In vitro fertilization (IVF) is the union of egg and sperm artificially in the laboratory in order to obtain a suitable number of embryos to transfer to the uterus and fertilize; thus, women become pregnant. This procedure can solve certain cases of infertility, and is usually resorted to when other assisted reproduction techniques have failed, such as artificial insemination. Insemination of the oocytes can be performed by conventional technique or IVF using intracytoplasmic sperm injection (ICSI), which is used mainly when there is a male sterility factor.