In the trying to conceive world, most of us are familiar with two important hormone measurements: ovulation tests and pregnancy tests. While these provide valuable information, they only tell part of the story.
Four key fertility hormones make all the difference when it comes to TTC: FSH, estrogen, LH, and progesterone. A more complete understanding of these fabulous four can give you even more insight into your cycle health and ovulation — and ultimately help you get pregnant faster!
But first, a quick cycle recap
Your cycle has two phases: the follicular phase and the luteal phase. The follicular phase lasts from the first day of your period until ovulation. The luteal phase begins after ovulation and ends the day before your period.
The four fertility hormones mentioned above are the chemical messengers that regulate the phases of your cycle. Understanding the balance and interactions among these four hormones can unlock important pieces of the fertility puzzle to help you identify — or rule out — problems early on.
Follicle stimulating hormone (FSH)
Follicle stimulating hormone does exactly as it says — it stimulates your ovaries to grow follicles and prepare to release eggs each cycle. FSH is also a marker of ovarian reserve, or how many eggs you have left. Since women are born with all our eggs already in place (amazing, right?), the ovarian reserve naturally declines over time.
At the beginning of each cycle, during the follicular phase, the brain sends a small amount of FSH to stimulate the ovaries to prepare to release eggs. When you’re young and have many eggs in your ovaries, only a small amount of FSH is needed to stimulate ovulation. Over time as the ovarian reserve goes down, our ovaries have to work harder. This means more FSH is required to stimulate the ovary to do its job.
Elevated FSH levels at the beginning of the cycle can be a sign of low ovarian reserve, which can impact your ability to conceive. You can measure FSH levels via a blood draw from your doctor, in a mail-away kit, or via an at-home urine test from Proov.
Once FSH has done its job, a follicle is ready to release an egg. That’s when the fertility hormone estrogen steps up! We watch for a decline in FSH and a rise in estrogen during the first half of your cycle as an early sign that ovulation may be coming soon.
Estrogen is important for pregnancy because it’s responsible for thickening your uterine lining and maintaining this thickness so that when an embryo is formed, it has a comfy and cozy place to implant.
Studies show that estrogen typically begins to rise in the mid-follicular phase, about 5-7 days before ovulation should occur. Testing estrogen to detect this rise can help you identify the longest possible fertile window — the few days leading up to and the day of ovulation when intercourse is most likely to result in conception.
While an egg can only survive for about 12-24 hours after it’s released, sperm can survive in the female reproductive tract for up to 5 days. This means that timing intercourse around the first sign of a rise in estrogen can help you ensure his sperm is right on time, waiting for your egg!
Estrogen can be measured via a blood draw from your doctor or via a urine-based E1G (estrogen marker) test.
Luteinizing Hormone (LH)
If you’ve used an ovulation test before, then you’re likely familiar with luteinizing hormone. LH is the hormone measured by ovulation tests (also called LH tests) to help you identify your two most fertile days.
Once estrogen reaches a high enough level, your brain gets the signal that an egg is mature and it’s time to ovulate! In turn, your brain sends a surge of LH, which triggers the follicle to release the egg.
An LH surge occurs about 12-48 hours before ovulation, so a positive LH ovulation test helps you identify your two most fertile days. If you haven’t started getting busy yet, now’s the time!
LH is most commonly measured via urine-based LH tests, although it can also be measured via a blood test from your doctor.
After ovulation, the newly empty follicle forms something called the corpus luteum. It’s the corpus luteum’s job to produce progesterone, which is the last player in your four fertility hormone, full-cycle lineup. At this point you’ve entered the luteal phase; the critical timeframe in which embryo implantation may occur.
The presence of progesterone during your luteal phase confirms ovulation took place, but that’s just the beginning of progesterone’s power. This hormone is responsible for stabilizing the already-thickened uterine lining, ensuring it’s “sticky” enough to allow for the best possible chance at implantation and pregnancy.
Progesterone must be adequately elevated during the implantation window (approximately days 7 through 10 after peak fertility) to allow the best possible chance at conception and successful pregnancy.
Low progesterone after ovulation, in contrast, can make it more difficult to get pregnant. In fact, studies show that low progesterone can occur in up to 20% of infertility patients and up to 60% of patients who experience recurrent pregnancy loss.
Progesterone can be measured via a one-time blood test from your doctor or via a urine-based, at-home PdG (progesterone marker) test from Proov. Urine-based PdG tests can provide a more thorough picture, since they allow easy tracking throughout the full implantation window, rather than a snapshot of just one point in time.
When it comes to TTC and fertility hormones, knowledge really is power. The better you understand your hormone balance throughout your cycle, the more quickly you can rule out problems (or solve them if need be), all with the goal of shortening your journey from “trying” to celebrating!