Poor ovarian response to ovulation stimulating drugs (POR Response):
The term poor response to ovarian stimulation (POR) typically refers to a woman with a reduced ovarian reserve or poor ovarian response to exogenous gonadotropin stimulation. Despite the efforts to optimize the definition of POR, unfortunately there is still limited knowledge about the POR pathophysiology, and the etiology hinders the practical solutions to manage the condition. 
Is this problem frequent?
The occurrence of poor response to ovarian stimulation is not infrequent; the prevalence of poor responders varies in the literature between 9 and 24%. This range is wide as it depends on the definition of a poor responder that individual IVF centers employ. 
Who are poor responders?
There is no universal definition for “poor responders”, although numerous criteria have been proposed by researchers to describe this situation. The number of developed follicles and the number of oocytes retrieved after a standard stimulation protocol are the most important criteria. The proposed quantity varies among authors and ranges from less than three to less than five dominant follicles on the day of hCG administration noted on ultrasound and/or less than three to less than five retrieved oocytes.
What causes low ovarian reserve?
Aging naturally reduces your egg reserves. However, a number of other factors can cause diminished ovarian reserve as:
•    Endometriosis
•    Prior ovarian surgery
•    Chemotherapy
•    Radiation therapy
•    Smoking
•    Pelvic infection
•    Autoimmune disorders
•    Infection Disease
•    Genetic abnormalities such as fragile X syndrome and XO
However, most of the time there’s no apparent cause of the condition.
Symptoms of diminished ovarian reserve
There aren’t many noticeable symptoms of diminished ovarian reserve. However, those with the condition might experience any of the following symptoms:
•    Difficulty getting pregnant
•    Late or absent menstrual periods
•    Shorter menstrual cycles than average, with the average being 28 days
•    Heavy menstrual flow
•    Miscarriage
That said, these symptoms aren’t always present. This is why it’s important to talk to your doctor if you’re having difficulty conceiving.
How to test for low ovarian reserve
It’s important to get fertility testing early if you’re trying to conceive without success or if you have a history of irregular or painful periods, pelvic inflammatory disease, repeated miscarriages, prior cancer treatment, or endometriosis. Early diagnosis means that you have a better chance of successful treatment.
If you’re under 35 years of age, you should see a doctor if you’ve been trying to get to conceive for a year. If you’re over 35, see a doctor after six months. If you’re over 40 and you’re trying to conceive, it’s best to talk to your doctor right away.
Diminished ovarian reserve is diagnosed through a few blood tests that measure follicle stimulating hormone (FSH) and anti-Müllerian hormone (AMH) levels. Both of these hormones play an important role in menstruation and reproduction.
It’s normal for FSH levels to increase and AMH levels to drop as you age, so it’s important to assess these hormone levels against a baseline of your age.