What Is In Vitro Fertilization?

In vitro fertilization (IVF), commonly known as “test-tube baby” technology, involves combining eggs and sperm outside the human body. IVF is categorized into three generations: the first generation is referred to as in vitro fertilization–embryo transfer (IVF-ET); the second generation is intracytoplasmic sperm injection (ICSI); and the third generation is preimplantation genetic testing (PGT).

Many patients struggle to distinguish among these three generations—unlike consumer electronics such as smartphones, where each successive generation represents an improvement, this is not the case with IVF techniques. The first-generation approach is the most fundamental and physiologically natural method: patients must understand that, under normal circumstances, first-generation IVF is optimal. In this method, sperm naturally penetrate the egg, achieving fertilization with minimal intervention and thus causing the least trauma.

The second-generation technique (ICSI) is used when sperm count is extremely low or when there is a congenital inability for sperm and egg to fuse spontaneously. A single healthy sperm is selected and directly injected into the egg—a procedure involving deliberate, assisted fertilization.

The third-generation technique (PGT) entails greater procedural complexity and invasiveness. It is employed primarily for couples at risk of transmitting inherited genetic disorders. By genetically screening embryos prior to implantation, PGT enables selection against embryos carrying specific genetic diseases—thereby preventing the birth of affected children and avoiding implantation of affected embryos. While this technology is highly advanced, it inherently involves greater procedural trauma.