Pro­lactin is a hor­mone that is pro­duced dur­ing preg­nancy. It helps pre­pare the breasts for breast­feed­ing. Some­times, women have a higher level of pro­lactin in their body than usual. This is known as hyper­pro­lactin­aemia. Some lim­ited evid­ence sug­gests that hyper­pro­lactin­aemia may be linked to an increased risk of miscarriage.