This blog is to help you navigate the world of periods and birth control, so instead of the debilitating fear we have associated with a little mishap, or a late period….you’ll know exactly what’s going on in your body. Be empowered, knowledgeable, and in control! Periods are annoying, hormonal imbalance sucks, but I can help you navigate the physiology. Buckle in ladies!
In order to explain how birth control works, we first need to start with periods. You may also want to do some hormone testing if you have any concerns about what is happening in your body.
How Periods Work: Intro to Hormones
All you need to know is that all of your reproductive hormones are under the control of gonadotropin releasing hormone (GnRH). GnRH is released by the hypothalamus in the brain. GnRH controls:
- Follicle stimulating hormone (FSH) – makes those eggs mature
- Luteinizing hormone (LH) – makes the ovary ovulate the egg
- And indirectly: Estrogen and Progesterone – does everything else
The 3 Phases
Follicular Phase & Estrogen (about 14 days)
The follicular phase occurs when your ovaries are working on maturing the “eggs” (aka oocytes or follicles). This happens under the influence of 3 main hormones: estrogen, FSH, and LH. It’s a competition of the fittest. Typically, only one follicle is released by one of your ovaries (you have two of course). When estrogen reaches it’s peak and then falls, you subsequently develop what’s called an “LH surge” this makes one of your ovaries release a follicle and you have officially ovulated! Some girls experience ovulatory pain called mittelschmerz and they can feel which side they ovulated from! Pretty cool eh! When you’re using ovulation strips to plan for pregnancy, it is LH that is detected in the urine. This follicle maturation process takes about 14 days.
While all of this is happening, under the power of the estrogen I mentioned earlier, your uterus is developing a thick lining called the endometrium. We’ll hear more about this later.
Luteal Phase & Progesterone (about another 14 days)
Once you have ovulated, you’re now in the luteal phase. This phase is mostly under the influence of progesterone. The little follicle that was released from the ovary travels into the fallopian tube and waits to be fertilized by a little, mighty sperm. If you’re actively avoiding pregnancy, the follicle is not fertilized and it dies. The follicle only lives for 12-24 hours after ovulation. That’s not very long at all! The mighty sperm however, can live up to 5 days in the uterus waiting for the perfect follicle to fertilize. This means, there’s a chance you can get pregnant 4 days before you ovulate and the day you ovulate. That’s a very narrow window ladies! That is not to say that accidents don’t happen and result in unplanned pregnancies, but I am saying that you DO NOT need to live in fear every day of the month waiting anxiously for your period. If you know your unique body and keep track of when you ovulate then you hold the power!
Now, where was I? When this follicle was released from the ovary it left its fashionable yellow coat behind. This outer coat layer is called the corpus luteum (aka yellow body) and it secretes progesterone! How amazing is that?! Remember that thick lining we were talking about earlier? It is progesterone’s job to make it grow nice and thick so the follicle you released has a comfy spot to live once it has been fertilized. It is also progesterone’s job to keep other sperm away from the uterus after you have ovulated. No tardy sperm allowed! Progesterone blocks late sperm by creating a really thick mucous plug that covers the cervix, which is the opening to the uterus from the vagina.
The corpus luteum, which secretes progesterone, only survives for about 14 days. If the follicle is fertilized, human chorionic gonadotropin (hCG) is created. This is the hormone detected by a pregnancy test. If hCG is present, it tells the corpus luteum to stick around and keep making progesterone to support the endometrial lining. If the follicle is not fertilized, there is no positive feedback to the corpus luteum and it dies. Now there is no more progesterone. It is this progesterone withdrawal that causes bleeding.
Menses (who knows how long this lasts!)
Phew, we made it, what a relief! Now that there’s no progesterone to support the endometrial lining, your body gets rid of the “functional layer” and you have what we loving call a “period”. The length and symptoms of your period depend on ALLLLLL of the hormonal influences in the follicular and luteal phase and vary significantly from girl to girl!
Okay finally the fun stuff: How does birth control work?
The Pill e.g. Alesse
- These pills are called “combination pills” because they contain 2 hormones: synthetic estrogen and synthetic progestin
- These synthetic hormones suppress your body’s natural production of FSH and LH so that you do not ovulate. They essentially trick your hypothalamus and GnRH into thinking that your body has already ovulated so that you don’t!
- Remember how progesterone created a thick mucous preventing sperm from entering the uterus? If you have synthetic progestin in your body at all times you always have this mucus plug, the progestin also changes the endometrial lining so it’s not thick and comfy for a fertilized follicle
The “pill” is 97-99% effective when used correctly
Patches and Rings
- The Nuva Ring, which is vaginally inserted, and Evra patch, which you put on your skin, both work exactly the same way as an oral contraceptive pill
Hormonal IUD e.g. Mirena
- The hormonal IUD only contains synthetic progestin. It creates those same mucous changes as the pill and may prevent ovulation.
- Since it is directly in the uterus, it interferes with the mobility of the follicle and sperm, it produces “hostile” inflammatory prostaglandins, and it affects the enzymes in the endometrium preventing the fertilized follicle from implanting.
The hormonal IUD is 99% effective when used correctly
Copper IUD e.g. Nova-T
- It is also placed directly in the uterus but does not secrete any hormones at all. It owes its effects to the copper
- Like the hormonal IUD, it prevents mobility of the follicle and sperm by creating “hostile” inflammatory prostaglandins. It also affects the enzymes in the endometrium preventing the fertilized follicle from implanting.
The copper IUD is 98% effective when used correctly
And there we have it!
Now you have all the knowledge you need to understand what’s going on in your body and I hope this info alleviates the anxiety associated with…..well, not knowing.
Book an appointment with Dr. Sumner