Recent years have seen a notable increase in the number of breast cancer diagnoses among women who have not fulfilled their maternity plans before the disease. Cytotoxic drugs (chemotherapy), used in the treatment of breast cancer patients, cause varying degrees of damage to the ovaries. The expected favorable effect of gonadoliberin analogues on the preservation of fertility has not been confirmed in clinical trials, and these drugs are currently not recommended for therapy. It is only the development of cryobiology and assisted reproduction techniques that make it possible to preserve the reproductive potential. The safety of the mother and the baby after breast cancer treatment is a separate issue. The available data indicate that both, pregnancy and breast-feeding are safe for the mother and the baby. However, the majority of findings come from retrospective studies covering small sample size and excluding the heterogeneity of both, cancer cells and patient clinical data.