Progesterone is a key hormone in the female body. It regulates your menstrual cycle, and prepares your womb each month for pregnancy by thickening the lining of your uterus to accommodate a fertilized egg.  If no fertilized egg shows up, your progesterone levels drop, menstruation returns, and it's business as usual.

But what if your progesterone levels are low all the time? As you would expect, you'll have trouble getting or staying pregnant. Without the thickening of the uterine wall caused by sufficient progesterone, the fertilized egg has no place to go.

Symptoms of low progesterone when you are not pregnant include:

• Low sex drive
• Headaches
• Mood changes, including anxiety or depression
• Irregularity in your menstrual cycle
• Hot flashes

If you are already pregnant and are experiencing any of the following signs, you may have low progesterone:

• Frequent low blood sugar
• Vaginal dryness
• Constant breast tenderness
• Constant fatigue

Progesterone is produced by your ovaries, and production levels will vary over the course of your menstrual cycle, peaking about 7 days before your period. If you suspect your progesterone may be low, see your doctor. She will give you a “PGSN” – a simple blood test that will reveal your progesterone level.

If your progesterone is in fact low, and you are not looking to have a baby, your doctor may do nothing further, or merely prescribe something for the symptoms. If you do intend to have a baby, your doctor is likely to prescribe one or another methods of hormone therapy.

The therapies may be administered topically or via vaginal suppositories. Vaginal rings, which allow for time-release of the hormones, are often favored. There are also oral options available, such as medroxyprogesteron, marketed as Provera.

The hormone therapy will of course ease the symptoms of low progesterone as well. Vaginal dryness, hot flashes and night sweats will be reduced, and your overall mood should improve as well. It may also lower your chances of contracting osteoporosis and diabetes. Administered orally, progesterone therapy can also make it easier for you to sleep.

Downsides? There are a few. Undergoing hormone therapy increases your risk of blood clots, gallbladder problems and stroke. If you are looking to combat a low progesterone condition more holistically, increase your consumption of vitamins B and C, as well as the mineral zinc.

Sources: The Mayo Clinic