Natural cycle in-vitro fertilization in couples with unexplained infertility: impact of various factors on outcome

This study evaluated outcome in 117 couples with unexplained infertilitywho underwent 162 attempts at natural cycle in-vitro fertilization (NIVF)between 1991 and 1993. An egg was obtained in 138 cycles and a singleembryo was transferred in 89 cycles. There were 16 implantations (fourbiochemical pregnancies, three clinical abortions and nine live births).The implantation rate per embryo was 16/89 (18.0%), which translated into alive birth rate per egg collection of 9/138 (6.5%). The impact factors thatwere assessed included oocyte quality, sperm quality, embryo quality andwoman's age. The outcome measures used were fertilization/inseminated eggand implantation/replaced embryo. All embryo transfers were of singleembryos. We conclude that, in couples with unexplained infertility, outcomefollowing NIVF is affected by both egg and sperm quality and by the age ofthe woman. Embryo quality was independent of the above factors but was alsocritical for successful implantation.