Chapter 3 Chunk – Menstrual Cycle & Hormones
(cross-referenced with: CP Chp. 3 PPT, OB Material PDF, Exam Topic List, ATI Maternal
Newborn 12.0 “Reproductive physiology/menstrual cycle” section)
Big Picture: What is the menstrual cycle?
Simple idea
o A monthly cycle that prepares the body for pregnancy.
o Two things are happening at the same time:
Ovarian cycle: what the ovary is doing with the egg.
Endometrial (uterine) cycle: what the uterus lining is doing.
Why you care for the exam
o Shows up in questions about:
Ovulation timing.
Fertility/contraception.
PMS symptoms and NSAIDs.
Hormones like FSH, LH, estrogen, progesterone.
o ATI loves: “Ovulation occurs about 14 days before the start of the next menses.”
Ovarian Cycle – What the ovary is doing
Phases (from your slides and OB material)
o Follicular phase
First half of the cycle (about day 1–14 in a 28-day cycle).
Follicles in the ovary grow under FSH (follicle-stimulating hormone).
One becomes the “dominant” follicle with a maturing egg.
o Ovulation
Triggered by LH surge (luteinizing hormone) from the anterior
pituitary.
Egg is released from the ovary into the fallopian tube.
This is when pregnancy can happen if sperm are around.
o Luteal phase
Last 14 days of the cycle (after ovulation until the next period).
The emptied follicle becomes the corpus luteum.
Corpus luteum secretes progesterone and some estrogen.
If no pregnancy: corpus luteum dies, progesterone drops, period starts.
If pregnancy: hCG from early pregnancy keeps the corpus luteum
alive until placenta takes over hormone production.
Key hormone pattern to remember
o FSH: helps follicles grow.
o LH: big spike causes ovulation.
, o Progesterone: stabilizes and maintains the uterine lining and relaxes smooth
muscle (prevents uterine contractions).
ATI tie-in
o ATI explains that GnRH from the hypothalamus stimulates the anterior
pituitary to release FSH and LH.
o ATI key line they like to test: “Ovulation occurs approximately 14 days before
the next menstrual period.”
Endometrial (Uterine) Cycle – What the lining is doing
From OB Material and CP Chp. 3:
Menstrual phase
o Uterine lining (endometrium) sheds.
o This is what you see as the menstrual bleed.
o Happens because estrogen and progesterone levels drop.
Proliferative phase
o Stimulated by estrogen from growing follicles.
o Endometrium thickens and rebuilds after menses.
o Preparing a cozy lining for a possible embryo.
Secretory phase
o After ovulation, progesterone from the corpus luteum makes lining:
Thick.
Highly vascular.
Nutrient rich.
o This is the best environment for implantation.
Ischemic phase
o Happens only if no pregnancy.
o Progesterone and estrogen fall.
o Spiral arteries constrict.
o Lining becomes ischemic and starts to break down.
o This leads to the next menstrual phase.
Test trap
o Menstrual cycle is not just “bleeding”. Bleeding = one phase.
o Know which hormone dominates each phase.
Hormones – Who does what?
Using your OB material summary + PPTs.
GnRH (gonadotropin-releasing hormone) – Hypothalamus
o Released in pulses.
, o Tells the anterior pituitary to release FSH and LH.
FSH (follicle-stimulating hormone) – Anterior pituitary
o “Follicle starter.”
o Stimulates ovarian follicle growth during the follicular phase.
LH (luteinizing hormone) – Anterior pituitary
o “Ovulation trigger.”
o Sudden LH surge causes ovulation around day 14 in a 28-day cycle.
o Also supports formation of the corpus luteum.
Estrogen – mainly ovaries
o Thickens endometrium during proliferative phase.
o Causes many pregnancy skin changes (melasma, linea nigra, etc., your OB
material mentions this later).
o At high levels, contributes to LH surge.
Progesterone – corpus luteum, then placenta
o “Pregnancy hormone.”
o Maintains uterine lining during secretory phase and early pregnancy.
o Relaxes smooth muscle:
Keeps uterus from contracting too early.
Slows GI tract (constipation in pregnancy).
o Drop in progesterone leads to menstruation.
