Women have an increased vulnerability to depressive disorders during their child-bearing years. Women experience very different physiological changes in gonadal steroids and psychosocial stressors compared to men. This chapter considers hormonal influences on depression and overviews the actions of the gonadal steroids. The gonadal steroid effects are classified into organisational or activational, depending on the duration and timing of the effect. Hormonal treatments for premenstrual dysphoric disorder (PMDD) have encompassed both oestrogen and progesterone. Several studies have now reported that unintentional foetal loss is associated with subsequent risk of depression, post traumatic stress disorder (PTSD) or an exacerbation of obsessive compulsive symptoms. The factors contributing to postnatal depression (PND) include a personal or family history of mood disorder. The use of oestrogen replacement therapy (ERT) is still controversial, particularly with the recent publication of the results of the Women's Mental Health Initiative Randomised Controlled Trial studies.