In IVF the fallopian tubes are bypassed. The embryo is transferred into the uterus when it has divided to fertilization. After a number of days, this small cluster of cells implants and grows over the next nine months. When IVF was first attempted, its application was limited to women with absent or severely damaged fallopian tubes. Since that time, the indications for IVF have been expanded greatly.
Successes also occur in patients with severe endometriosis and unexplained infertility.
A description of each follows. There are several difficulties in timing ovulation. This added stress may actually postpone ovulation for several days making the situation worse. Secondly, only one egg develops in the natural cycle. If more than one egg were available, a higher chance of success might be accomplished.