The Normal Fertility Cycle in a Nutshell
Hi! I’m Dr. Jenna, and welcome to my practice, where I feel thrilled to be supporting women and their amazing bodies. Since I recently shifted my focus to fertility and women's hormones, you'll be hearing a lot about that in the coming month.
The normal female cycle may not seem like the sexiest topic, but the basics of your menstrual cycle - the language, the vocabulary, and the different phases - encompass essential knowledge which facilitates both fertility wellness and, frankly, balance and harmony for your hormones. Happy hormones = happy humans. So let’s dive in!
Your Female Menstrual Cycle begins at the start of your first menses during puberty. For the first time, your body prepares an egg for fertilization, and your uterus for carrying a baby. This process continues monthly until menopause, when your body transitions to stop menstruating.
Lengths of menses and the menstrual cycle can vary broadly, with a normal period ranging anywhere from 3-7 days, and a menstrual cycle from 21-35 days. Our bodies are beautifully dynamic, and rhythms are impacted by factors such as age, genetics, nutrition, stress, other hormones and endocrine organs like the thyroid, gut health, and exogenous hormones (aka birth control and environmental chemicals toxins). When we think about what “healthy” looks like for you, what’s most important is that it’s relatively regular from month to month.
The female cycle is divided into the Follicular Phase which begins with menses, and the Luteal Phase, which begins at ovulation. An elegantly orchestrated series of hormone-initiated events kick off the start and end of each phase.
Here’s what happens during each cycle:
Follicular Phase and Menstruation: Days 1-14
The first day of your cycle is marked by the first day of full flow bleeding, day 1 of your period. This first phase extends up until ovulation. During this time, the pituitary gland in the brain produces a hormone called Follicle Stimulating Hormone, or FSH, which signals to the ovaries, “Hey! It’s time to begin maturing eggs into follicles!” Each egg then gets matured into a single follicle. These egg-containing follicles begin to make estrogen, which signals to the uterus, “Build up your lining and get ready to receive an ovulated egg and support new life!” Estrogen also signals production of even more FSH, signaling the follicles to grow, which keep producing more estrogen. Around Day 15, estrogen reaches a threshold.
Luteal Phase and Ovulation: Days 15-28
The estrogen threshold triggers the pituitary gland to produce a dramatic spike in luteinizing hormone (LH), aka the “LH surge” which kicks off the Luteal Phase. This signals one of the mature follicles to ovulate: to rupture and release the egg it has carried. Some signs of ovulation include:
thin, stretchy, clear, and slippery cervical fluid, consistency of an egg white
some women notice a one-sided pain or discomfort in their lower abdomen where the ovaries are located
libido may increase as the body says “It’s time to make a baby!”
basal body temperature will drop in some women
The released egg travels through the fallopian tube on into the uterus. Here, if sperm is present, the egg is fertilized; if not, the uterus lining continues to build.
Back in the ovary, the ruptured follicle becomes the corpus l