IVF in the US: multiple gestation, economic competition, and the necessity of excess

Refuting a misguided campaign against the goal of single-embryo transfer and singleton birth in assisted reproduction

Much recent progress has been made by assisted reproductive technology (ART) professionals toward minimizing the incidence of multiple pregnancy following ART treatment. While a healthy singleton birth is widely considered to be the ideal outcome of such treatment, a vocal minority continues a campaign to advocate the benefits of multiple embryo transfer as treatment and twin pregnancy as outcome for most ART patients. Proponents of twinning argue four points: that patients prefer twins, that multiple embryo transfer maximizes success rates, that the costs per infant are lower with twins and that one twin pregnancy and birth is associated with no higher risk than two consecutive singleton pregnancies and births. We find fault with the reasoning and data behind each of these tenets. First, we respect the principle of patient autonomy to choose the number of embryos for transfer but counter that it has been shown that better patient education reduces their desire for twins. In addition, reasonable and evidentially supported limits may be placed on autonomy in exchange for public or private insurance coverage for ART treatment, and counterbalancing ethical principles to autonomy exist, especially beneficence (doing good) and non-maleficence (doing no harm). Second, comparisons between success rates following single-embryo transfer (SET) and double-embryo transfers favor double-embryo transfers only when embryo utilization is not comparable; cumulative pregnancy and birth rates that take into account utilization of cryopreserved embryos (and the additional cryopreserved embryo available with single fresh embryo transfer) consistently demonstrate no advantage to double-embryo transfer. Third, while comparisons of costs are system dependent and not easy to assess, several independent studies all suggest that short-term costs per child (through the neonatal period alone) are lower with transfers of one rather than two embryos. And, finally, abundant evidence conclusively demonstrates that the risks to both mother and especially to children are substantially greater with one twin birth compared with two singleton births. Thus, the arguments used by some to promote multiple embryo transfer and twinning are not supported by the facts. They should not detract from efforts to further promote SET and thus reduce ART-associated multiple pregnancy and its inherent risks.

Elective single embryo transfer: a 6-year progressive implementation of 784 single blastocyst transfers and the influence of payment method on patient choice

OBJECTIVE

To evaluate efforts to reduce twin pregnancies through progressive implementation of elective single embryo transfer (eSET) among select patients over a 6-year period.

DESIGN

Retrospective review.

SETTING

Private practice IVF center.

PATIENT(S)

Infertile women undergoing 15,418 consecutive IVF-ET cycles.

INTERVENTION(S)

IVF-ET, including blastocyst-stage eSET among select patients with good prognosis and high risk of multiple pregnancy.

MAIN OUTCOME MEASURE(S)

Pregnancy, multiple pregnancy, method of payment.

RESULT(S)

Pregnancy rates were similar for autologous eSET versus double-blastocyst transfer (65% vs. 63%), while twin rates were much lower (1% vs. 44%). For recipients of donor oocytes, pregnancy rates were slightly lower with eSET (63% vs. 74%), while twin rates were much lower (2% vs. 54%). There was no decrease in overall pregnancy rates, despite a dramatic rise in eSET use over time (1.5% to 8.6% of all autologous transfers and 2.0% to 22.5% of all transfers to donor oocyte recipients between 2002 and 2007). Overall singleton pregnancy rates increased, while twin pregnancy rates declined significantly over time. Use of eSET was significantly more common among patients with insurance coverage or who were participating in our Shared Risk money-back guarantee program.

CONCLUSION(S)

Selective eSET use among good-prognosis patients can significantly reduce twin pregnancies without compromising pregnancy rates. Patients are more likely to choose eSET when freed from financial pressures to transfer multiple embryos.

The effects of competition on assisted reproductive technology outcomes

OBJECTIVE

To evaluate the relationship between competition among fertility clinics and assisted reproductive technology (ART) treatment outcomes, particularly multiple births.

DESIGN

Using clinic-level data from 1995 to 2001, we examined the relationship between competition and clinic-level ART outcomes and practice patterns.

SETTING

National database registry.

