Editor’s note: Any medical advice presented here is expressly the views of the writer and Red Tricycle cannot verify any claims made. Please consult with your healthcare provider about what works best for you.


As the name suggests, progesterone—as in “pro-gestation”—is critical to conception and pregnancy. But we don’t hear much about this super hormone that not only indicates ovulation is occurring properly, but also prepares the uterus to receive a fertilized embryo for implantation.

So why is progesterone so important when trying to conceive? Let’s find out!

Progesterone confirms ovulation.

At the beginning of each menstrual cycle, progesterone levels are relatively low. First, Follicle Stimulating Hormone (FSH) stimulates an ovarian follicle to develop, which causes an egg to mature and increases estrogen production. Then, as estrogen levels rise, FSH production declines and Luteinizing Hormone, or LH, production increases. A spike in LH levels indicates that ovulation or an egg being released from the ovary, is about to occur.

Many ovulation predictor kits measure LH, as the presence of this hormone is “predictive” of ovulation. After ovulation comes the luteal phase, where the corpus luteum produces progesterone. The corpus luteum is the empty follicle from which the egg was released. The presence of progesterone indicates that ovulation has, in fact, occurred, because if no egg is released, there is no empty follicle or corpus luteum, to produce it!

Progesterone stabilizes the uterine lining.

Each month, estrogen is released before ovulation and stimulates the uterine lining to build up. After ovulation, progesterone acts to stabilize the uterine lining so it is at the optimal thickness to support implantation. Progesterone’s role is to prepare the uterine lining for a pregnancy, allowing it to become receptive to the fertilized egg so that it can attach, implant and thrive for the duration of the pregnancy. Ideally, after ovulation, progesterone levels remain high, enabling a fertilized egg to successfully implant.

Progesterone enables a fertilized embryo to implant.

Since progesterone is involved in stabilizing the uterine lining, high levels of progesterone are needed for the embryo to attach in the womb and to maintain the pregnancy. Implantation typically occurs seven to 10 days after ovulation. Up until about the 8th week of pregnancy, the corpus luteum produces progesterone to support the pregnancy. After about the eighth or ninth week of pregnancy, progesterone production is taken over by the placenta and continues to nourish the fetus for the duration of the pregnancy.

Progesterone is needed to maintain pregnancy.

Whether generated from the corpus luteum or the placenta, progesterone levels consistently rise and remain elevated throughout the duration of pregnancy to support a healthy uterine environment for the growing fetus. It has some side benefits too. That pregnancy glow? That’s mighty progesterone at work making the skin appear firmer and brighter!

Tracking progesterone shows the full picture.

While traditional ovulation predictor kits are great for determining the best time for intercourse when trying to conceive, they fail to show the full picture. The menstrual cycle has two distinct phases. The first is the follicular phase, which is comprised of menstruation and the fertile window. This is the time leading up to ovulation. The second is the luteal phase, which is the time after ovulation and is critical for enabling conception and implantation.

Progesterone is the dominant hormone present during the luteal phase. By using ovulation predictor kits to track hormones during the follicular phase and tracking progesterone during the luteal phase, women can understand both halves of their cycle and therefore, the full menstrual picture!

Progesterone plays a critical, direct role in conception and pregnancy, but it plays a peripheral role in other aspects of women’s health related to conception and pregnancy as well. For example, progesterone plays an important role in libido. During ovulation, many women experience their peak in libido, which perfectly matches the fertile window of when you’re most likely to get pregnant.

In the luteal phase, progesterone levels significantly rise and libido typically drops as well. It’s as if high progesterone levels are a stop sign for your body to let you know you’re no longer in the fertile window. It is common for libido to fluctuate throughout the cycle, but what happens if you don’t have any sexual desire at any time during your monthly cycle? Well, this could be a sign of low progesterone. See, for a healthy libido, it is really the balance of estrogen and progesterone that matter the most and if these are out of balance due to low progesterone, it could tank your sex drive.

From confirming ovulation to supporting implantation to helping maintain pregnancy, progesterone is a hard-working hormone that is necessary for so much related to conception, pregnancy and general women’s health. If women are tracking hormones in the first half of the cycle using ovulation predictor kits, adding progesterone to their tracking regimen can help them understand the full menstrual cycle. Knowing about this critical hormone empowers women to ensure their body is ovulating properly and is prepared to receive and support an early pregnancy.

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