The Basics of the Female Reproductive System: Understanding Your Cycle
You’d think by the time we’re adults, we’d have a pretty good handle on how our own bodies work - especially something as central as our reproductive cycle. But the truth? Many women were never taught the full picture. I can’t tell you how many times I’ve seen women say, “Wait… you ovulate before your period?” or “How could I get pregnant before my first postpartum period?”
Let’s break it down - step by step, in the order it actually happens - so you can finally connect all the dots.
We’re Born With All Our Eggs
Before we even take our first breath, our bodies have already decided how many eggs we’ll ever have.
-
In the womb: By about 20 weeks of pregnancy, a baby girl has around 6–7 million eggs in her ovaries.
-
At birth: That number drops to about 1–2 million.
-
By puberty: We’re down to about 300,000–500,000 eggs.
-
Over a lifetime, only about 400–500 of those eggs will ever be released during ovulation. The rest naturally break down and are reabsorbed.
Your Menstrual Cycle: More Than “Just a Period”
When people talk about their “cycle,” they often mean their period - but your menstrual cycle is everything from Day 1 of bleeding to the day before your next period starts. The average length is 28 days, but cycles anywhere from 21–35 days can be normal.
Here’s the order things happen in:
1. Follicular Phase (Day 1 to ~Day 14)
This phase begins on the very first day of your period - so yes, the menstrual phase is part of the follicular phase.
-
Days 1–5 (Menstrual Phase): The uterine lining from the previous cycle is shed, resulting in your period. At the same time, follicle-stimulating hormone (FSH) signals your ovaries to start maturing several follicles (each containing an immature egg).
-
After bleeding ends: One follicle becomes dominant, preparing for ovulation, while estrogen levels rise and the uterine lining begins to thicken again.
2. Ovulation (Around Day 14 in a 28-Day Cycle)
This is where many women get mixed up - ovulation happens before your period, not after.
-
A surge in luteinizing hormone (LH) causes the mature egg to be released from the ovary.
-
The egg travels into the fallopian tube and waits about 12–24 hours for sperm.
-
Fertile window: Because sperm can live up to 5 days inside your reproductive tract and the egg can survive 12–24 hours after release, you can get pregnant from sex that happens up to 5 days before and 1–2 days after ovulation.
3. Luteal Phase (After Ovulation)
-
The empty follicle transforms into the corpus luteum, which releases progesterone to prepare the uterine lining for a possible pregnancy.
-
If the egg isn’t fertilized, the corpus luteum breaks down, progesterone drops, and the cycle prepares to start over.
4. Menstruation (Your Period)
Technically, menstruation is the start of a new cycle and the first part of the follicular phase.
-
The drop in progesterone causes the uterine lining to shed, resulting in bleeding.
-
And just like that, a new cycle begins.
Why You Can Get Pregnant Before Your First Period
Many people don’t realize that your very first ovulation happens before your very first period - whether that’s in puberty, postpartum, or after a long break in cycles.
That means children and teens who have not had their first period yet can still get pregnant if they ovulate and have unprotected sex. The same concept applies after having a baby:
Your first postpartum ovulation happens before your first postpartum period.
If you’re sexually active and not using protection or tracking your cycle to avoid your fertile window, you can conceive before ever seeing that first bleed.
-
Breastfeeding can delay ovulation, but it’s not a reliable form of pregnancy prevention.
-
Fertility can return as early as 3–4 weeks postpartum, even without a period.
Ways to Track Your Cycle and Ovulation
Once you understand the order of events, you can start keeping track of your cycle - whether for fertility awareness, trying to conceive, or simply knowing your body better. Here are some of the most common methods:
1. Basal Body Temperature (BBT)
-
Your resting temperature rises slightly after ovulation due to progesterone.
-
Take your temperature every morning before getting up to confirm ovulation has already happened.
2. Cervical Mucus Observation
-
Mucus changes throughout your cycle and is one of the clearest fertility signals:
-
Dry/Sticky: Low fertility (often right after period and post-ovulation)
-
Creamy: Approaching fertility
-
Watery: Fertile
-
Egg White (clear, stretchy, slippery): Peak fertility, ideal for sperm survival and travel
-
-
After ovulation, mucus thickens or dries up again.
3. Ovulation Test Strips (LH Tests)
-
Detect the hormone surge that triggers ovulation, helping you identify your fertile window.
4. Cycle Tracking Apps or Journals
-
Record cycle dates, symptoms, and patterns to spot trends over time.
5. Cervical Position Checks
-
Your cervix changes in height, firmness, and openness during your cycle:
-
Low, firm, closed: Low fertility (feels like the tip of your nose)
-
High, soft, open: Fertile (feels like your lips)
-
-
Check once a day, at the same time, in the same position, for the most accurate comparisons.
-
Best used alongside mucus and BBT tracking.
The Big Picture
Your cycle isn’t just “bleed, recover, bleed again.” It’s a carefully timed hormonal rhythm that starts with your period (which is also the start of your follicular phase), builds toward ovulation - the real main event - and ends with your period if pregnancy doesn’t occur.
When you understand the sequence and learn how to track it, you’re no longer guessing. You can work with your body instead of being surprised by it.