A menstrual cycle is, by definition, an ovulatory cycle in which ovulation is the main event and progesterone is made.
Any other kind of bleed is either an anovulatory bleed or a pill-bleed — neither of which are real menstrual cycles. Ovulatory cycles are the only way to make progesterone which is important for general health, not just for making a baby.
An ovulatory menstrual cycle has a follicular phase and a luteal phase
The follicular phase is the pre-ovulatory phase when estradiol is made. The luteal phase is the post-ovulatory phase when progesterone is made. It looks like this.
The follicular phase ranges from seven to 21 days or 32 days for teenagers. It’s the variable part of the menstrual cycle. In contrast, the luteal phase is almost exactly fourteen days (ten to sixteen days) and does not vary.
If you add up the variable (follicular) phase to the fixed (luteal) phase, the duration of a healthy menstrual cycle is anywhere between 21 to 35 days or 45 days for teenagers.
👉Tip: To determine the length of your menstrual cycle, start counting from your first day of proper flow. That’s “day 1.” The days of light spotting that lead up to the proper flow are the final days of the luteal phase of the previous cycle.
Progesterone is the “period-lightening” hormone so if there’s no luteal phase, the result can be a period that’s too heavy or goes on for too long (see below).
An anovulatory cycle has no luteal phase and no progesterone
An anovulatory cycle does not have a luteal phase or progesterone. Instead, it has only a long follicular phase and estrogen and then eventually a breakthrough bleed. It looks like this.
Other names for anovulatory cycles include:
- hormone imbalance
- estrogen and progesterone imbalance
- dysfunctional uterine bleeding
- ovulatory dysfunction
- unopposed estrogen
- breakthrough bleeding
- estrogen dominance (a term I don’t use).
Over time, anovulatory cycles can lead to endometrial thickening, endometrial hyperplasia, or uterine polyps.
Causes of anovulatory cycles
Possible causes of anovulatory cycles include:
- being a teenager
- high prolactin
- hypothalamic amenorrhea or undereating
- recovering from hormonal birth control
- perimenopause or second puberty
- progestin-only birth control including the implant and the hormonal IUD. Read The downside to contraceptives injections and implants.
How do you know if a cycle is an anovulatory cycle?
Signs of an anovulatory cycle
A cycle shorter than 21 days
Counting from “day 1” to “day 1,” a healthy menstrual cycle is anywhere from 21 to 35 days (45 days if you’re a teenager). A cycle shorter than 21 days is almost always an anovulatory cycle.
A cycle longer than 45 days
A cycle longer than 35 days or (45 days for teenagers) is either 1) a very long follicular phase or 2) an anovulatory cycle. It’s not possible to have a luteal phase longer than 16 days except with pregnancy and the rare situation of a corpus luteum cyst.
A bleed that lasts more than seven days
A healthy period lasts two to seven days and loses no more than 80 mL of menstrual fluid over all the days of the period. If you bleed for more than seven days, it’s probably an anovulatory cycle. The flow with an anovulatory bleed can be light, normal, or heavy.
A cycle with no sustained temperature rise
Progesterone causes basal body temperature to rise by half a degree. That’s why healthy ovulation results in a sustained temperature rise during the entire luteal phase. If temperatures don’t rise, it’s a good indication that ovulation did not occur.
👉🏽 Tip: You can also confirm ovulation with a blood test for serum progesterone, but only during the two-week luteal phase. There’s no progesterone during the follicular phase, so if you have a long follicular phase, you’ll have no progesterone for most of your cycle. Read The right way to test progesterone.
How to treat anovulatory cycles
If you’re not ovulating, the solution is to figure out “why not” and treat that.
- If the underlying problem is PCOS, identify your PCOS type and treat that.
- If the underlying problem is undereating, eat more food and carbohydrate for at least six months.
- If the underlying problem is high prolactin, treat that.
Pill-bleeds are not periods
Finally, a bleed on the pill is a withdrawal bleed from contraceptive drugs. There’s no ovulation or even attempt at ovulation so there’s no estradiol or progesterone. It looks like this.
If you do a blood test for estradiol and progesterone while on the pill, you will have almost none.
Ask me in the comments.