In Vitro Fertilization With Preimplantation Genetic Screening

Abstract

Both in vitro fertilization (IVF) and preimplantation genetic screening are being increasingly used, the latter for women of advanced maternal age. Observational studies show that, when screening is added to IVF, implantation rates increase but rates of ongoing pregnancies do not. Some researchers believe that preimplantation genetic screening of cleavage-stage embryos for aneuploidies may make IVF more effective. The present multicenter, randomized, double blind, controlled trial compared 3 cycles of IVF with embryo selection based either on preimplantation genetic screening or on the morphologic features of the embryo. Of the 408 participants, all women ranging in age from 35 through 41 years, 206 were assigned to preimplantation genetic screening. Screening accompanied 434 of 836 cycles of IVF. Screening began 3 days after follicular aspiration by biopsying a single blastomere on all embryos having 4 or more blastomeres. Compared with control women, those having preimplantation genetic screening had a significantly lower rate of ongoing pregnancy (25% vs. 37%). The rate ratio was 0.69, with a 95% confidence interval (CI) of 0.51–0.93. Biochemical and clinical pregnancy rates also were significantly lower in the screened group, but there was no significant difference in rates of miscarriage. Women assigned to genetic screening had a significantly lower rate of live births than control subjects (24% vs. 35%). The rate ratio was 0.68, with a 95% CI of 0.50–0.92. Not only did preimplantation genetic screening fail to increase rates of ongoing pregnancy and live births following IVF in this population of older women, but observed rates were lower than in control (unscreened) women. At present, preimplantation genetic screening should not be routinely performed in women of advanced maternal age who undergo IVF. It is not clear whether different results would be obtained in women with indications for genetic screening other than advanced maternal age.