PATIENT(S)

Clinics performing ART.

INTERVENTION(S)

The number of clinics within a 20-mile (32.19-km) radius of a given clinic.

MAIN OUTCOME MEASURE(S)

Clinic-level births, singleton births, and multiple births per ART cycle; multiple births per ART birth; average number of embryos transferred per cycle; and the proportion of cycles for women under age 35 years.

RESULT(S)

The number of competing clinics is not strongly associated with ART birth and multiple birth rates. Relative to clinics with no competitors, the rate of multiple births per cycle is lower (-0.03 percentage points) only for clinics with more than 15 competitors. Embryo transfer practices are not statistically significantly associated with the number of competitors. Clinic-level competition is strongly associated with patient mix. The proportion of cycles for patients under 35 years old is 6.4 percentage points lower for clinics with more than 15 competitors than for those with no competitors.

CONCLUSION(S)

Competition among fertility clinics does not appear to increase rates of multiple births from ART by promoting more aggressive embryo transfer decisions.

A 47-year-old woman with fertility problems who desires a multiple pregnancy

Mrs Z is a 47-year-old woman with long-standing infertility who is about to undergo in vitro fertilization (IVF) using donor oocytes from an anonymous donor. She has already undergone an IVF cycle with her own oocytes and an IVF cycle using donor oocytes from a known donor without a successful pregnancy. Mrs Z has been advised by her infertility physician to consider the transfer of a single embryo, but she does not wish to decrease her likelihood of conception, and, after her long and expensive infertility saga, wishes to conceive twins. The science of IVF has evolved significantly in the last several years, increasing the likelihood of successful pregnancy and reducing the need to transfer more than 1 embryo with its inherent risks of multiple pregnancy. The state of the science and why patients may continue to want multiple embryos transferred, including costs and lack of insurance coverage for infertility treatments, are discussed.

Why do couples refuse or discontinue ART?

The first child born after in-vitro fertilisation, (IVF)-treatment, just passed its 26th birthday in July 2004. Since that birth-assisted reproduction techniques (ART) became a practicable technology, they had been used all over the world, and more than 2 million children were born after IVF-treatment. Despite all success in this field, ART is neither accepted nor used for all infertile couples, although this might be the only possibility of becoming pregnant. Two different kinds of ART refusal are distinguishable: the primary refusal being for financial, psychosocial, moral, ethical and medical reasons including the risk of severe ovarian hyperstimulation syndrome, the risk of multiple pregnancies and the risk of malformations. The secondary refusal includes dropouts after one or more unsuccessful IVF-treatments mainly influenced by the outcome of previous cycles (prognostic factors: oocyte and embryo count, embryo quality, females age) associated with psychological and emotional aspects. However, financial factors seem to be the most potent reasons for ART-refusal.

Effects of competition among fertility centers on pregnancy and high-order multiple gestation rates

OBJECTIVE

To measure the effect of competition among fertility centers on pregnancy and high-order multiple (HOM) gestation rates after IVF.

DESIGN

Retrospective cohort study.

SETTING

Four hundred eight fertility clinics registered with the Society for Assisted Reproductive Technology as providing IVF services in 2000. Competition was defined as number of clinics in a geographically defined area. Demand for services was based on the population of reproductive-aged women.

PATIENT(S)

Three hundred eighty-one fertility clinics reporting clinical outcomes.

INTERVENTION(S)

Pregnancy rates, HOM gestation rates, population of reproductive-aged women, and number of competing clinics were calculated for each clinic from Society for Assisted Reproductive Technology and census data.

MAIN OUTCOME MEASURE(S)

The clinic HOM gestation rate (percentage of pregnancies that were HOM) and age-adjusted pregnancy rate.

