- Average of a 28-day cycle in which either a period or pregnancy occur
- Hormones – FSH, LH, estrogen, progesterone
- Organs – brain, ovaries, and uterus
Timeline of the menstrual cycle is as follow:
- Pituitary gland releases FSH and LH, which stimulates follicles in ovaries to mature
- Each follicle contains one ovum – ”egg”
- Maturing follicles secrete estrogen
- When estrogen peaks→ this begins ovulation and the brain is told to ↓ FSH and ↓ LH production
- Ovulation – The most mature ovum bursts out of its follicle and starts traveling towards the uterus via the fallopian tube to potentially become fertilized by a sperm
- In the ovary, the now-empty follicle, the corpus luteum, secretes progesterone
- Stimulates uterine lining (endometrium) to plump with blood and nutrients to prepare for implantation of a fertilized ovum
- If an ovum gets fertilized, it implants itself into the plump wall of the uterus.
- Conception → Pregnancy
- Fertilization occurs when with the sperm and ovum unite
- Fertilized ovum is called a zygote
- Zygote implants approximately 6-8 days after ovulation
- Zygote matures into a blastocyst
- Blastocyst causes the body to produce human chorionic gonadotropin (hCG).
- hCG tells the corpus luteum to continue secreting progesterone
- Maintains the pregnancy until the placenta takes over production, 2-3 months later.
- If the ovum does not get fertilized, the progesterone and estrogen levels drop
- This tells the uterine lining to shed, because it’s not needed to support a pregnancy.
- Blood, tissue, and the ovum are shed and leave the body via the vagina.
- This can take up to 7 days.
- This is a period or menses.
- So what are menstrual cramps?
- The uterus is a muscle, which contracts to release the unused contents.
- Vasoconstriction occurs during these contractions of the uterine muscle.
- This causes temporary oxygen deprivation, which then causes the pain (or dysmenorrhea) associated with menses.
- How long is the cycle?
- The cycle usually occurs every 28 days on average.
- Women are sometimes regular and can count out their cycle and others are irregular and don’t occur at the same time every month
- Ovarian Phases
- Follicular phase
- Before the egg release/Pre-Ovulation
- Starts FSH + LH secretion (follicles are maturing)
- Ovulatory phase
- Egg is released → follicular rupture and release of ovum
- Luteal phase
- Egg has been released
- Corpus luteum secretes progesterone and continues to if pregnancy occurs
- Follicular phase
- Uterine Phases
- Menstrual phase (4-6 days)
- Starts with menstruation → ends with ↑ FSH, starting a new cycle (all if pregnancy did not occur)
- Endometrial tissue is shed, “self cleaning”
- Menstrual phase (4-6 days)
- This is a normal process, no treatment is required
- NSAIDs can be used to manage pain
- Eat complex carbohydrates and avoid high sugar items
- Use contraception if pregnancy is not desired
- Diet and medication education to aid in dysmenorrhea
- Ensure proper hygiene during menses to avoid UTI
We are going to be talking about the menstrual cycle and all the details in hopefully a more understandable way. So to start the main couple of things to know are that it is a recurring cycle, usually 28 days. Ovulation or when the egg is released is around day 14 of the cycle. During the cycle 2 things can happen. You either have a pregnancy or menses start. And the next thing to understand are the hormones involved. The hormones are FSH or Follicle Stimulating Hormone, LH or luteinizing hormone, Estrogen, Progesterone.
Let’s start talking about these hormones and their jobs. So we have a pituitary gland that is going to release FSH and LH. These are going to stimulate the follicles in the ovaries to mature. So what does mature mean? It means they grown, they get bigger! Each follicle is going to contains 1 ovum or egg. As the follicles grow they secrete estrogen. LH surges and Estrogen peaks causing ovulation to happen. So what does this mean? The follicle ruptures and the egg is released. The egg release is ovulation which happens when? Around day 14 of the cycle! So where does the egg go? That egg is going to travel down the fallopian tube in hopes of finding sperm and being fertilized. Fertilization will occur in the tube. So you ask, what now? Now FSH and LH decrease. And do you remember that follicle that ruptured and released the egg? That ruptured follicle will now become the corpus luteum and secrete progesterone. Progesterone is the hormone of pregnancy because it maintains the pregnancy (if there is one). That progesterone is going to get the uterus thick and ready for implantation if fertilization has occurred. Well what if fertilization does not occur? Estrogen and progesterone decrease and the uterine lining (endometrium) is shed. This is menses or period. This is the way the body self cleans. The uterus is like a self cleaning oven. You never need to douche or do anything because a cycle happens every month on its own and cleans it out!
Let’s look at it seperated in the phases. Follicular, ovulatory, and luteal phase.
First the follicular phase. FSH and LH increase which remember stimulates new follicles to mature. One of the follicles becomes the dominant one and produces estrogen. LH also begins to rise.
In the ovulatory phase LH surges and the ovum (egg) is RELEASED from the follicle. This is ovulation which occurs when? Yes, around day 14 of the cycle. The egg starts to travel down the fallopian tube. Estrogen tells the uterus to get ready.
So now we enter the luteal phase. Ovulation has happened so now FSH and LH decrease. Do you remember where the corpus luteum comes from? That ruptured follicle that contained the egg becomes the corpus luteum and secretes progesterone. Progesterone and estrogen tell the uterus to get ready for implantation in case fertilization occurred. So what does get ready mean? It means the uterus is going to start to thicken and plump up with blood supply for possible implantation. If implantation occurs it means we have a pregnancy but without fertilization/implantation there is no pregnancy so the hormone levels all drop and menses occur.
What are women going to feel during this? Typically nothing until menses begins. If menses starts then menstrual cramps will likely occur. This is usually accompanied by some skin breakouts, breast tenderness and mood swings because remember those hormones are fluctuating up and crashing down. The uterus is a muscle so it is going to contract to release the unused contents- this is the cause of the cramps. This is a normal process and no treatment is required however,NSAIDs can be used to manage pain. Diet can be modified to help with pain and complex carbohydrates should be encouraged verses high sugar items. Everyone craves those high sugar items like sweets but this can cause more discomfort! Exercise can also be beneficial.
The patient is pregnant so we consider reproduction as a concept. Comfort is another concept because it is likely that pain will occur for the patient with menses.
So lets review the key points to remember. It is a 28 day cycle with ovulation occurring at around day 14. FSH, LH, Estrogen, and Progesterone are the hormones involved. The cycle ends with either pregnancy or menses.
Make sure you check out the resources attached to this lesson. Now, go out and be your best selves today. And, as always, happy nursing.