A further option for the application of the cryo-cycle process is the use of what is known as an “artificial cycle” or HRT cycle (HRT: Hormone Replacement Therapy). This requires the woman to initially take only oestrogen, which allows the endometrium to grow. When the optimal build-up of the mucous membrane has been achieved, then orally or vaginally administered progesterone is added. The advantage of this process is the low price and the fact that it does not depend on the condition of the ovaries. The disadvantage is that no follicle, and therefore no corpus luteum, will provide hormones, and oestrogen and progesterone must continue to be taken until approx. week 12 of pregnancy.