There are two clear risks involved with in vitro fertilization. Firstly, women react very differently to the hormonal treatment. For the majority, it is possible to determine the appropriate hormonal dosage according to age and body weight, the appearance of the ovaries in the ultrasound scan, and according to possible previous treatment.

Some of the patients react badly to hormonal treatment and it is possible that the dosages have to be increased accordingly. A small number of patients, however, react very strongly to the administered treatment. In these cases, the ovaries may develop 30-40 follicles, the ovaries consequently become large and swollen and there may be an accumulation of fluid in the abdomen, which causes pain and nausea. This condition is called the ovarian hyperstimulation syndrome (OHSS). Often rest and ensuring adequate fluid intake are sufficient treatment, but in the worst cases hospitalization may be required.

4-cell stage ebryo

A second risk involved with IVF treatment is the increased risk of multiple pregnancies. 1% of all naturally conceived pregnancies are multiple pregnancies whereas the corresponding figure for all IVF-induced pregnancies is 20-30%. Although the majority of multiple pregnancies are carried to term without difficulties, there is always an increased risk of premature birth, low birth weight and complications at birth. A good way to minimise these risks is to transfer only one embryo at a time into the uterine cavity.