The Hormonal Relationship Between LH, PdG, and HCG
Updated May 16, 2023 | By: Premom Team | Medically reviewed by: Heather Frame, BSN, RN
Getting pregnant can, without a doubt, prove a bit more challenging than it seems. Understanding the intricacies of your body's hormonal changes can greatly increase your chances of success. Three key hormones that play vital roles in fertility are luteinizing hormone (LH), pregnanediol glucuronide (PdG), and human chorionic gonadotropin (hCG). In this blog, we’ll explore the hormonal relationship between these hormones and their significance in your fertility journey.
How long does it take to get pregnant?
It's natural to wonder how long it will take to get pregnant, but there is no one-size-fits-all answer. While some couples conceive quickly, it can take others a bit longer. According to a study published in Fertility and Sterility, “A little over 80% of women can expect to become pregnant within 12 months of beginning to try to conceive.” This means that for most women who are trying to get pregnant, it is likely to happen within the first year of trying.
To maximize your chances of getting pregnant faster, understanding the relationship between your fertility hormones, in addition to tracking your fertility, is key!
Understanding the 3 important hormones
Once you discover the intricate roles these hormones play within your body, you’ll feel much more empowered to take charge of your fertility.
Luteinizing hormone (LH)
LH is a hormone secreted by the pituitary gland in the brain and plays a crucial role in regulating the menstrual cycle and ovulation. Just before ovulation, LH levels surge, triggering the release of a mature egg from the ovary. After an LH surge, you can assume ovulation will occur in 24-36 hours. Tracking LH levels through the use of ovulation predictor kits (OPKs) can help pinpoint your fertile window, allowing you to time intercourse accordingly to maximize your chances of pregnancy.
Pregnanediol Glucuronide (PdG)
PdG is a metabolite of progesterone, a hormone produced by the ovaries after ovulation. Progesterone prepares the uterus for implantation and supports early pregnancy. PdG levels can be measured through urine or blood tests and provide insights into whether ovulation has occurred. Elevated PdG levels (above 5ug/mL) indicate that ovulation has occurred and that there is adequate progesterone to support a potential pregnancy. If fertilization does not occur, PdG levels will drop before your next period. Otherwise, levels remain high until your baby’s birthday.
Human chorionic gonadotropin (hCG)
hCG is often referred to as the ‘pregnancy hormone’ because its levels increase significantly after fertilization and implantation. This hormone is secreted by the developing embryo and later by the placenta. It serves as an important marker for confirming pregnancy. Home pregnancy tests work by detecting the presence of hCG in your urine. Blood tests can also measure the precise levels of hCG, helping to monitor the progress of early pregnancy and rule out complications such as ectopic pregnancy or miscarriage.
The charts below show the progression of the three hormones before and after getting pregnant:
Although LH levels will not remain high during pregnancy, note that the chemical makeup of hCG is very similar to that of LH. While pregnancy tests can tell the difference between LH and hCG, ovulation tests cannot. Therefore, an ovulation test may show a false positive result if you are pregnant.
However, it is not recommended to use ovulation tests as a substitute for a pregnancy test. They are not designed to track hCG accurately, and it's just as likely that elevated levels after an LH surge could actually be a second LH surge. Be sure to keep timing intercourse for any LH surge you have.
How to track LH, PdG, and hCG
These methods work best when used together consistently:
- Utilize ovulation predictor kits (OPKs)
- Test LH daily after your period ends
- Observe fertile signs like cervical mucus that resembles raw egg whites
- Confirm ovulation with PdG tests and/or a basal body temperature (BBT) spike
- Test for hCG 12-14 days past ovulation (DPO)
Tracking ovulation through the means of OPKs helps you find your fertile window by detecting an LH surge. Your fertile window is the ONLY time you can get pregnant during your cycle, so aim to time intercourse during this time to maximize your chances of pregnancy!
Charting your BBT daily, in addition to LH testing, is so important because it can confirm ovulation. To efficiently track BBT, you’ll need a basal body temperature thermometer. After sleeping for at least 3 consecutive hours, check your temperature immediately upon waking before getting out of bed. Try to check at the same time each day to ensure accuracy and look for the 0.5-1 degree spike in temperature that should occur within 1-3 days after ovulation.
Along with BBT tracking, PdG testing can also confirm ovulation. You will use these tests after ovulation to watch for a rise in progesterone to confirm ovulation occurred.
Additionally, be on the lookout for fertile cervical mucus. As ovulation approaches, cervical mucus tends to become more thin, clear, and stretchy (like raw egg whites) making it the perfect consistency for traveling sperm.
When you’re 12-14 DPO, you can test for the presence of hCG with your first morning urine. It’s important to wait until this time frame so you get a more accurate result. Some women experience false-negative results when testing too early. The two-week-wait is hard, but hang in there!
This can sound like a lot at first, but once you get the hang of it, it’s so easy and it teaches you a lot about your body. You can make tracking easier with the help of the free Premom app. You’ll be able to track your menstrual cycle, read your ovulation tests, log PdG and hCG results, record your BBT, monitor your cervical mucus, and access many other supportive fertility resources. This makes understanding your body, finding your ovulation day, and timing intercourse easier and can help to improve your chances of getting pregnant!
- The surge in LH triggers ovulation, leading to the release of an egg.
- Following ovulation, PdG levels rise, indicating ovulation has occurred.
- If fertilization occurs, the developing embryo implants in the uterus, leading to the production of hCG.
Lynch, C. D. (2011). How long does it take the average couple to get pregnant? A systematic review of what we know. Fertility and Sterility, 96(3), S115. https://doi.org/10.1016/j.fertnstert.2011.07.451