RESULT(S)

The number of clinics in an area of competition ranged from 1 to 22. The HOM gestation rate per clinic ranged from 0% to 50%. As demand increased, competition increased. As competition increased, the number of HOM pregnancies per clinic decreased. In areas of low competition (1 to 2 clinics) the clinic HOM gestation rate was 8.43%, in areas of intermediate competition (3-7 clinics) 8.39%, and in areas of high competition (8-22 clinics) 8.24%. In areas with intermediate demand, high levels of competition resulted in fewer HOM pregnancies than intermediate competition (relative risk 0.56, 95% confidence interval 0.36-0.89) or low levels of competition (RR 0.57, 95% confidence interval 0.35-0.94). Age-adjusted pregnancy rates did not differ by level of competition.

CONCLUSION(S)

According to these data, the risk of HOM gestation decreases with increasing competition among clinics; however, pregnancy rates are unaffected.

Single embryo transfer and IVF/ICSI outcome: a balanced appraisal

This review considers the value of single embryo transfer (SET) to prevent multiple pregnancies (MP) after IVF/ICSI. The incidence of MP (twins and higher order pregnancies) after IVF/ICSI is much higher (approximately 30%) than after natural conception (approximately 1%). Approximately half of all the neonates are multiples. The obstetric, neonatal and long-term consequences for the health of these children are enormous and costs incurred extremely high. Judicious SET is the only method to decrease this epidemic of iatrogenic multiple gestations. Clinical trials have shown that programmes with >50% of SET maintain high overall ongoing pregnancy rates ( approximately 30% per started cycle) while reducing the MP rate to <10%. Experience with SET remains largely European although the need to reduce MP is accepted worldwide. An important issue is how to select patients suitable for SET and embryos with a high putative implantation potential. The typical patient suitable for SET is young (aged <36 years) and in her first or second IVF/ICSI trial. Embryo selection is performed using one or a combination of embryo characteristics. Available evidence suggests that, for the overall population, day 3 and day 5 selection yield similar results but better than zygote selection results. Prospective studies correlating embryo characteristics with documented implantation potential, utilizing databases of individual embryos, are needed. The application of SET should be supported by other measures: reimbursement of IVF/ICSI (earned back by reducing costs), optimized cryopreservation to augment cumulative pregnancy rates per oocyte harvest and a standardized format for reporting results. To make SET the standard of care in the appropriate target group, there is a need for more clinical studies, for intensive counselling of patients, and for an increased sense of responsibility in patients, health care providers and health insurers.

Trends in embryo-transfer practice and in outcomes of the use of assisted reproductive technology in the United States

BACKGROUND

During the past decade in the United States, increasing attention has been paid to lowering the incidence of multiple gestations resulting from the use of assisted reproductive technology. To determine whether such efforts have been successful, we assessed national trends in embryo-transfer practice patterns and in outcomes after the use of assisted reproductive technology.

METHODS

We analyzed data on outcomes of assisted reproductive technology procedures as reported to the Centers for Disease Control and Prevention from 1995 to 2001 by fertility clinics in the United States. We also analyzed data from the National Center for Health Statistics on the rates of twin births and triplet or higher-order multiple births.

RESULTS

From 1995 to 2001 in the United States, the number of infertility clinics, the number of fresh-embryo cycles initiated, and the number of fresh-embryo transfers increased steadily. The average number of embryos transferred per cycle began decreasing in 1997, with the steepest decline (an 11.1 percent decrease) between 1998 and 1999. In contrast, the number of pregnancies and live births per cycle during the period from 1995 to 2001 steadily increased. Even though the percentage of pregnancies with twins did not change significantly between 1997 and 2001, the percentage of pregnancies with three or more fetuses significantly decreased every year, with the steepest decline (a 20.8 percent decrease) between 1998 and 1999, after the publication in 1998 of the American Society for Reproductive Medicine guidelines for embryo transfer.

CONCLUSIONS

Since 1997 in the United States, there have been consistent decreases in both the number of embryos transferred per cycle and the percentage of pregnancies with three or more fetuses, as well as a consistent increase in the percentage of live births per cycle.

