Ovarian function and in vitro fertilization (IVF) in Turner syndrome.

Normal numbers of oocytes and ovarian follicles develop to the ovaries during the first half of the fetal life. The oocytes then start gradually disappearing. Abnormal meiotic division due to the lack of a paring X-chromosome has been suggested as the causative factor. A large proportion, 40-50% of Turner girls have at least some pubertal development, and about 10% may undergo menarche. Ovarian follicles have been found in some 40% of teenagers with Turner syndrome. Serum concentrations of antimullerian hormone (AMH) and follicle stimulation hormone (FSH), karyotype with mosaicism or structural chromosomal abnormalities, and spontaneous onset of pubertal development are positive prognostic signs for the presence of oocytes and ovarian function. Spontaneous pregnancies occur in some 2-10% of Turner women, a higher number than estimated earlier. This is probably due to failed identification of the syndrome among Turner women with ovarian function. Premature ovarian failure (POF) at some age can be expected in most of Turner women. FSH-stimulated oocyte retrieval and IVF can be carried out before predicted POF. Counseling not to postpone childbearing unnecessarily is advisable. Collected oocytes can be cryopreserved using vitrification, and stored until a pregnancy is desired. Large number of primordial oocytes within ovarian follicles can be stored in within superficial biopsied pieces of ovarian cortical tissue, for transplantation back to the ovary later on. Oocyte donation is an effective infertility treatment for Turner women who have undergone POF. Adequate hormonal replacement therapy (HRT) before IVF is necessary. Only one embryo at a time should be transferred particularly to these women in order to avoid pregnancy complications. Pregnancies in Turner syndrome women have high risks. Comprehensive health control including MRI of the aorta is recommended already before a planned pregnancy, and aorta has to be followed up by echography at least twice during the pregnancy to evaluate the risk of aortic dissection. Some 30% of Turner women develop hypertension during pregnancy, but this is also common among all oocyte donation pregnancies.