I have many friends who have had miscarriages, some of whom had more than one before they successfully had children. It is common, but that doesn't lessen the pain. Many women don't tell a lot of people about it because people tend to say very insensitive things, and that makes a painful situation worse.

When you discover you're pregnant or you're wishing you are, thoughts of miscarriage are common. However, worry won't prevent a miscarriage--it only sucks the joy out of being pregnant.

Miscarriage is loss of the pregnancy before 24 weeks. After that, technically, it is a "stillbirth," but I usually hear later losses referred to as miscarriages, probably because "stillbirth" is such a horrible term.

Most miscarriages occur before you even know you're pregnant. The development of the embryo is very complex and implantation is tricky, and errors occur. Late periods are often a sign of an early miscarriage. If you know when you ovulated because you used ovulation predictor kits, and your period is more than 14 days after ovulation, you probably had an early miscarriage. Often these periods are heavier than usual. If you've already tested positive for pregnancy, you have crossed one milestone.

The rest of miscarriages typically occur before 14 weeks of pregnancy. Again, faulty development of the embryo is likely the reason, and there is nothing you can do about this. There are many steps in development, and any error will result in a miscarriage. Later losses, such as at 6 months, are often due to problems with the placenta or the mother, such as placenta abruptio or clotting disorders.

Is there anything you can look for? Bleeding at any time in pregnancy is potentially a problem. You should call your doctor if you have any bleeding. However, many doctors will not rush you in in the first trimester because there is nothing they can do to stop a miscarriage. It seems hard-hearted, I agree, but that is the reality that the doctors live with.

Loss of pregnancy symptoms, such as breast tenderness, is tricky. Your breasts are not tender the entire pregnancy. The tenderness comes and goes, usually most tender at the beginning and the end of pregnancy. If you feel less tender one day, it could mean that the progesterone is falling, or it could mean nothing and tomorrow you'll feel tender again. Experts debate the importance of progesterone levels in pregnancy since successful pregnancies have occurred in the presence of low progesterone.

Cramps are also confusing because they are common in early pregnancy, such as at implantation. Also, as the uterus stretches, cramps occur. If they are severe, that is not usually a reassuring sign.

I have heard that some women just felt something was wrong, and then a few days later, bleeding started. I believe in the power of intuition. At the same time, it can be such an emotionally charged time that it is easy to over-analyze every physical feeling. What can you do? Get in the best health you can before you even attempt pregnancy, take your prenatal vitamins, and avoid smoking, alcohol and caffeine. And try to enjoy the hope that this month is your month!