Prostaglandins
o Increase right before menses.
o Cause uterine cramping and discomfort (PMS).
o NSAIDs (like ibuprofen) help because they block prostaglandin production.
hCG (human chorionic gonadotropin) – early pregnancy
o Produced after implantation.
o Detected in blood and urine pregnancy tests.
o Keeps the corpus luteum alive so it keeps releasing progesterone until placenta
takes over.
ATI connection
o ATI likes to link specific hormones with:
Site of release.
Main action.
What happens when they drop or surge.
Ovulation Timing & Fertility Window
When is ovulation?
o In a regular 28-day cycle, ovulation is roughly day 14.
o The important rule:
Ovulation occurs about 14 days before the next period, not always day
14 of life in every cycle.
Fertility window
o Sperm can live up to about 3–5 days in the female reproductive tract.
, o Egg is best for about 24 hours after ovulation.
o Most fertile days are the few days before ovulation and the day of ovulation.
Exam/NCLEX-style traps
o Question: “Client has a 32-day cycle. When will she likely ovulate?”
Answer: Around day 18 (32 minus 14).
o They might ask:
“Which hormone surges right before ovulation?”
Correct: LH.
“What hormone prepares the endometrium for implantation?”
Correct: Progesterone.
PMS, Cramping, and NSAIDs (from OB Material)
Why PMS hurts
o Before menses, prostaglandins increase.
o This causes:
Uterine contractions.
Cramping.
Headache, mood changes.
Nursing teaching
o NSAIDs (ibuprofen, naproxen):
Block prostaglandin production.
Best if taken before cramps get severe.
o Non-pharm:
Heat to lower abdomen.
Light exercise.
NCLEX-style trap
o If the question asks:
“Which medication helps dysmenorrhea caused by prostaglandins?”
Correct: NSAIDs (not Tylenol, which is not anti-inflammatory).
High-Yield “If You Only Remember One Thing…”
Ovulation happens about 14 days before the next period, not always on calendar day
14.
LH surge = ovulation.
FSH grows the follicle, LH pops the follicle, progesterone maintains the lining.
Estrogen builds the lining, progesterone stabilizes and “fluffs” it.
Drop in estrogen and progesterone causes the period.
Prostaglandins cause cramps; NSAIDs help by blocking them.
(cross-referenced with: CP Chp. 3 PPT, OB Material PDF, Exam Topic List, ATI Maternal
Newborn 12.0 “Reproductive physiology/menstrual cycle” section)
Big Picture: What is the menstrual cycle?
Simple idea
o A monthly cycle that prepares the body for pregnancy.
o Two things are happening at the same time:
Ovarian cycle: what the ovary is doing with the egg.
Endometrial (uterine) cycle: what the uterus lining is doing.
Why you care for the exam
o Shows up in questions about:
Ovulation timing.
Fertility/contraception.
PMS symptoms and NSAIDs.
Hormones like FSH, LH, estrogen, progesterone.
o ATI loves: “Ovulation occurs about 14 days before the start of the next menses.”
Ovarian Cycle – What the ovary is doing
Phases (from your slides and OB material)
o Follicular phase
First half of the cycle (about day 1–14 in a 28-day cycle).
Follicles in the ovary grow under FSH (follicle-stimulating hormone).
One becomes the “dominant” follicle with a maturing egg.
o Ovulation
Triggered by LH surge (luteinizing hormone) from the anterior
pituitary.
Egg is released from the ovary into the fallopian tube.
This is when pregnancy can happen if sperm are around.
o Luteal phase
Last 14 days of the cycle (after ovulation until the next period).
The emptied follicle becomes the corpus luteum.
Corpus luteum secretes progesterone and some estrogen.
If no pregnancy: corpus luteum dies, progesterone drops, period starts.
If pregnancy: hCG from early pregnancy keeps the corpus luteum
alive until placenta takes over hormone production.
Key hormone pattern to remember
o FSH: helps follicles grow.
o LH: big spike causes ovulation.
, o Progesterone: stabilizes and maintains the uterine lining and relaxes smooth
muscle (prevents uterine contractions).
ATI tie-in
o ATI explains that GnRH from the hypothalamus stimulates the anterior
pituitary to release FSH and LH.
o ATI key line they like to test: “Ovulation occurs approximately 14 days before
the next menstrual period.”
