Progesterone is known as the “pregnancy hormone,” and there are many reasons for this (at least 15). Lower-than-normal levels of progesterone are associated with increased risk for miscarriage or never becoming pregnant in the first place. Low progesterone can be one of the chief contributing factors that leads to infertility. Along with estrogen, progesterone is an important hormone that must be in balance to achieve and maintain a healthy pregnancy.
Three organs in a woman’s body can produce progesterone: the ovaries, the adrenal glands, and the placenta, which is the organ that nourishes a baby while a woman is pregnant. Progesterone is often one of the synthetic hormones included in oral contraceptives (birth control pills).
Doctors may also prescribe artificial progesterone, which is known as progestin, to treat a number of health conditions. These include absence of periods, endometriosis, breast cancer, and appetite loss related to HIV/AIDS. Low progesterone and high estrogen is associated with an increased risk for endometrial cancer.
There are also natural forms of progesterone available that are harvested from wild yams or soy. However, taking these supplements don’t usually boost overall progesterone levels.
Sometimes low progesterone is a symptom of a non-viable pregnancy, but isn’t the exact reason why a woman has a miscarriage or cannot get pregnant. Low progesterone can be one of several indicators a woman’s body is not working as it should to promote a healthy pregnancy.
While a doctor may prescribe synthetic progesterone in the form of pills, injections, or suppositories, the research is contradictory that this approach is effective in ensuring pregnancy or preventing miscarriage.
15 It Can Affect Intimacy
When a woman enters menopause, her levels of progesterone, estrogen, and testosterone all drop – an effect that can bring her sex drive down. Low levels of these hormones can decrease a woman’s sex drive, affecting her ability to get pregnant. Although there are other ways to get pregnant that don’t involve intercourse (such as in vitro fertilization), sexual desire plays a significant role for many women in conception and becoming a mother.
Progesterone isn’t the only hormone involved in a woman’s sex drive. Others include estrogen as well as testosterone. Estrogen is responsible for stimulating the lubricant that prepares a woman’s body for sex. A lack of estrogen can lead to vaginal dryness that can make sex painful for a woman. Testosterone is also thought to be responsible for increasing a woman’s sex drive.
14 Indicates Poor Ovary Function
The ovaries are responsible for making hormones that support pregnancy. The ovaries also release the eggs that a sperm must fertilize for a woman to become pregnant. If a woman doesn’t have enough progesterone, this could be an indicator her ovaries aren’t working well in the first place.
As a result, a woman may not be able to make healthy levels of hormones as well as eggs that can be fertilized. When a woman is trying to become pregnant, a doctor may test progesterone levels along with hormones such as follicle stimulating hormone (FSH) and anti-Mullerian hormone (AMH) as a measure of potential fertility.
Because progesterone tends to rise and fall throughout a woman’s menstrual cycle, doctors may order the test to determine if or when a woman is ovulating. If a woman doesn’t have the expected progesterone hormone fluctuations, she may not be ovulating regularly. This will affect her ability to become pregnant.
13 It Affects Development Of The Corpus Luteum
A specific part of the ovaries known as the corpus luteum is responsible for releasing progesterone in the body. During the second half of the menstrual cycle (around day 14), the corpus luteum releases progesterone.
This makes the uterine lining more favorable for the implantation of a fertilized egg. Without progesterone, the uterine lining will not support a fertilized egg. If a fertilized egg does not implant in a menstrual cycle, the process of menstruation begins and the cycle starts over.
While some hormones, like testosterone and estrogen, are present in both males and females, progesterone is different because it doesn’t have a role in men. This is likely due to the fact that progesterone is associated so heavily with menstruation and pregnancy.
However, men may be tested for progesterone if a doctor suspects their kidneys aren’t working well because the adrenal glands make progesterone in men.
12 It Helps The Body Tolerate Other DNA
Your body is designed to target “foreign” invaders. Bacteria, viruses, and even the wrong kind of blood cells – your body will attack these and try to keep them from multiplying. Progesterone plays an important role in keeping the body from “attacking” a fetus, even though the fetus has different DNA from the mother. Without progesterone, it’s possible the body could force a miscarriage.
A similar illustration of this effect is known as Rh sensitization. This occurs when a pregnant mother has a “negative” blood type, like A-negative or B-negative, but her baby has a “positive” blood type, the mother’s immune system may start making antibodies to fight off the Rh factors in blood.
While this doesn’t usually cause a problem with a mother’s first pregnancy, the second pregnancy and re-exposure to “positive” blood type can cause a mother’s body to attack the baby’s red blood cells. The results can be anemia, jaundice, and other serious side effects.
