Understanding Fertility

Why test?

Many women become pregnant easily, but for others this may require some assistance. ZRT’s Fertility Profile can help if you:

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Blood Spot:

  • Estradiol (E2)
  • Progesterone (Pg)
  • Testosterone (T)
  • Sex Hormone Binding Globulin (SHBG)
  • DHEA-S (DS)
  • Thyroid Stimulating Hormone (TSH)
  • Free Triiodothyronine (fT3)
  • Free Thryoxine (fT4)
  • Thyroid Peroxidase Antibody (TPO)
  • Follicle Stimulating Hormone (FSH)
  • Luteinizing Hormone (LH)


  • Diurnal Cortisol (CX4)

  • Have hormonal symptoms
  • Have been trying to conceive for more than six months
  • Are in your mid 30's or older
  • Have had difficulty sustaining pregnancy in the past
  • Know infertility runs in your family
  • Want to assess your fertility status

Common hormone-related causes of female infertility:

Low Progesterone

Progesterone produced by the ovaries during the second half of
the menstrual cycle is essential for preparing the uterus for
implantation of the fertilized egg. In some patients, ovulation and
fertilization of the egg may occur normally but progesterone is
not produced in sufficient amounts to sustain pregnancy.

Thyroid Disorders

Low levels of the thyroid hormones fT3 and fT4 may prevent
ovulation, which can be indicated by no periods or irregular
cycles. Autoimmune thyroid issues, resulting in elevated levels
of antibodies to the thyroid gland can increase the risk of

PCOS (Polycystic Ovary Syndrome)

PCOS affects between 6% and 15% of women during their reproductive years. PCOS is a common cause of ovulation problems, weight issues, and miscarriages. Once PCOS is recognized and treated, many women are able to become pregnant.

Low Egg Reserve

Declining egg production is the primary reason for the age-related decline in fertility. A low egg reserve can also be caused by premature ovarian failure.


Stress affects ovulation due to its effect on the endocrine system. High cortisol can inhibit ovulation, where low cortisol can affect the immune changes necessary for implantation to occur. Stress may also lead to the development of endometriosis, which is found in more than 50% of women with unexplained infertility.



Fertility Brochure    Infertility Sample Report

Additional resources and information

View an insightful webinar that explains the importance of hormone testing and fertility.