The beginning of the female cycle is the first day of the menstruation. The first cycle phase lasts approximately two weeks. During this period the egg grows and after ovulation lies at the end of the fallopian tube and waits for the semen. The second cycle phase, also called the proliferation phase, is important to prepare the uterine mucosa for the nidation.
In all these complex interactions between the egg maturation, ovulation and nidation, some problems can occur which prevent pregnancy from taking place.
Causes for the dysfunction of the egg maturation could be among others a hormone imbalance or a dysfunction of the thyroid gland. Under or overweight and stress may also influence the egg maturation and fertility.