The PCOS Menstrual Cycle:
Understanding Your Hormones
and Ovulation
Maureen Kelly, M.D.
Medical Director
Society Hill Reproductive Medicine
CoFounder
The Wellnest
822 Pine Street, Suite 4B, Philadelphia, PA
What happens in the…
Normal Menstrual Cycle
Overview of the Menstrual
Cycle
The menstrual cycle is a sequence of hormonal events that
leads to ovulation and produces a uterine lining receptive to
implantation of a fertilized egg.
Main Players
• The Brain – hypothalamus and pituitary
• The Ovary - eggs and ovarian hormones
• The Uterus - endometrium
The Pituitary
• The pituitary hormones, FSH and LH, are secreted
at varying levels throughout the cycle.
• This signaling to the ovaries is critical for selection
of a dominant follicle and release of its egg.
Communication Between the
Ovary and the Brain
• As estrogen levels decline at the time of the menses, FSH and
LH are secreted at low levels
• Receptors on ovarian cells respond and ultimately higher levels
of FSH stimulate growth of one follicle out of many
• A surge of LH signals release of the egg
Ultrasound of a normal ovary
Day 1 of Cycle
Prior to Release
Fertilization and Embryo
Development
Ovarian Hormones
• The ovary secretes hormones such as estradiol,
testosterone and progesterone in varying amounts in
response to FSH and LH
• Estradiol builds the layer of the endometrium before
ovulation and progesterone secreted after ovulation
readies the lining for implantation and pregnancy
The Endometrium
Day 1 of Cycle
Time of Ovulation
Menses
• If pregnancy does not occur in a cycle, the ovary
stops producing progesterone
• Withdrawal of progesterone allows an orderly
shedding of the endometrium
• Ovarian hormones are low, the endometrium is thin
and the cycle repeats
What happens in the…
PCOS Menstrual Cycle
Menstrual Symptoms Vary
in Women with PCOS
• Varies from woman to woman
• Can vary from cycle to cycle
• Can vary at different times in a woman’s life
• Ovulation may occur, but if it does, is not consistent
• Menses can be frequent, inconsistent, rare or never
• Bleeding pattern can be scant to heavy and of varied
length
Differences in Ovaries, Eggs & Hormones
Normal Menstrual Cycle
PCOS Menstrual Cycle
Influencers
• Insulin
• Genetics
• Environmental factors, both prenatal and after birth
• Weight
• Diet
• Exercise
The Ovaries
• Can and do secrete their hormones but variation
throughout the cycle does not occur
• Follicles begin development but no dominant follicle
is selected and ovulation does not occur
The Endometrium
• The endometrium thickens in response to estradiol
secretion but progesterone is not secreted
• Shedding of the endometrium, or menses, is not
synchronized
Endometrial Risks of the
Imbalanced Hormones
• Abnormal uterine bleeding
• Hyperplasia
• Endometrial (uterine) cancer
Where the Cycle Breaks Down:
Insulin and Androgens
• Insulin resistance leads to release of higher levels of
insulin
• Ovaries respond to higher insulin levels by secreting
more androgens
• Higher insulin leads to more LH secretion and
androgen production
• Androgens may worsen insulin resistance
• Androgens interfere with ovulation
Optimizing Ovulation and
Conception
• Manage insulin resistance
• Diet
• Weight
• Exercise
• Acupuncture
• Supplements
• Medications
The PCOS Menstrual Cycle:
Understanding Your Hormones
and Ovulation
Maureen Kelly, M.D.
Medical Director
Society Hill Reproductive Medicine
CoFounder
The Wellnest
822 Pine Street, Suite 4B, Philadelphia, PA