It’s pretty amazing how much you discover about your body once you start trying to get pregnant, isn’t it? Everything from learning that certain foods can be harm our fertility (ie: too much sugar and caffeine), as well as certain medications and even make-up, TTC can open up a whole new side of your health. Most alarming perhaps is what we learn about our menstrual cycles and how they can be a window into hormonal balance and health.
If you have been trying to get pregnant for several months or longer, at this point you may have accumulated a list of questions and feel left in the dark about what is going on with your body. One common question when pregnancy does not happen in the time frame we thought it would, and especially if experiencing miscarriages, or diagnosed with unexplained infertility, is whether or not low levels of progesterone are to blame.
Below are scientifically backed answers to some common questions you might have regarding progesterone.
What exactly is progesterone?
While it is well known that progesterone is essential for fertility and for sustaining a pregnancy, it is still not yet well understood (1) . Like many hormones in the body, progesterone serves a diverse range of functions; its wide reach has been shown to influence appetite, acne, and hair growth cycles (2) . However, progesterone’s crowning role lies in playing an important part in the menstrual cycle and maintaining the early stages of pregnancy.
Progesterone is a steroid hormone produced by the ovaries and secreted by the corpus luteum, a temporary gland formed inside of the ovary after ovulation. It is a precursor for other important steroid hormones, such as estrogen, cortisol, and testosterone (3) . When progesterone binds to receptors in the uterus, it alters the expression of certain genes in the uterus, causing the uterine lining to thicken in preparation for pregnancy (4) https://europepmc.org/abstract/med/11949965.
How does progesterone influence different phases of the menstrual cycle?
The menstrual cycle can be broken down into three sequential phases: the follicular phase, ovulation, and luteal phase. On the first day of the menstrual cycle, progesterone levels are low. This signals the pituitary gland to produce follicle stimulating hormone (FSH), which helps prepare a a sac in the ovary containing fluid and an egg called a follicle. When the follicle is matured, increased estrogen levels cause a dramatic increase in luteinizing hormone (LH), and the egg is released from the follicle. The fractured follicle, also known as the corpus luteum, produces and secretes progesterone after ovulation in order to thicken the uterine lining (5) . Thickening the endometrium makes it more receptive to implantation of a fertile egg, and also promotes a lasting pregnancy. If the egg is not fertilized, progesterone levels drop, and the thickened uterine lining is shed in preparation for the beginning of another cycle (5).
What are the symptoms of low progesterone levels?
Due to its functions throughout the body, low progesterone can lead to acne, dry skin, foggy thinking, fatigue, and headaches. However, the most marked symptoms are irregular menstrual cycles and infertility. Low progesterone levels prevent the uterine lining from thickening and signal the matured uterine lining to shed prematurely, resulting in a short luteal phase (6). Decreased progesterone is also tied to polycystic ovarian syndrome (PCOS) and mid-cycle spotting (7) . In short, menstrual irregularities and difficulty achieving or maintaining pregnancy may be signs of low progesterone levels. If you are curious about your progesterone levels, it may be beneficial to talk to your doctor about taking a serum progesterone test, which measures the presence of progesterone in your blood (8). In an interview with Dr. Don Aptekar, FACOG MD, however, he explained that there isn’t a great deal of information yet available on progesterone. He says the only way really to tell if a woman has normal progesterone levels is if she gets pregnant and stays pregnant. Otherwise, it’s difficult to tell if progesterone is the underlying cause of infertility or miscarriages. Any single spot progesterone test can give a false indication because in a 90 minute span, your progesterone levels can go up or down, so there may be a false positive or false negative. In other words, in any given moment in time, you may get a different answer.
If you have a regular period, regular cervical mucus patterns, and a luteal phase that lasts 11-17 days, it is highly unlikely that progesterone is the problem if you are having difficulty trying to get pregnant. But whether or not you have regular cycles or irregular cycles, currently the only proof of ovulation AND the ability to support a pregnancy is actually sustaining a pregnancy. Dr. Aptekar says one of the main symptoms of low progesterone is reoccurrence of a chemical pregnancy before implantation is firmly fixed. In this case, he states that there is some scientific evidence that giving progesterone will help maintain the pregnancy. Another known symptom of low progesterone is PMS, but some women respond to progesterone treatment and others do not. So there is no universal agreement on whether progesterone supplementation works or not.
Luteal Phase Defect or Deficiency (LPD) is defined as insufficient progesterone to maintain secretory endometrium and allow for implantation and growth (9). LPD is marked by having a luteal phase less than 11 days, but this alone cannot be used to diagnose LPD. Not all doctors believe LPD exists and reliable diagnostic tests are lacking, so standard for testing does not exist. If LPD is suspected, other conditions may be present such as hypothyroidism, hyperprolactinemia, and myomas.
Prevention of LPD is not possible, but LPD is one of the first suspects if patient has infertility or recurrent miscarriages.
LPD is diagnosed in 3-20% of patients who are infertile, 5-60% of patients with recurrent pregnancy loss. Of women who are fertile, 6-10% have inadequate luteal phase.
LPD can be mistaken for thyroid disease, hyperprolactinemia, polycystic ovarian syndrome.
What are treatment options for low progesterone?
All aspects of progesterone administration, including routes, dose, timing, potential with other drugs, as treatment for infertility is under debate. Treatment depends on the symptoms for low progesterone, and the individual characteristics of different people. Those who are diagnosed with PCOS are commonly prescribed anti-diabetic medication, hormonal birth control, hair growth inhibitor, or progestin therapy to increase levels of progesterone (10) . Conversely, one treatment for people who are diagnosed with an independent case of short luteal phase may be prescribed clomiphene citrate, which causes the ovaries to produce more follicles rather than directly increasing progesterone levels (11) .
Low progesterone levels may be caused by numerous factors and may present differently in each person. Because elements that affect fertility are unique to each individual, it is important to consult with your doctor.
Can you overdose on progesterone ?
Too much progesterone, Dr. Aptekar explains, may risk making your cycle irregular or prolong a nonviable pregnancy. For example, a woman who has a nonviable pregnancy on progesterone supplements may force her body to hold onto the pregnancy until 13 weeks when she would have naturally had a miscarriage at 9 weeks.
Progesterone is intimately tied to biological cycles, and understanding it is important to broadening knowledge about fertility as a whole. Targeting the causes and implications of progesterone imbalance may be useful in adding to the wealth of knowledge and treatments available to boost fertility.