Time to revolutionize the triggering of ovulation

Methods used for ovarian stimulation constantly change with advances in gonadotrophin therapy. In this Commentary, an appeal is made for more attention to the use of LH for the induction of ovulation. Its typical characteristics during the LH surge are finely balanced to induce normal ovulation and luteinization. It does not induce ovarian hyperstimulation, for example. The recent commercial availability of recombinant LH (LHr) offers a chance of escaping from the use of urinary human chorionic gonadotrophin (HCG) and its varied forms such as those with a shorter half-life. It should also avoid the weakly effective bursts of FSH and LH and weak luteal phases released associated with the use of gonadotrophin-releasing hormone agonists. Currently, large dosages of LHr are needed to match the endocrine events typical of inducing ovulation by the endogenous LH surge. In the interests of patients' safety and improved forms of luteal phase endocrinology, research should be devoted to improving the properties of rLH to make it induce surges similar to endogenous discharges. This would replace the current use of HCG to induce ovulation, with its attendant risks of ovarian hyperstimulation and luteal phase anomalies.

Ethical considerations in newer reproductive technologies

Ethics is an essential dimension of newer reproductive technologies. In this rapidly evolving field, there is a need for an ethical framework to guide both clinical practice and research. In this article, we provide such a framework that incorporates ethical principles, professional virtues, and the concept of the fetus as a patient. We then apply this framework to an important current clinical issue: the number of embryos to be transferred during in vitro fertilization; in addition to an emerging research issue: gene transfer research on in vitro embryos.

Does insurance coverage decrease the risk for multiple births associated with assisted reproductive technology?

OBJECTIVE

To determine whether insurance coverage for ART is associated with transfer of fewer embryos and decreased risk of multiple births.

DESIGN

Retrospective cohort study of a population-based sample of IVF procedures performed in six U.S. states during 1998.

SETTING

Three states with mandated insurance coverage (Illinois, Massachusetts, and Rhode Island) and three states without coverage (Indiana, Michigan, and New Jersey).

PARTICIPANT(S)

Seven thousand, five hundred sixty-one IVF transfer procedures in patients < or = 35 years of age.

MAIN OUTCOME MEASURE(S)

Number of embryos transferred, multiple-birth rate, triplet or higher order birth rate, and triplet or higher order gestation rate.

RESULT(S)

A smaller proportion of procedures included transfer of three or more embryos in Massachusetts (64%) and Rhode Island (74%) than in the noninsurance states (82%). The multiple-birth rate in Massachusetts (38%) was less than in the noninsurance states (43%). The insurance states all had protective odds ratios for triplet or higher order births, but only the odds ratio (0.2) for Massachusetts was significant. This decreased risk in Massachusetts resulted from several factors, including a smaller proportion of patients with three or more embryos transferred, lower implantation rates when three or more embryos were transferred, and greater rates of fetal loss among triplet or higher order gestations.

CONCLUSION(S)

Insurance appears to affect embryo transfer practices. Whether this translates into decreased multiple birth risk is less clear.

Too many twins, triplets, quadruplets, and so on: a call for new priorities

Assisted reproductive technology has enabled thousands of infertile couples to experience the joys of parenthood. At various times, however, significant problems have come to light concerning the providing of infertility treatment in the United States. An early problem was misleading advertising by some infertility programs, particularly in regard to pregnancy success rates. This unacceptable activity suggested the need for more oversight of assisted reproductive technology and prompted the passage of a federal law requiring the reporting of success rates in a standardized format. Another problem, one that was especially disturbing, was the transfer of preembryos to infertile women at the University of California, Irvine, without the consent of the progenitor couples. Disclosure of these events added fuel to the debate over whether assisted reproductive technology should be subject to greater governmental regulation.

Insurance coverage and outcomes of in vitro fertilization

BACKGROUND

Although most insurance companies in the United States do not cover in vitro fertilization, a few states mandate such coverage.

METHODS

We used 1998 data reported to the Centers for Disease Control and Prevention by 360 fertility clinics in the United States and 2000 U.S. Census data to determine utilization and outcomes of in vitro fertilization services according to the status of insurance coverage.

