Blastocyst transfer has been suggested to improve implantation rate without affecting pregnancy rate. The aim of this study was to compare the pregnancy and implantation rates of day 3 and 5 transfers in a prospective randomized manner. Patients with four or more zygotes were randomly allocated on day 1 to either day 3 or 5 transfers. Fertilization was achieved through regular IVF or intracytoplasmic sperm injection. Zygotes were kept in Medicult IVF medium for day 3 transfers and transferred into G1.2 and G2.2 on day 1 and 3 respectively for day 5 transfers. The morphologically best two or three embryos or blastocysts were chosen for transfer in both groups. Overall pregnancy rates per embryo transfer were the same (39%) in day 3 and 5 transfers. Implantation rates were 21 and 24% for day 3 and 5 transfers respectively. The pregnancy and implantation rates for day 5 transfers were significantly affected by the availability of at least one blastocyst to transfer and the number of zygotes. The number of good quality embryos on day 3 also significantly affected pregnancy and implantation rates on day 5 transfers. Multiple gestation rate, number of abortions and ongoing pregnancies were similar in both groups. In conclusion, day 3 and 5 transfer had similar pregnancy, implantation and twinning rates. Currently, day 5 transfers have no advantages over day 3 transfers.

No abstract

The aim of this study was to create reliable models to predict the probability of achieving an ongoing pregnancy during in-vitro fertilization (IVF) treatment: model A, at the start of the first treatment, model B at the time of embryo transfer, and model C, during the second treatment at the end of the first IVF treatment. Prognostic models were created using data from the University Hospital Nijmegen (n = 757) and applied to the data from the Catharina Hospital Eindhoven (n = 432), The Netherlands, to test their predictive performance. The predictions of model B (made at time of embryo transfer) were fairly good (c = 0.672 in the test population). For instance, 93% of the patients who had a predicted probability of achieving an ongoing pregnancy of < 10% did not achieve an ongoing pregnancy. However, the predictions of the other two models (A and C) for Eindhoven were less reliable. The predictive value of model C was fairly high in Nijmegen (c = 0.673). Its poor performance in the test population may be explained partly by differences in effectiveness of the ovulation stimulation protocols and the decision about when to discontinue the cycle. Thus, before using prognostic models at an IVF centre, their reliability at that specific centre should be tested.

As most studies overestimate the cumulative pregnancy rate, a method is proposed to estimate a more realistic cumulative pregnancy rate by taking into account the reasons for an early cessation of treatment with in-vitro fertilization (IVF). Three methods for calculating cumulative pregnancy rates were compared. The first method assumed that those who stopped treatment had no chance at all of pregnancy. The second method, the one used most often, assumed the same probability of pregnancy for those who stopped as for those who continued. The third method assumed that only those who stopped treatment, because of a medical indication, had no chance at all of pregnancy and that the others who stopped had the same probability of pregnancy as those who continued treatment. Data were used from 616 women treated at the University Hospital Nijmegen, Nijmegen, The Netherlands. The cumulative pregnancy rates after five initiated IVF cycles for the three calculation methods were in the ranges 37-51% for the positive pregnancy test result, 33-55% for a clinical pregnancy and 30-56% for an ongoing pregnancy. As expected, the first method underestimated the cumulative pregnancy rate and the second overestimated it. The third method produced the most realistic cumulative pregnancy rates.

Seasonal variation has been found in various reproductive outcomes. As known causes for reducing the rate of success of in-vitro fertilization (IVF) cannot explain all the variation in IVF results, we studied whether the season had any additional explanatory power. The study population consisted of 1126 women who were treated for the first time with IVF at the University Hospital in Nijmegen, The Netherlands, between 1987 and 1993. Only first IVF cycles were analysed. After adjusting for confounding by the age of the woman, type of infertility, indication for IVF and year of aspiration, some seasonal variation was observed in the fertilization rate, embryo quality, pregnancy rate and birth rate.