Follicular growth and hormonal contraception in the adolescence and the perimenopause

The early phase of adolescence is defined from the first menstrual bleeding (menarche) until the first ovulatory cycle. At the menarche 300 - 400,000 oocytes are available, which either undergo ovulation or atresia. In the last decades, the age of menarche decreased and the percentage of sexually active adolescents increased. In addition, due to compliance problems adolescents are at high risk of failure rates for most methods of contraception. Therefore, the number of unintended pregnancies in this group of population is markedly high, and special regard should be focussed on contraception counseling in this period of life. During the perimenopausal phase, a reduction in ovarian size and number of ovarian follicles occur as main morphological changes in the gonads. This gradual disturbance of the functional integrity of the hypothalamic-pituitary-ovarian system is reflected in bleeding irregularities caused by the development of corpus luteum insufficiency, prolongation of follicular maturation, anovulation, and finally amenorrhea. With age over 35, adverse effects of contraceptive pills are markedly increased.