Endometrial (Uterine) Cycle – What the lining is doing
From OB Material and CP Chp. 3:
Menstrual phase
o Uterine lining (endometrium) sheds.
o This is what you see as the menstrual bleed.
o Happens because estrogen and progesterone levels drop.
Proliferative phase
o Stimulated by estrogen from growing follicles.
o Endometrium thickens and rebuilds after menses.
o Preparing a cozy lining for a possible embryo.
Secretory phase
o After ovulation, progesterone from the corpus luteum makes lining:
Thick.
Highly vascular.
Nutrient rich.
o This is the best environment for implantation.
Ischemic phase
o Happens only if no pregnancy.
o Progesterone and estrogen fall.
o Spiral arteries constrict.
o Lining becomes ischemic and starts to break down.
o This leads to the next menstrual phase.
Test trap
o Menstrual cycle is not just “bleeding”. Bleeding = one phase.
o Know which hormone dominates each phase.
Hormones – Who does what?
Using your OB material summary + PPTs.
GnRH (gonadotropin-releasing hormone) – Hypothalamus
o Released in pulses.
, o Tells the anterior pituitary to release FSH and LH.
FSH (follicle-stimulating hormone) – Anterior pituitary
o “Follicle starter.”
o Stimulates ovarian follicle growth during the follicular phase.
LH (luteinizing hormone) – Anterior pituitary
o “Ovulation trigger.”
o Sudden LH surge causes ovulation around day 14 in a 28-day cycle.
o Also supports formation of the corpus luteum.
Estrogen – mainly ovaries
o Thickens endometrium during proliferative phase.
o Causes many pregnancy skin changes (melasma, linea nigra, etc., your OB
material mentions this later).
o At high levels, contributes to LH surge.
Progesterone – corpus luteum, then placenta
o “Pregnancy hormone.”
o Maintains uterine lining during secretory phase and early pregnancy.
o Relaxes smooth muscle:
Keeps uterus from contracting too early.
Slows GI tract (constipation in pregnancy).
o Drop in progesterone leads to menstruation.
Prostaglandins
o Increase right before menses.
o Cause uterine cramping and discomfort (PMS).
o NSAIDs (like ibuprofen) help because they block prostaglandin production.
hCG (human chorionic gonadotropin) – early pregnancy
o Produced after implantation.
o Detected in blood and urine pregnancy tests.
o Keeps the corpus luteum alive so it keeps releasing progesterone until placenta
takes over.
ATI connection
o ATI likes to link specific hormones with:
Site of release.
Main action.
What happens when they drop or surge.
Ovulation Timing & Fertility Window
When is ovulation?
o In a regular 28-day cycle, ovulation is roughly day 14.
o The important rule:
Ovulation occurs about 14 days before the next period, not always day
14 of life in every cycle.
Fertility window
o Sperm can live up to about 3–5 days in the female reproductive tract.
, o Egg is best for about 24 hours after ovulation.
o Most fertile days are the few days before ovulation and the day of ovulation.
Exam/NCLEX-style traps
o Question: “Client has a 32-day cycle. When will she likely ovulate?”
Answer: Around day 18 (32 minus 14).
o They might ask:
“Which hormone surges right before ovulation?”
Correct: LH.
“What hormone prepares the endometrium for implantation?”
Correct: Progesterone.
PMS, Cramping, and NSAIDs (from OB Material)
Why PMS hurts
o Before menses, prostaglandins increase.
o This causes:
Uterine contractions.
Cramping.
Headache, mood changes.
Nursing teaching
o NSAIDs (ibuprofen, naproxen):
Block prostaglandin production.
Best if taken before cramps get severe.
o Non-pharm:
Heat to lower abdomen.
Light exercise.
NCLEX-style trap
o If the question asks:
“Which medication helps dysmenorrhea caused by prostaglandins?”
Correct: NSAIDs (not Tylenol, which is not anti-inflammatory).
High-Yield “If You Only Remember One Thing…”
Ovulation happens about 14 days before the next period, not always on calendar day
14.
LH surge = ovulation.
FSH grows the follicle, LH pops the follicle, progesterone maintains the lining.
Estrogen builds the lining, progesterone stabilizes and “fluffs” it.
Drop in estrogen and progesterone causes the period.
Prostaglandins cause cramps; NSAIDs help by blocking them.
