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 inj ection (IVF/ICSI) was carried out. First, top quality embryo characteristic s 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 o n 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 t o participate of whom 53 produced at least two top quality embryos and were prospectively randomized. In all, 26 single embryo transfers resulted in 1 7 conceptions, 14 clinical and 10 ongoing pregnancies [implantation rate (I R) = 42.3%; ongoing pregnancy rate (OPR) = 38.5%] with one monozygotic twin ; 27 double embryo transfers resulted in 20 ongoing conceptions with six (3 0%) 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 ferti le couples can be achieved after IVF/ICSI, while limiting the dizygotic twi n pregnancy rate to its natural incidence of <1% of all ongoing pregnancies .