A Canadian study has shown that cannabis can have a negative impact on female fertility and the success of IVF treatments. This is the conclusion of a new study that examined the influence of the substance, and its active ingredient THC in particular, on female fertility and artificial insemination. Researchers found that cannabis can negatively affect both because it disrupts the development and stability of the egg cell. During in vitro fertilization (IVF), egg and sperm cells are brought together in a laboratory. In the laboratory, THC led to more errors in chromosome distribution and to a defective egg cell structure.