Progesterone has an important part to play in the condition of the wall of your uterus and problems here can make it hard for a fertilised egg to successfully embed itself properly. It can also mean that miscarriage is more likely.

What is progesterone?
Progesterone is the hormone secreted by the ovaries after ovulation each month. It serves to protect the health of the lining of the womb (the endometrium) in readiness for a fertilised egg to implant itself there.
For about ten days (though this time does vary from person to person), it is secreted at levels which maintain the health of the lining. After that the levels of progesterone drop dramatically, allowing the lining of the womb to be cleared away during the menstural period.
If there is not enough progesterone being naturally generated, there is a chance that the womb lining will not be in sufficient health to allow an egg to implant successfully, or that the growing fetus will not be carried through to birth.

Synthetic forms of progesterone are used in medications to control bleeding, and in the birth control pill.

How do I know if I have the right levels of progesterone?
If your GP suspects that you have insufficient levels of progesterone and that this is causing your inability to get successfully concieve or sustain a pregnancy, you can have a blood test. The test needs to be taken at the correct time during your monthly cycle, in order to gauge the levels of the hormone being naturally secreted.

What can be done about it?
There are many drugs on the market now which can be prescribed to better control levels of progesterone in your body. Some are natural progesterone treatments. However, given that progesterone is also used in the composition of birth control pills, you should take any such treatment under medical supervision.
You could also think about your intake of nutrients which can help boost your natural levels of the hormone. Try B6, which is good for the health of your blood, either in foods rich in this vitamin or as a supplement as part of a multi-vitamin. B6 can be found in fortified cereals, beans, meat and fish.
And magnesium is a good mineral to try. You can derive it from green leafy vegetables and nuts, which are rich sources of magnesium.