11 Keeps The Uterus Relaxed
Your body relies on progesterone during pregnancy to promote muscle relaxation. Without enough progesterone, an expectant mother’s uterus can contract, which could lead to miscarriage. The body relies on progesterone to maintain a relaxed environment.
However, the muscle-relaxing effects of progesterone do have some negative effects associated with pregnancy, including dizziness because the body’s blood vessels are also relaxed.
Progesterone and estrogen often have opposite effects on each other in the body. For example, estrogen can cause uterine contractions. Progesterone causes uterine relaxation. While a woman may not be able to sense this, estrogen can cause the uterus to contract during ovulation. This effect propels the egg toward the uterus.
When progesterone levels start to rise, the contractions stop, making a more likely environment for a fertilized egg to attach. When it’s almost time for a woman to deliver a baby, the amount of progesterone starts to decrease. This has the effect of increasing contractility so a woman can deliver her baby.
10 It Maintains The Uterine Lining
Progesterone is especially important to your pregnancy during the first 8 to 10 weeks. After this time, the placenta starts to produce progesterone instead of the ovaries. When the placenta makes progesterone, a woman’s hormone levels increase even further.
Progesterone maintains the uterine lining after the fertilized egg has implanted. If the body does not make enough progesterone, the lower levels will trigger a shedding of the uterine lining. This is what occurs in menstruation. Without enough progesterone, the lining can shed and the result can be miscarriage.
There is a fine line between a uterine lining that is too thick or too thin. A very thin uterine lining is not optimal for implanting an egg. However, a thick lining (greater than 15 millimeters) also affects the ability for a fertilized egg to successfully implant. A lining of between 8 and 13 millimeters is considered to be a “normal” uterine lining.
9 Promotes The Growth Of Blood Vessels
Progesterone works to nourish the fertilized egg by stimulating the uterine lining to grow new blood vessels. They also are responsible for stimulating the body to release nutrients that nourish the embryo. This acts like a growing baby’s “food” to continue growing and maturing.
While a mother physically eats food, the nutrients are passed to the baby through the placenta and then to the baby. The placenta may be one organ, but it has many functions: kidneys, stomach, and liver. After the baby receives blood flow via the placenta, the blood is then transmitted back to the mother to replenish oxygen and other nutrients.
Clearly, the blood flow that progesterone promotes is vital to promoting blood vessel growth.
During pregnancy, a woman’s blood volume increases by as much as 50 percent. A woman’s body fluids also increase due to additional water retention. This is one of the reasons pregnant women also experience swelling, especially in the ankles and feet.
8 Prepares The Body For Delivery
Progesterone is responsible for relaxing the muscles of the uterus. However, it also has the effect of relaxing and softening the cartilage in the body. This includes those of the pelvic floor. This makes it easier for baby to pass through the birth canal and out into the world. Many pregnant women will notice this effect in other areas, such as increasing swollen and bleeding gums.
When progesterone prepares the body for delivery, a woman may have a more difficult time maintaining her balance. She may also feel very sore and achy. However, this can also be the effect of extra weight.
There are other signs a woman’s body is preparing for birth. This includes that a baby starts to move lower in the pelvis, which can place extra pressure on the pelvis, but reduce the pressure on the lungs. This has the effect of making breathing easier for an expectant mom.
7 It's Needed For Breastfeeding
Progesterone stimulates the growth of maternal breast tissue. It promotes the development of mammary glands that will secrete milk once a baby is born. Without enough progesterone, the mammary glands cannot sufficiently form. Other hormones also contribute to stimulating the growth and development of breasts that can support nursing. These include estrogen and prolactin.
During pregnancy, a woman’s breasts begin to get larger. This is because the hormones in the body are stimulating the growth of ducts and alveoli in the breast that will ultimately produce breastmilk and nourish the baby. Progesterone helps to support breast tissue growth, but it also inhibits the production of breast milk until after a woman delivers a placenta.
After a woman gives birth, the hormone prolactin starts to increase, promoting the production of breast milk. The initial nutrients are called “colostrum,” which is a thick, often yellow-gold like fluid. As a woman’s milk “comes in,” the milk turns more of a yellow-white color.
6 Can Indicate Toxemia (Preeclampsia)
When a woman is in the later stages of her pregnancy, low progesterone levels can be a concerning blood test result. This is because low progesterone levels can indicate toxemia of pregnancy. Another name for this is preeclampsia. Additional symptoms include high blood pressure (greater than 140/90), sudden unexplained swelling, and protein in the urine.
