A condition of pregnancy that usually develops after 20 weeks of pregnancy. The exact causes are unknown however it is thought to be linked to the placenta. Symptoms include severe headaches, blurry vision, and swollen hands, feet, and face. It may also be detected through proteinuria and high blood pressure. It affects around 6% of pregnancies, with severe cases in 1% - 2% of pregnancies (NHS, 2018).