Success of fertility, embryo number, and in-vitro fertilisation

Elective single embryo transfer- the power of one

Despite the highest historical live birth success rates for couples undergoing in vitro fertilization (IVF), there has been an epidemic of iatrogenic twin and higher order gestation conceived from this treatment. Continued improvement in cryopreservation techniques have allowed preservation of supernumerary embryos for use in future cycles, and refinements in culture systems and embryo selection have resulted in the transfer of fewer embryos while maintaining favorable pregnancy rates. The voluntary transfer of a single high quality embryo, elective single embryo transfer (eSET), has significantly reduced multiple gestation rates and maximized the rate of singleton pregnancy without compromising overall success rates. Although eSET is the standard of care in several developed countries, utilization in the United States has been slow. States with mandated IVF insurance have seen decreases in preterm birth rates yielding down stream health care savings. Herein, the evolution and future applications of this practice to reduce the risk of iatrogenic twins is reviewed.

An analysis of factors influencing the establishment of a clinical pregnancy in an ultrasound-based ambulatory in vitro fertilization program

In the study period (June 1984 to December 1986), 2232 cycles were stimulated in 1294 patients. Ultrasound-directed oocyte recovery (UDOR) was performed as an ambulatory procedure in 1737 (77.8%) cycles, resulting in 1375 embryos transfers (ET). Age, etiology, menstrual cycle length, number of oocytes collected, and number of embryos transferred were important determinants of the outcome. The number of attempts at in vitro fertilization did not affect the clinical pregnancy rate (CPR). In patients receiving four embryos, the CPR appeared to be highest when up to seven embryos were available for transfer. The fertilization rate in an individual cycle had a good prognostic value, the implantation rate being highest when 7 to 9 oocytes were retrieved and greater than 60% of these were fertilized. When 10 or more oocytes were collected, the implantation rate showed a progressive decline, regardless of the fertilization rate. Furthermore, multiple pregnancies failed to occur when greater than 12 oocytes were retrieved or more than eight embryos were available for transfer. These data suggest that, in excessively stimulated cycles, the quality of oocytes and embryos or uterine receptiveness may be suboptimal, and the transfer of more than four embryos is unlikely to increase the success rate.

The successful recovery and fertilization of oocytes from the pouch of Douglas

Two groups of women were studied in whom a proportion of follicles had either ovulated spontaneously (7 women) or ruptured during manipulation at laparoscopy (30 women), and oocytes were recovered from the pouch of Douglas. There were no significant differences in the fertilization rates of oocytes collected in the pouch of Douglas from ovulated follicles, compared with those from the remaining intact follicles [15/20 (75%) vs 14/20 (70%)]. Also, there was no significant difference between the fertilization rate of oocytes from follicles ruptured at the time of oocyte collection and that of oocytes from intact follicles [25/38 (66%) vs 101/140 (72%)]. One woman became pregnant, following the transfer of four four-cell embryos, all derived from spontaneously ovulated oocytes found in the pouch of Douglas. She gave birth to a baby girl. The present study has shown that oocytes may still be retrieved from the pouch of Douglas, despite follicle dispersal; these oocytes can be fertilized; and the embryos derived from ovulated oocytes recovered from the pouch of Douglas may generate an ongoing pregnancy following in vitro fertilization and embryo transfer.

High incidence of preterm births and early losses in pregnancy after in vitro fertilisation. Australian in vitro fertilisation collaborative group

A fertilisation cohort of 244 pregnancies resulting from in vitro fertilisation was reported to a national register by eight units specialising in in vitro fertilisation. Early pregnancy losses were high, with 5% tubal ectopic pregnancies, 18% biochemical pregnancies, and an incidence of spontaneous abortion of 27%. Among pregnancies of at least 20 weeks' gestation 22% were multiple, with 26 pairs of twins and four sets of triplets. The incidence of preterm births was more than three times higher than in the general population. Low birthweight rates were also higher, owing both to preterm births and to multiple pregnancies. The sex ratio and the incidence of major congenital malformations were similar to those in naturally conceived pregnancies. In this series the high fetal losses at all stages of pregnancy suggested maternal reproductive causes and should not be interpreted as being due to factors peculiar to in vitro fertilisation. Further analysis will be necessary when larger numbers are available.

Successful pregnancies from the transfer of pronucleate embryos in an outpatient in vitro fertilization program

Twenty-nine infertile women were given clomiphene citrate (100 mg/day, days 3 to 7), human menopausal gonadotropin (150 IU/day, days 7 to 12 or 13), and human chorionic gonadotropin (2000 IU) for the induction of ovulation. Eggs were collected by laparoscopy and preincubated for 6 hours before being cultured with spermatozoa for fertilization. Approximately 16 to 18 hours after insemination, the eggs that showed two pronuclei were transferred to the patient's uterus. As confirmed by the ultrasonic appearance of a gestational sac, six women who received pronucleate embryos became pregnant, and three pregnancies resulted in normal full-term deliveries. These results confirm that, unlike requirements for most laboratory and farm animals, the requirements of synchrony between the preimplantation human uterus and developing embryos are not very stringent. In vitro fertilization treatment procedures can thus be made simpler by the transfer of embryos at the pronucleate stage.

Current status of human conception in vitro

The scientific and medical advances culminating in the introduction of in vitro fertilization of human oocytes into clinical practice are reviewed. Current methods that use clomiphene, human menopausal gonadotrophin, and both as follicular stimulants, and the endogenous LH surge or an injection of human chorionic gonadotrophin to induce ovulation are described. The effects of multifolliculation, the diurnal rhythm of the LH surge, and the collection of oocytes from the ovary are related to current clinical practice. The success of in vitro fertilization for infertile men and women is considered in relation to the nature of embryonic growth in vitro. Investigations into blastulation, hatching from the zona pellucida and the use of DNA probes for typing embryos are described. The implantation of embryos is the major remaining problem, and physiological and statistical analyses of implantation are given, comparing results from different clinics. The possibility of embryo 'helping' and factors leading to multipregnancy are considered, and details are given of the incidence of abortion and the birth of children. The use of immature oocytes, the frozen-storage of embryos and methods of raising the chance of implantation are described briefly.

Comparison of the outcome of ovulation induction therapy in an in vitro fertilization program employing a low-dose and an individually adjusted high-dose schedule of human menopausal gonadotropins

A low-dose "nonsuperovulation" scheme of ovulation induction (schedule 1: 15 treatment cycles in 13 women) was compared to a high-dose, individually adjusted "controlled-superovulation" scheme of human menopausal gonadotropin administration (schedule 2: 18 treatment cycles in 17 women, with four women also having been treated under schedule 1). In schedule 2 more human menopausal gonadotropin was employed, 17 beta-estradiol plasma levels were higher, and more ova were retrieved per treatment cycle (p less than 0.01) with a higher rate of mature ova (p = 0.001). Also, under this schedule all treatment cycles resulted in successful retrieval of ova, whereas under schedule 1, four cycles (27%) were abandoned before laparoscopy because the follicles had ovulated (p = 0.03). Furthermore, the proportion of embryos cleaving to the two- to four-cell stage were higher under schedule 2 (38 of 53, or 72%) as compared to schedule 1 (13 of 25, or 52%), but this was not statistically significant (p = 0.07). Two pregnancies were conceived under schedule 2 giving a rate of 11% per treatment cycle. It was concluded that schedule 2, the individually adjusted controlled-superovulation scheme of human menopausal gonadotropin administration, was the superior technique of ovulation induction in an in vitro fertilization program.