Most pregnancies are uncomplicated. That said, it's helpful to know which serious medical issues are most likely to affect expecting moms. Here's a quick guide to the seven most common pregnancy complications.
Your doctor or midwife will watch for these pregnancy complications (and others) throughout your pregnancy, using physical exams, lab tests, and ultrasounds. Meanwhile, you can help your caregiver by attending all your prenatal appointments and reporting any troubling symptoms.
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 practitioner 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 practitioner suspects a miscarriage, she'll order an ultrasound to see what's going on in your uterus and possibly do a blood test.
Premature labor and birth
If you start having regular contractions that cause your cervix to begin to open (dilate) or thin out (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.
Preterm birth can cause health problems or even be fatal for the baby if it happens too early. The more mature a child is at birth, the more likely he/she is to survive and be healthy.
Preeclampsia is a serious condition that affects about 5 percent of pregnant women. You're diagnosed with preeclampsia if you have high blood pressure and protein in your urine or liver or kidney abnormalities after 20 weeks of pregnancy.
Most expectant mothers 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.
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. According to the March of Dimes, about 4 percent of pregnant women have low levels of amniotic fluid at some point, usually in their third trimester.
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.
Between 2 and 10 percent of expectant mothers 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. But poorly controlled diabetes can have serious consequences for the baby.
For mothers with gestational diabetes, there's a 25 to 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.
When a fertilized egg implants outside the uterus, it's an ectopic pregnancy. One in 50 pregnancies is 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. Since there's no way to transplant an ectopic pregnancy into the uterus, ending the pregnancy is the only option.
If you have placenta previa, your placenta is lying unusually low in your uterus, next to or covering your cervix. Placenta previa isn't usually a problem early in pregnancy. But if the placenta remains dangerously 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 200 deliveries. Women who have placenta previa when they give birth have to deliver by c-section.