RESULTS

Of the states in which in vitro fertilization services were available, 3 states (31 clinics) required complete insurance coverage, 5 states (27 clinics) required partial coverage, and 37 states plus Puerto Rico and the District of Columbia (302 clinics) required no coverage. Clinics in states that required complete coverage performed more in vitro fertilization cycles than clinics in states that required partial or no coverage (3.35 vs. 1.46 and 1.21 transfers per 1000 women of reproductive age, respectively; P<0.001) and more transfers of frozen embryos (0.43 vs. 0.30 and 0.20 per 1000 women of reproductive age, respectively; P<0.001). The percentage of cycles that resulted in live births was higher in states that did not require any coverage than in states that required partial or complete coverage (25.7 percent vs. 22.2 percent and 22.7 percent, respectively; P<0.001), but the percentage of pregnancies with three or more fetuses was also higher (11.2 percent vs. 8.9 percent and 9.7 percent, respectively; P=0.007). The number of fresh embryos transferred per cycle was lower in states that required complete coverage than in states that required partial or no coverage (P=0.001 and P<0.001, respectively).

CONCLUSIONS

State-mandated insurance coverage for in vitro fertilization services is associated with increased utilization of these services but with decreases in the number of embryos transferred per cycle, the percentage of cycles resulting in pregnancy, and the percentage of pregnancies with three or more fetuses.

Ethical dimensions of the number of embryos to be transferred in in vitro fertilization

PURPOSE

We propose an ethically justified policy for the number of embryos to transfer in an in vitro fertilization (IVF), by considering fourfactors: medical outcomes, patient's preferences, costs, and market forces of providers.

METHODS

We develop an ethical framework that incorporates three ethical principles: beneficence, respect for autonomy, and justice; and three professional virtues: integrity, compassion, and self-sacrifice.

RESULTS

This ethical framework calls for an informed consent process for IVF that provides: information about medical outcomes; information about the risks of multiple gestation; the opportunity to weigh the goal of pregnancy and live birth against the medical and moral risks of multiple gestation; evidence-based recommendations; protection of the woman from potentially coercive influences; and discussion of living with infertility and going to better centers.

CONCLUSION

The number of embryos to be transferred in IVF should mainly be a function of the pregnant women's informed decision. Limiting the number of transferred embryos to two in all cases is not ethically justified at this time.

Avoiding multiple pregnancies in ART: multiple pregnancies: a test case for the moral quality of medically assisted reproduction

Although most professional societies have issued guidelines to diminish the number of embryos to be transferred during assisted reproduction techniques, the incidence of multiple pregnancies remains unacceptably high. The negative psychological, social and medical consequences for the patients and their offspring easily outweigh the benefits in terms of increased success rates. Multiple pregnancies would never be tolerated if the 'best interest of the child' standard was applied as strictly to these consequences, as it is to controversial family forms. The persistence of high multiple pregnancy rates is largely due to the pressure brought to bear on the physicians to increase the overall success rate. The fertility specialist should inform the patients about the risks and benefits of a multiple transfer but ultimately the specialist should decide how many embryos to transfer. Multifetal reduction is an ethically acceptable solution if, and only if, the physician has taken all reasonable steps to prevent the occurrence of a multiple pregnancy. Finally, an additional strategy to decrease the incidence of multiple pregnancies is proposed, i.e. to extend the professional responsibility of the fertility specialist to all steps of procreation including pregnancy, birth and neonatal care.

Less is more: the risks of multiple births. The Institute for Science, Law, and Technology Working Group on Reproductive Technology

OBJECTIVE

To review the medical, social, and financial risks caused by the birth of multiples that need to be addressed in policy and practice.

RESULT(S)

Many risks of multiple births are described in the literature. The medical risks to the offspring include death, low birth weight, deformational plagiocephaly, and other physical and mental disabilities. Risks to the women include premature labor, premature delivery, pregnancy-induced hypertension, toxemia, gestational diabetes, and vaginal-uterine hemorrhage. Children born in multiples face difficulty socializing, developmental delays, and behavioral problems, whereas their parents risk exhaustion, depression, and anxiety. In addition to personal costs faced by families, society often bears the financial costs of overburdened hospitals, caps on insurance and/or inability of parents to cover expenses.

