been estimated that the neonatal costs up to the age of eight years for children born with low birth weight is 13 times greater than for those with normal birth weight.

Single Embryo Transfer

Currently in Canada and the United States, there are no regulatory guidelines or laws concerning the number of embryos to transfer. However, some countries do limit the maximum number to three (Argentina, Belgium, the Czech Republic, Italy, Germany, Latvia, Slovenia, and Spain), and in other countries, the transfer of only two embryos is permitted except in special circumstances (Australia, Denmark, Israel, Norway, New Zealand, and the United Kingdom).

More recently, there has been growing attention given to the option of transferring a single embryo during an IVF treatment cycle. When multiple embryos are available, but the couple chooses to transfer only one embryo, the practice is known as elective single embryo transfer (SET). In this situation, couples may choose to cryopreserve (freeze) their remaining embryos for future IVF cycles.

In fact, some countries have introduced legislation to promote SET. In Belgium, the cost of IVF treatment in women under 36 is covered by national health insurance for the first two cycles, but only if cycles involve SET. In 2003, Sweden passed legislation requiring that, with certain exceptions, all IVF treatment involve only SET. This strategy has virtually eliminated the risk of a multiple birth through IVF treatment.

By comparison, the practice of SET is relatively uncommon in Canada and the United States. In fact, it is estimated that in 2002, less than 1% of IVF cycles in Canada involved single embryo transfer by choice.

Reactions to SET in North America

In North America, reservations about the use of SET seem to take two forms. First, patients and some health care professionals worry that the transfer of a single embryo rather than two or three embryos might reduce the chance of pregnancy, thereby causing increased stress for the couple and possibly increased financial costs. In actual fact, a number of scientific studies have reported similar pregnancy rates and live birth rates following SET compared to double embryo transfer. The results suggested that SET seems well-suited for women who are less than 36 years of age who have from two to four top quality embryos available for transfer. Remaining embryos can then be frozen. When these embryos are thawed and returned, subsequent pregnancies result overall in an equivalent pregnancy rate.

Secondly, some infertility patients see multiple pregnancy and especially twin pregnancy as a desirable outcome. Twins are regarded as a “good news” event, and a means to achieve an instant family. Studies have shown that few patients perceive twin pregnancy as having significant risks. There is also a belief in the health care community that, despite the known risks of a multiple pregnancy, patients would discount these risks and prefer the transfer of multiple embryos. In this age of competition between public and private health care delivery, keeping health care consumers satisfied is not a small concern.

Current research

Following IVF treatment, embryo transfer is a time for shared decision-making, where the couple and their physician balance possible risks and uncertainties to decide the optimal and preferred number of embryos to transfer. However, not much is known about what influences patients’ decisions at this time, whether these decisions are made with all the necessary information at hand, or if relevant information about some of the risks might influence patients’ attitudes and choices.

In our study, we separately interviewed 79 women and 53 men who were participating in IVF treatment. We asked men and women their opinions about personally experiencing a multiple pregnancy and their preferred number of embryos to transfer. We then gave participants information about some of the potential complications associated with multiple pregnancy (preeclampsia, low birth weight, postpartum depression) and the statistical chances that these complications might occur. We then asked men and women again about their views of multiple pregnancy and embryo transfer.

Findings

Following consultation with their physician, more than 90% of women had either two or three embryos transferred. The vast majority (88%) described feeling very satisfied with this outcome. Just over half (51%) felt that their physician had a large or very large influence over the final decision, but 71% of women felt that they too had a large influence. It was also evident that many women want input into this decision. Women who felt that they had much less influence than their physician in making this decision, described feeling less satisfied. Interestingly, men seemed to place less importance on having input into this decision, perhaps seeing it somehow as an area of female expertise.

Few patients in our study had any experience with SET, and at first, only a minority of women (34%) rated SET as a desirable option. In fact, a substantial number of women (30%) initially characterized SET as a very undesirable option. The most popular preference (75% of women) was the transfer two embryos. In addition, before receiving information about the risks associated with twin pregnancy, a substantial number of women (45%) and men (57%) viewed a twin pregnancy as a very desirable option.

