Pregnancy is full of uncomfortable rites of passage. Morning sickness... mood swings... chugging a big cup of syrupy sweet liquid, waiting an hour and then having your blood drawn...

Not familiar with that last one? It's the glucose challenge test, which is used to screen for gestational diabetes. You'll probably experience it yourself sometime between week 24 and week 28 of your pregnancy.

What's gestational diabetes,you ask? Gestational diabetes, or GDM, is a type of diabetes that happens to a woman who did not have diabetes before she got pregnant.

It's actually pretty common, affecting up to 9% of moms-to-be.

Like other types of diabetes, GDM affects how your body uses blood sugar, also known as glucose. Unlike other types of diabetes, however, GDM goes away as soon as you give birth.

GDM is typically diagnosed late in the second trimester or early on in the third. It starts with the one-hour glucose tolerance test. That's where you drink the syrupy sweet liquid and then have your blood drawn one hour later.

If your blood sugar is high, you'll have to come back another day and repeat the test. But this time, your blood will be drawn every 60 minutes for three hours.

So, what causes GDM? Here's what science tells us.

Glucose flows through your blood stream to provide energy to your cells. Insulin is a hormone that allows glucose to be absorbed by your cells.

When you get pregnant, your placenta starts producing estrogen, progesterone and other hormones. These pregnancy hormones can block insulin from reaching the receptors on your cells. This reduces the amount of glucose that your cells can absorb. Since the glucose isn't being absorbed by your cells, it remains in your blood stream. This increases your blood sugar level.

Enter: gestational diabetes.

We don't know for sure why some women get GDM and others don't. But we do know there are certain risk factors. Some of the most common ones are being overweight or older than 35, having a personal or family history of GDM, or having slightly elevated blood sugar levels before getting pregnant.

The good news is that most moms with GDM won't experience any symptoms. Even better news? GDM is one of the most easily managed pregnancy complications. And as long as you follow your treatment plan, you'll have a normal pregnancy and a healthy baby.

A GDM treatment plan typically has two parts: lifestyle changes and some extra monitoring with your doctor. Those lifestyle changes involve what you eat and how much you move. Your doctor might refer you to a registered dietitian or a diabetes educator to help you come up with a meal plan that suits your tastes and your budget. You can count on it being full of fruits, vegetables, whole grains and lean protein.

One potential complication of GDM is an unusually large baby, so you'll have more ultrasounds and other tests to check your little one's growth. You'll also have to check your blood sugar in the morning and after every meal to be sure that you're staying within a healthy range.

Gestational diabetes can sound scary, but remember that both you and your little one will stay perfectly healthy with the help of monitoring and treatment from your doctor.