CONCLUSION(S)

Multiple births present potential acute and long-term medical risks to the pregnant woman and her children. However, more long-term follow-up research and more research on outcomes with higher-order multiples are needed. In designing practices and policies to improve the success of IVF while reducing the risk of multiples, it is important to balance the many interests involved. At a minimum, providers and patients need to be educated about the risks of multiple gestation so that steps can be taken to prevent adverse outcomes.

Avoiding multiple pregnancies in ART: a plea for single embryo transfer

It has been generally accepted that triplets after IVF/intracytoplasmic sperm injection (ICSI) can and should be avoided by adopting a standard strategy of replacing no more than two embryos. However, there is an increasing awareness of the risks and costs and of the epidemic size of twin pregnancies after IVF/ICSI. This has resulted in efforts to replace no more than one embryo. However, this approach has been hampered by our relative inability to identify embryos with a very high implantation potential. To identify such embryos, a number of strategies are being considered, both at the two pronuclear (2PN), early cleavage and the blastocyst stages. At the 2PN stage, the polarity characteristics of the nucleoli have been shown to be correlated with a high implantation rate. Similarly, the morphological characteristics at day 2 and 3 have been used to describe top quality embryos in approximately 75% of all IVF/ICSI cycles. Blastocyst culture has resulted in very high implantation rates in the hands of some authors. No approach has shown its superiority at present, but initial experience with single embryo transfer (SET) at the early cleavage stage by Scandinavian and Belgian groups shows that an ongoing pregnancy rate of 35% and more can be achieved. Proper identification of patients at risk of a twin pregnancy after double embryo transfer is equally important. It is clear that mainly young patients (aged <34 years) during their first, perhaps first two, IVF/ICSI cycles constitute the main population at risk (responsible for >80% of all twins) and are the main target group for twin prevention by SET of a top quality embryo at whatever stage. Therefore, in our opinion, although a further fine-tuning of both embryo and patient characteristics relating to a high risk for (twin) pregnancy is desirable, SET should be introduced carefully and progressively in each IVF/ICSI programme from now on. Correct counselling is very important and both public and private insurers will have to join in the discussion.

The interpretation and use of statistics in assisted reproductive technologies

This article has discussed some of the uses and limitations of currently available statistics for ART programs. A well-known example from statistics states that flipping a coin will produce "heads" 50% of the time and "tails" 50% of the time, provided that the coin is flipped enough times. Experience also shows that the result of individual flips cannot be predicted. Similarly, in ART, statistics can only give general probabilities and not meaningful predictions of the outcome of any particular cycle. Patients should be aware of the limits of statistical analysis as it applies to their individual treatment.

Reducing the risk of high-order multiple pregnancy after ovarian stimulation with gonadotropins

BACKGROUND

The incidence of multiple gestation after therapy for infertility is especially high among women in whom ovulation is induced with gonadotropins. Whether the number of high-order multiple pregnancies (those with three or more fetuses) can be reduced is not known.

METHODS

We analyzed data on 3347 consecutive treatment cycles in 1494 infertile women, 441 of which resulted in pregnancy. The data collected included the peak serum estradiol concentration, the number of follicles 16 mm or larger in diameter, and the total number of follicles on the day of induction of ovulation with human chorionic gonadotropin. Receiver-operating-characteristic curves and ordinal logistic-regression analyses were used to identify values that predicted multiple conceptions.

RESULTS

Among the 441 pregnancies, 314 resulted from the conception of singletons, 88 of twins, 22 of triplets, 10 of quadruplets, 5 of quintuplets, and 2 of sextuplets. Neither the number of follicles 16 mm or larger nor peak serum estradiol concentrations greater than 2000 or 2500 pg per milliliter (7342 or 9178 pmol per liter) (the cutoff values currently in wide use) were significantly associated with the incidence of high-order multiple pregnancy. However, increasing total numbers of follicles and increasing peak serum estradiol concentrations correlated significantly with an increasing risk of high-order multiple pregnancy (P<0.001), as did younger age (P=0.008). The risk of high-order multiple pregnancy was significantly increased in women with a peak serum estradiol concentration of 1385 pg per milliliter (5084 pmol per liter) or higher (multivariate odds ratio, 1.9; 95 percent confidence interval, 1.3 to 2.8) or with seven or more follicles (multivariate odds ratio, 2.1; 95 percent confidence interval, 1.2 to 3.9) on the day of induction of ovulation.

