The thesis primarily focuses on the management of cancers during pregnancy, a condition affecting approximately 1 in 1,000 to 1 in 2,000 pregnancies, which is becoming more prevalent due to an increase in maternal age. It focuses on the diagnosis, management and outcomes of the five most common malignancies: breast, cervical, melanoma, haematological and ovarian cancers. The core dilemma lies in the 'maternal–fetal conflict', whereby optimal oncological treatment for the mother must be balanced against minimising risks to the fetus. This is particularly challenging given that diagnosis is often delayed because cancer symptoms mimic normal pregnancy changes. Treatment protocols must be carefully timed: chemotherapy is strictly contraindicated during the first trimester due to the high risk of congenital malformations (up to 20%), but is considered relatively safe during the second and third trimesters. Radiation therapy and targeted therapies are generally avoided. While maternal remission rates are often similar to those of non-pregnant patients, fetal outcomes are subject for concern, with common complications including high rates of preterm delivery.