Box containing "Clearblue" pregnancy test including instruction leaflet, by Unipath Ltd., Bedford, England, 1985

Confirmation of pregnancy was given in 30 minutes by the ‘Clearblue’ pregnancy test kit. The kit contains two tests. It measures levels of human chorionic gonadotrophin (HCG) in the urine. HCG is a hormone produced by the body during pregnancy. The urine sampler, which looks like a plastic pen, is held in the urine stream. It is then placed in three separate chemical pots for ten minutes each. The urine sampler contains chemicals which react with HCG. The sampler turns blue if the woman is pregnant. This type of test is the forerunner to today’s quicker, more reliable tests. The test was made by Unipath Limited.