CONCLUSIONS

Gonadotropin stimulation that is less intensive than is currently customary may reduce the incidence of high-order multiple pregnancy in infertile women, though only to a limited extent and at the expense of overall pregnancy rates.

The influence of supernumerary embryos on the clinical outcome of IVF cycles

PURPOSE

To assess the influence of the presence of quality supernumerary embryos on the clinical outcome and risk of multiple conception in patients having their first in vitro fertilization (IVF) cycle.

METHODS

Retrospective cohort study of 1448 women having their first IVF treatment cycle who received 4004 embryos where at least six embryos were available for transfer treated in an Assisted Conception Unit based in a large teaching hospital.

RESULTS

The replacement of three rather than two embryos to women under 35 years who had good-quality supernumerary embryos resulted in a higher twin (12.5 vs. 11.9%) and triplet birth rates (2.1 vs. 0%), without significantly improving the clinical pregnancy (50.5 vs. 45.2%) or total live birth rates (38.9 vs. 35.7%). In the absence of quality spare embryos, these women who had three rather than two embryos replaced had a significantly higher clinical pregnancy rate (39.3 vs. 28.8%; P = 0.04), total live birth (32.7 vs. 19.4%; P = 0.02) and singleton birth rate per cycle (20.8 vs. 14.4%; P = 0.04), without significantly influencing the multiple birth rate. In women over 35 years, the replacement of three instead of two embryos in the presence or absence of quality supernumerary embryos led to a significant improvement in clinical outcome, without being associated with a concurrent increase in the multiple birth rate. Women in both age groups who had either two or three embryos replaced in the presence of quality supernumerary embryos had a notably better clinical outcome compared with their counterparts who had the same number of embryos replaced, but with no quality embryos to spare.

CONCLUSIONS

The presence of good-quality supernumerary embryos can be used as a reference to determine the optimal number of embryos to transfer and as an indicator of the probability of success of an individual couple in a given cycle. Optimal pregnancy rates and simultaneous reduction of multiple gestation can be achieved with a flexible embryo replacement policy that is based on embryo quality, maternal age, and the presence or absence of surplus quality embryos.

Prevention of twin pregnancy after in-vitro fertilization or intracytoplasmic sperm injection based on strict embryo criteria: a prospective randomized clinical trial

A prospective randomized study comparing single embryo transfer with double embryo transfer after in-vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) was carried out. First, top quality embryo characteristics were delineated by retrospectively analysing embryos resulting in ongoing twins after double embryo transfer. A top quality embryo was characterized by the presence of 4 or 5 blastomeres at day 2 and at least 7 blastomeres on day 3 after insemination, the absence of multinucleated blastomeres and <20% cellular fragments on day 2 and day 3 after fertilization. Using these criteria, a prospective study was conducted in women <34 years of age, who started their first IVF/ICSI cycle. Of 194 eligible patients, 110 agreed to participate of whom 53 produced at least two top quality embryos and were prospectively randomized. In all, 26 single embryo transfers resulted in 17 conceptions, 14 clinical and 10 ongoing pregnancies [implantation rate (IR) = 42.3%; ongoing pregnancy rate (OPR) = 38.5%] with one monozygotic twin; 27 double embryo transfers resulted in 20 ongoing conceptions with six (30%) twins (IR = 48.1%; OPR = 74%). We conclude that by using single embryo transfer and strict embryo criteria, an OPR similar to that in normal fertile couples can be achieved after IVF/ICSI, while limiting the dizygotic twin pregnancy rate to its natural incidence of <1% of all ongoing pregnancies.

