A set of clinical procedures and biomedical laboratory methodologies designed to intervene, optimize, or replace natural biological processes (such as ovulation, sperm capacitation, fertilization, and early embryonic development) to achieve a pregnancy. In clinical practice, they are classified according to complexity into: low complexity (timed intercourse, artificial insemination), where fertilization occurs in vivo; and high complexity (IVF, ICSI, blastocyst transfer), where fertilization and initial embryo culture are performed in vitro.