Homologous intrauterine insemination (IUI) is an assisted reproductive technique where the partner's sperm is introduced directly into the woman's uterus. This procedure is typically used in cases of mild infertility, both male and female, or in cases where the cause of infertility is unexplained. IUI increases the chances of conception by placing sperm closer to the natural site of fertilization, where, after ovulation, it is possible to find the egg, thus optimizing the fertilization process naturally.

Second-level in vitro fertilization techniques (FIVET and ICSI) and third-level techniques (surgical sperm retrieval) using homologous gametes represent advanced Assisted Reproductive Technologies where both the eggs and sperm come from the couple. Among the main techniques are traditional in vitro fertilization (FIVET) and intracytoplasmic sperm injection (ICSI), which are applied when first-level treatments, such as intrauterine insemination, have not been successful or when the cause of infertility makes first-level treatments impossible. The embryos obtained in vitro are transferred to the uterus, either fresh or after thawing.

Heterologous in vitro fertilization using donated eggs is an effective solution to overcome conception difficulties related to the woman's advanced age or issues related to the quantity and quality of the available eggs. This technique is used when ovarian reserve is compromised or when the patient’s eggs are unable to ensure a positive treatment outcome. The donor eggs are selected according to strict medical criteria and possess optimal characteristics both in terms of genetic quality and vitality, which significantly increases the chances of achieving a pregnancy.

The main advantage of this technique lies in the fact that donor eggs come from young, fertile women, whose reproductive potential is significantly higher than that of a patient with reduced ovarian reserve. This translates into higher success rates, with a greater likelihood of obtaining high-quality embryos ready to be transferred into the recipient's uterus.