Colour Doppler indices of follicular blood flow as predictors of pregnancy after in-vitro fertilization and embryo transfer

Peak systolic velocity (PSV) of individual follicles has been correlated with oocyte recovery, fertilization rate and embryo quality [in women undergoing in-vitro fertilization (IVF) and embryo transfer]. The present study assessed the role of quantitative and qualitative indices of follicular vascularity in predicting pregnancy after IVF and embryo transfer. A total of 106 women undergoing IVF treatment for infertility who were considered to be at risk of failure (>37 years of age, history of low response to gonadotrophin stimulation, or multiple failed IVF cycles) constituted the study group. PSV was measured from the three largest follicles on both the right and left ovaries on the day of human chorionic gonadotrophin (HCG) administration using an Acuson Sequoia with a 4-8 MHz transvaginal probe. The quality of follicular flow was graded from 1 to 4 according to the amount of visible colour flow around the follicle (grade 1 when one-quarter of the follicle, grade 2 when one-half, grade 3 when three-quarters, and grade 4 when the entire follicle was surrounded by colour). Clinical pregnancies resulted in 11 (10%) of the 106 high-risk women. Women who had PSV >/= 10 cm/s in at least one follicle on the day of HCG administration more often became pregnant than those with PSV <10 cm/s (P = 0.05). All pregnancies occurred in women with grade 3 or 4 follicular blood flow. Qualitative as well as quantitative measurements of follicular flow predict pregnancy after IVF and embryo transfer.

Probabilities for singleton and multiple pregnancies after in vitro fertilization

OBJECTIVE

To help physicians provide risk estimates for specific pregnancy outcomes.

DESIGN

Computation of exact binomial probabilities for singleton and multiple pregnancies as a function of two inputs: the number of embryos transferred and the implantation rate. Inputs were varied over the range of values reported in the literature.

MAIN OUTCOME MEASURE(S)

Probabilities for a singleton pregnancy (none), a multiple pregnancy (Pmult), and no pregnancy (Pnone) after one IVF cycle.

RESULT(S)

Given a 30% implantation rate and three embryos transferred, Pone=.44, Pmult=.22, and Pnone=.34. Although further increasing the number of embryos transferred increases the chance of pregnancy, it also raises the probability of a multiple pregnancy and lowers the chance of a singleton pregnancy. Although varying the implantation rate changes the specific probability estimates, the same trade-off persists.

CONCLUSION(S)

Those who consider an IVF "success" to be a singleton pregnancy should be attentive to the number of embryos transferred. Infertility therapy may be one area in medicine where more is not necessarily better.

Reducing the risk of multiple births by transfer of two embryos after in vitro fertilization

BACKGROUND

In vitro fertilization is associated with a high risk of multiple births, which is a direct consequence of the number of embryos transferred. However, other factors that contribute to the risk are not well defined.

METHODS

Using the data base established by the Human Fertilization and Embryology Authority in the United Kingdom, we studied the factors associated with an increased risk of multiple births in 44,236 cycles in 25,240 women. The factors included the woman's age, the cause and duration of infertility, previous attempts at in vitro fertilization, previous live births, number of eggs fertilized, and number of embryos transferred.

RESULTS

Older age, tubal infertility, longer duration of infertility, and a higher number of previous attempts at in vitro fertilization were all associated with a significantly decreased chance of a birth and of multiple births. Previous live birth was associated with an increased chance of a birth but not of multiple births. The higher the number of eggs fertilized, the higher the likelihood of a live birth. When more than four eggs were fertilized, there was no increase in the birth rate for women receiving three transferred embryos as compared with those receiving two, but there was a considerable increase in the rate of multiple births when three were transferred (odds ratio, 1.6; 95 percent confidence interval, 1.5 to 1.8).

CONCLUSIONS

Among women undergoing in vitro fertilization, the chances of a live birth are related to the number of eggs fertilized, presumably because of the greater selection of embryos for transfer. When more than four eggs are fertilized and available for transfer, the woman's chance of a birth is not diminished by transferring only two embryos. Transferring more embryos increases the risk of multiple births.