We also discovered that there seemed to be two different groups of patients. “Cautious” patients tended to be younger and at first tended to favour the transfer of two embryos. Surprisingly, these women did not have a strong desire for twins, but did believe that transferring more than one embryo increased their personal risk for twins. However, they based their preference on the belief that transferring two embryos rather than one would increase their chance of achieving a pregnancy. Their preference seemed to reflect a desire to increase their chance of getting pregnant while at the same time keeping the risk of a multiple pregnancy at an acceptable level. However, a growing number of scientific studies actually show that transferring two embryos offers no significant advantage over SET in cases where women are younger and have multiple embryos available to transfer. Therefore some patients’ beliefs about ways to increase the chance of pregnancy may not be accurate.

A second group of women seemed to be greater “risk takers” and preferred the transfer of three or even four embryos. They regarded the transfer of two embryos and SET as less desirable. These women tended to be either older, or women who strongly desired a twin pregnancy. Although viewing a twin pregnancy as desirable, they also believed that this was personally unlikely to happen. There has been a considerable amount written in the media about infertility being more prevalent in older women. It is possible that older women (and sometimes their physicians) have been influenced by this information, and choose to transfer a higher number of embryos in the belief that this will increase the chance of pregnancy. Contrary to this widespread belief, research has again suggested that among older women with four fertilized eggs, the transfer of multiple embryos (more than two) did not increase a woman’s chance of becoming pregnant, but did increase her risk of a multiple pregnancy. So again, some patients’ attitudes and preferences may be based on misinformation and these women may actually be underestimating their personal risk of multiple pregnancy.

When we provided men and women with more detailed information about potential complications and the risks associated with multiple pregnancy, their views about SET and twin pregnancy changed. For example, after hearing about risks, more men and women favoured SET compared with the transfer of two embryos. Similarly, the desire for a twin pregnancy also decreased sharply among both women and men.

Currently in Ontario, only women diagnosed with bilateral tubal blockage are able to receive IVF treatment paid for by the Ontario Health Insurance Plan. It has been argued that SET would not be well received and that patients who pay for treatment will prefer to transfer multiple embryos in an effort to succeed as quickly as possible and thereby reduce the financial costs. Interestingly, when we compared women with and without insurance coverage, we found that financial costs of treatment did not influence women’s preferences for embryo transfer. Although money is undoubtedly an important concern for many couples, other factors appear to be more influential.

Conclusions

When trying to decide the best number of embryos to transfer, IVF participants are facing a rather unique, but very important decision. It also seems that the factors that affect these decisions are more complicated than we first thought. Reluctance to consider SET may not simply be a matter of wanting a twin pregnancy. Among many cautious patients, the desire to transfer two embryos may be an effort to strike a balance between a desire to maximize the chance of pregnancy and acceptance of the perceived risks associated with twin pregnancy. If patients believe that their chance of achieving pregnancy will be reduced by SET, resistance to this option could be expected to continue. At the same time, patients may be lacking important information about the personal risks and costs associated even with twin pregnancy. In future, we need to empower IVF patients, by ensuring that they have all the necessary information to be able to make fully informed decisions that are consistent with their own goals and values.

About The Authors

Christopher Newton is a clinical psychologist in the Reproductive Endocrinology and Infertility (REI) Program at University Hospital of the London Health Sciences Centre in London Ontario. With over 19 years experience as a researcher and counselor and in the field of infertility, he has published widely in international research journals. In 2003, he was awarded a 5-year grant by the Canadian Institutes of Health Research (CIHR) to study patient decision making during IVF treatment. Dr. Valter Feyles is the Chair of the REI program at University Hospital and Associate Professor in the Department of Obstetrics & Gynaecology at the University of Western Ontario. Joanna McBride is a Psychological Associate with both infertility counseling and research experience at the London program.

References

1. Newton CR, McBride J, Feyles V, Tekpetey F, Power S. Factors affecting patients’ attitudes towards single and multiple embryo transfer. Fertil Steril 2007; 87: 269- 78.