They include disorders or processes that decrease the number of eggs in the ovaries, affect the egg development or the ovulation and hence reducing the woman´s fertility. Other factors that have an impact on the egg quality will also affect the chances to conceive.

Age
Fertility decreases with advancing female age.

Women are born with a limited number of eggs in their ovaries. These eggs will be used throughout their life until they reach 50 years old, when 80% of women have run out of eggs and menopause occurs. However 10-15 years prior to menopause there is a significant decrease in the number and quality of the eggs. The risk of having eggs with chromosomal abnormalities rises and even if they are successfully fertilized they will produce embryos less capable of implanting and/or will increase the miscarriage rate. This leads to a gradual decline of woman´s fertility despite having regular menstrual cycles and ovulations.

Several tests may be useful in assessing a woman´s ovarian reserve and thus her fertility potential and her chances to conceive. These tests typically include an ultrasound and a hormonal check-up.

Primary ovarian failure
It includes several disorders where the ovaries fail to produce and develop eggs. Premature ovarian failure is generally associated with an abnormal karyotype, i.e. alterations in the number or structure of chromosomes such as in Turner´s, Swayer´s or Savage´s syndrome.

Investigations carried out to detect this condition typically include a karyotype and a hormonal check-up. Ultrasounds and laparoscopies are also used to diagnose this condition.

Premature ovarian failure
It is defined as an ovarian failure before the age of 40. Some of the causes include hereditary diseases, enzyme alterations, infections, autoimmune disorders or endometriosis which damages wide areas of healthy ovarian tissue.

Chemotherapy, radiotherapy, surgical removal of the ovaries or even smoking may lead to a premature ovarian failure and thus to premature menopause.

Annovulation
When the ovaries do not release eggs to the tubes there is no possibility of conceiving spontaneously. Annovulation occurs when there are alterations in the levels of hormones produced by the ovaries (estradiol, progesterone), by the hypothalamus and the pituitary gland (GnRH, FSH, LH, prolactin, etc.) and by the thyroids (TSH). Other causes of annovulation are a low ovarian reserve or endometriosis in the ovaries.

One of the most common disorders associated with annovulation is the polycystic ovarian syndrome.

The main method for detecting ovulation is a simple blood test to check the progesterone levels.

Hormonal check-ups and ultrasounds will allow the healthcare provider determine the causes of annovulation.

Polycystic ovaries.
Polycystic ovaries are one of the most common causes of infertility and annovulation.

Women with polycystic ovaries have many small follicles in the ovaries and often abnormal FSH and LH levels. They may also present high levels of androgens and glucose and insulin metabolism disorders.

This disorder is frequently associated with irregular periods but no external signs to more severe forms involving lack of periods, enlarged ovaries, excessive hair growth, acne and overweight. We talk about polycystic ovarian syndrome when a woman presents any of these conditions.

The polycystic ovarian syndrome can be detected with an ultrasound examination and a hormonal check-up.  

Endometriosis
Endometriosis occurs when the endometrium (inner layer of the uterus) grows outside the uterus in form of patches that may grow and form cysts.

Endometriosis may lead to a loss of healthy ovarian tissue and therefore a decrease in the ovarian reserve.  This condition may also have an impact on the ovulation and the egg quality. Endometriosis may spread gradually and damage the whole ovarian tissue.

Although endometriosis can be detected with an ultrasound examination, the only definite way to make an accurate diagnosis is by a laparoscopy which allows the surgeon to look inside and remove patches of endometriosis and endometrial cysts. Endometriosis can also be detected during in-vitro fertilization by evaluating the fluid in the follicles.

Egg abnormalities
Other causes of infertility or sterility are genetic or chromosomal abnormalities and alterations in the structure or functionality of the eggs.

Some women that are carriers of chromosomal alterations do not have any health problems or abnormal external signs. Despite having a well-kept ovarian function a large number of eggs are not capable to produce a healthy embryo.

In some cases it may not be possible to detect structural, biochemical or functional disorders in the eggs which may reduce their chances to be fertilized and produce embryos

A karyotype is used to detect chromosomal disorders on both partners. In an in-vitro fertilization cycle it is possible to visualize the eggs appearance, their interaction with the sperm (fertilization) and the development of the embryos. The Preimplantation Genetic Diagnosis (PGD) associated with IVF enable doctors to screen the embryos for chromosomal or genetic abnormalities.

The normal anatomy of the uterus can be studied by ultrasound, Histerosalpingography, laparoscopy and hysteroscopy.

On occasions, there may be structural defects, biochemical or functional oocytes that reduce their ability to be fertilized.