Preeclampsia can lead to life-threatening complications for mother and baby. If a doctor diagnoses a woman with preeclampsia, they will evaluate the severity of her symptoms and the baby’s maturation is determining the next steps for treatment.
If a woman has a history of preeclampsia, obesity, diabetes, kidney disease, or have close family members who had preeclampsia, she is at greater risk for the condition. Women in first-time pregnancies and also those older than age 40 are also at higher risk. A doctor should monitor a woman closely if she has this medical history.
5 Maintains A Regular Cycle
Sufficient levels of progesterone are required for a woman to maintain a regular menstrual cycle. Many women track their ovulation and menstrual cycles to get pregnant. If progesterone levels are low, irregular cycles can result. This affects a woman’s ability to predict when she will be most fertile and therefore potentially get pregnant.
The average woman’s menstrual cycle is usually about 28 days long. However, some women have menstrual cycles that range from 21 to 45 days in teenagers and 21 to 35 days in adults.
Women wishing to get pregnant are most likely to do so during the three days before ovulation and during ovulation itself when the egg leaves and ovary and travels to the fallopian tubes. There is a window of opportunity because a man’s sperm can often continue to remain in the uterine cavity for up to three days when ovulation occurs.
4 Affects Blood Sugar During Pregnancy
One of the symptoms associated with low progesterone in pregnancy is low blood sugar. Low blood sugar can be jeopardizing to baby and mom’s health because the baby cannot get enough nutrients and energy to continue to grow. Blood sugar fluctuations and drops can cause mom to experience significant fatigue that may seem unrelenting at times. In the most severe instances, low blood sugar can cause severe confusion and a coma-like state due to lack of glucose as energy to fuel the body.
A woman’s blood sugar is often an area of concern while she’s pregnant. A condition called gestational diabetes can occur. This results in blood sugar levels being not too high, but instead too low. The effects can be dangerous because excess blood sugar can affect a baby’s health. Women with gestational diabetes tend to have babies that are larger in size as well. Doctors will typically test a woman’s blood sugar levels during pregnancy to ensure gestational diabetes isn’t occurring.
3 Affects Baby’s Adrenal Hormones
A developing fetus uses progesterone to create hormones for the kidneys. These are known as adrenal steroids. These hormones are vital to the formation of the kidneys, which are the major filtration systems of the body. Without enough progesterone, the fetus may have difficulty manufacturing these steroids.
In some instances, babies can experience problems with kidneys and bladders that a doctor can identify before they are even born. An estimated one in 500 births results in an abnormality of the kidneys and urinary tract.
Examples of these conditions include hydronephrosis, which results in enlargement of the kidneys. Another is reflux, which causes urine to back up to the kidneys, which can damage them.
While a mother’s placenta acts as a kidney during pregnancy, it’s important that babies develop their own healthy kidneys so they can grow and produce enough urine after a baby is born. However, there are many ways doctors can treat kidney abnormalities.
2 Indicates Menopause
When a woman goes through menopause and no longer ovulates so she can conceive, her body’s production of progesterone drops. In this way, progesterone is a symptom that a woman is going through a change in her life where she can no longer become pregnant.
If a woman is uncertain of her ability to conceive at an advancing age, low progesterone may be one of the indicators it may be difficult, if not impossible to have a baby.
As more and more women explore the options to have a baby later in life, it’s important to be aware of the impact hormones can have on conception. Women can experience menopause anywhere from ages 40 and 58.
There is also a time period before menopause begins known as perimenopause, which can result in hormone fluctuations. Physical menopause signs can include hot flashes, difficulty sleeping well, and problems with vaginal lubrication.
1 Indicates Ectopic Pregnancy
Low progesterone levels can be an indicator of ectopic pregnancy. This is a pregnancy that causes a fertilized egg to grow and develop in a place other than the uterine cavity. As a result, the fertilized egg can’t grow and develop. A woman may have symptoms as if she has pregnant (such as not getting her period), yet the pregnancy is not a viable one.
Ectopic pregnancy can be a medical emergency. If the embryo continues to develop in a place it shouldn’t, such as the fallopian tubes, abdominal cavity or ovary, severe bleeding can result. Low progesterone levels are one of the indicators doctors use to determine that an ectopic pregnancy is occurring.
Other physical symptoms include mild vaginal bleeding, lower stomach pain, abdominal cramping, and dizziness. If an ectopic pregnancy causes a fallopian tube to rupture, a woman can experience significant bleeding and pain. A woman may even pass out due to this blood loss.