REDUCING THE RISK OF MULTIPLE GESTATIONS IN IN VITRO FERTILIZATION
By transferring 2 embryos.
Aberdeen, United Kingdom
The transfer of only 2 embryos does not reduce the possibility of pregnancy and reduces the risk of multiple pregnancies.
New England Journal of Medicine 339573-577 aSNC
The authors have no conflict of interest
In in vitro fertilization, the transfer of more than 2 embryos increases the risk of multiple births, according to researchers from Aberdeen Maternity Hospital. Templeton and Morris came to this conclusion after analyzing the factors that influence the development of embryos. multiple gestations when using this fertilization technique. Using information obtained from the UK Human Embryology and Fertilization Authority database, they studied factors associated with elevated risk of multiple pregnancies in 25,240 women. The factors analyzed included age, duration and reason for infertility, previous fertilizations, previous live births, number of fertilized eggs, and number of embryos transferred. The results were evaluated according to the rates of birth and multiple births as a consequence of the embryo transfer. The chances of pregnancy and multiple gestations decreased significantly in the presence of factors such as older age, infertility due to pathology in the tubes, more than 4 in vitro fertilization attempts and duration of infertility. The effect of the number of embryos transferred was analyzed in relation to the number of fertilized eggs. The transfer of 2 embryos reduced the possibility of pregnancy, single or multiple. However, the transfer of 3 embryos did not increase the probability of pregnancy either, but it did increase the chances of twin and triplet gestations. At all ages, the chances of pregnancy were not higher when 3 embryos were transferred instead of 2, however, the possibility of multiple births did increase in the first case. In women aged 30, 35 and 40 years, pregnancy and multiple gestation rates were related to the number of fertilized eggs and the number of embryos transferred.In this evaluation the authors found that increased embryo transfer results in higher multiple birth rates, without necessarily improving the rate of positive results from in vitro fertilization. The consequences of these results are clear, the transfer of 2 embryos does not reduce the chances of pregnancy, but it does reduce the chances of multiple pregnancies.