9 pregnancy complications to be aware of

Studies show that about 8 percent of pregnant women will experience serious complications. It's scary to contemplate, but know that your doctor or midwife will watch closely for issues throughout your pregnancy. And you can help lower your risk by attending all your prenatal visits and reporting any troubling pregnancy symptoms.

Here's a quick guide to the most common pregnancy complications.

1. Miscarriage

Miscarriage is the loss of a pregnancy in the first 20 weeks. About 10 to 20 percent of known pregnancies end in miscarriage, and more than 80 percent of miscarriages happen before 12 weeks. Most first-trimester miscarriages are believed to be caused by chromosomal abnormalities in the fertilized egg that keep the embryo from developing.

Vaginal spotting or bleeding is usually the first sign, so call your healthcare provider right away if you notice it (although it's not uncommon to spot or bleed in early pregnancy even if you're not miscarrying). If your provider suspects a miscarriage, they'll order an ultrasound to see what's going on in your uterus and possibly do a blood test.

Learn more about miscarriage.

2. Ectopic pregnancy

When a fertilized egg implants outside the uterus, it's an ectopic pregnancy. About 1 to 2 percent of pregnancies are ectopic. Because the vast majority of ectopic pregnancies occur in a fallopian tube, they're often called "tubal" pregnancies.

It's important to catch this type of pregnancy early because the growing embryo could rupture your fallopian tube and cause internal bleeding that can be fatal. There's no way to transplant an ectopic pregnancy into the uterus, and the embryo can't survive outside the placental site.

Learn more about ectopic pregnancy.

3. Gestational diabetes

About 6 to 9 percent of expectant mothers in the United States develop this type of diabetes. That might not sound like many, but the condition is common enough – and serious enough – that pregnant women routinely get a glucose screening between 24 and 28 weeks to test for it.

If you develop gestational diabetes, you'll be closely monitored by your healthcare provider. Most women are able to keep their blood sugar levels under control with diet and exercise and deliver healthy babies, while others will require medications, most commonly insulin. Poorly controlled diabetes can have serious consequences for a mom and her baby.

For mothers with gestational diabetes, there's a 50 percent chance of developing type-2 diabetes later in life, though this risk can be significantly reduced by maintaining a healthy weight and lifestyle. Women who are a normal weight have less than a 25 percent risk, while women who have obesity have a 50 to 75 percent risk of developing type-2 diabetes after having gestational diabetes.

Read more about gestational diabetes.

4. Preeclampsia and gestational hypertension

Preeclampsia and gestational hypertension are two types of high blood pressure you can get in pregnancy.

Preeclampsia is a serious condition that affects about 5 to 8 percent of pregnant women (though the incidence is about twice as high in first pregnancies). You're diagnosed with preeclampsia if you have high blood pressure and protein in your urine after 20 weeks of pregnancy.

Most expecting moms who get preeclampsia develop mild symptoms near their due date, and they and their babies do fine with proper care. But it can progress quickly, and severe preeclampsia can affect many organs and cause serious or even life-threatening problems. Women whose preeclampsia is severe or getting worse need to deliver early.

More than 4 percent of pregnant women in the United States develop gestational hypertension, and it's also more common in first pregnancies. Gestational hypertension is diagnosed if you develop high blood pressure after 20 weeks of pregnancy but don't have protein in your urine or other symptoms of preeclampsia.

Read more about preeclampsia.

Read more about gestational hypertension.

5. Placental abruption

This condition happens when the placenta separates partially or completely before your baby is born. It can happen before or during labor, and it can be dangerous for both you and your baby. Placental abruption happens in about one in 100 pregnancies, most commonly in the third trimester, though it can occur any time after 20 weeks.

Depending on when the abruption happens and how major it is, you may need to deliver immediately by C-section if your baby isn't getting enough oxygen.

Read more about placental abruption.

6. Placenta previa

If you have placenta previa, your placenta is lying unusually low in your uterus, next to or covering your cervical opening. If the placenta remains low as your pregnancy progresses, it can cause bleeding, which can lead to other complications and may require you to deliver early.

The location of your placenta will be checked during your midpregnancy ultrasound exam, but only a small percentage of women who have placenta previa in midpregnancy still have it when they deliver their baby. Placenta previa is present in up to 1 in 250 deliveries. Women who have placenta previa when they give birth have to deliver by C-section.

Read more about placenta previa.

7. Low amniotic fluid (oligohydramnios)

The amniotic sac fills with fluid that protects and supports your developing baby. When there's too little fluid, it's called oligohydramnios. It can happen any time in pregnancy, but it's most common in pregnancies that reach full term. About 11 percent of women between 40 and 41.5 weeks gestation have too little amniotic fluid.

If this happens to you, your caregiver will follow your pregnancy closely to be sure your baby continues to grow normally. If you're near the end of your pregnancy, labor will be induced.

Read more about low amniotic fluid.

8. Depression

One in seven pregnant women suffer from depression, a mood disorder that can leave you feeling sad and hopeless for weeks or months. It's also common for women to develop the first signs of postpartum depression (PPD) during pregnancy.

If untreated, depression during pregnancy is linked to preterm labor and low birth weight. There are treatment options that are safe during pregnancy, including psychotherapy and/or medication. Be sure to seek help (and referrals as needed) from your medical provider.

Read more about depression during pregnancy.

Read more about postpartum depression.

9. Premature labor and birth

If you start having regular contractions that cause your cervix to begin to open and/or thin out (dilate and efface) before you reach 37 weeks of pregnancy, you're in preterm or premature labor. When a baby is delivered before 37 weeks, it's called a preterm birth and the baby is considered premature. About 10 percent of babies in the United States are born prematurely.

Preterm birth can cause health problems or even be fatal for babies if it happens too early. The more mature a child is at birth, the more likely they are to survive and be healthy.

Read more about preterm labor.

Learn more:

• Learn which pregnancy symptoms you should never ignore.
• Find out about infections and how they can affect your pregnancy.