When should women test their Follicle-Stimulating Hormone (FSH) levels when trying to conceive?

When to Test FSH for Pregnancy Conception

FSH testing is recommended for women who are trying to conceive and experiencing menstrual cycle dysfunction, such as irregular cycles or amenorrhea, which may suggest premature ovarian insufficiency (POI). 1

Appropriate Timing for FSH Testing

FSH testing should be performed strategically based on a woman's reproductive status and concerns:

For Women With Regular Menstrual Cycles

• FSH should be measured during the early follicular phase (days 2-5 of the menstrual cycle) 1
• This timing provides the most accurate assessment of baseline ovarian function

For Women With Menstrual Irregularities

• If experiencing amenorrhea: FSH and estradiol can be measured randomly
• If experiencing oligomenorrhea: Measure during early follicular phase (day 2-5) 1
• Testing should be performed after discontinuing oral contraceptives or hormone replacement therapy, ideally after two months without hormonal contraception 1

Specific Indications for FSH Testing

FSH testing is particularly valuable in the following situations:

• Women over 35 years attempting to conceive 2
• Women with irregular menstrual cycles or amenorrhea 1
• Women with symptoms suggesting premature ovarian insufficiency 1
• Women with history of exposure to gonadotoxic treatments (chemotherapy, radiation) 1
• Women with unexplained infertility 3

Interpretation of FSH Results

• Elevated FSH levels (particularly >15 mIU/ml) suggest diminished ovarian reserve 2
• FSH levels should be interpreted alongside other hormonal markers:
  • Estradiol (E2) should be measured concurrently with FSH 4
  • Anti-Müllerian Hormone (AMH) provides complementary information about ovarian reserve 1

Important Considerations and Pitfalls

• A single normal FSH test doesn't guarantee adequate ovarian reserve; values can shift from normal to abnormal range in subsequent cycles, particularly in women of advanced reproductive age 4
• FSH levels can fluctuate between cycles, so repeated testing may be necessary 4
• FSH testing alone has limitations; combining with other markers (AMH, antral follicle count) provides more comprehensive assessment 1
• Very low AMH levels (<0.7 ng/ml) may be associated with higher miscarriage risk 1

When to Refer to a Specialist

Referral to gynecology/reproductive medicine/endocrinology is recommended for:

• Women with menstrual cycle dysfunction suggesting POI 1
• Women with elevated FSH levels 1
• Women without symptoms of POI but who desire assessment of future fertility potential after gonadotoxic treatments 1
• Women over 35 with unexplained infertility 3

By following these guidelines for FSH testing, women can gain valuable insights into their reproductive potential and make informed decisions about family planning and fertility treatments.