Pregnancy tests you might need (and why they’re important)

Receiving a health screening, no matter what it is, can be nerve-racking. But when it comes to tests that monitor the health of you and your baby during a pregnancy, those nerves can skyrocket.   

But if you’re overwhelmed by the number of tests your prenatal doctor tells you that you need, try not to be. Many of them are routinely given to every pregnant woman—and for good reason.

“Some testing is oriented towards the mother, like screening for certain chronic diseases or genetic mutations that may affect her not only during this pregnancy, but during future pregnancies,” says Meagan Haynes, M.D., an OB-GYN at Yale Medicine in New Haven, Connecticut. And other tests can detect infections and other underlying health conditions that can lead to preterm labor or the transmission of certain diseases through the placenta or via the birth, she says.

The bottom line: All these tests will help keep both you and your baby as safe as possible throughout your pregnancy. Here are some of the most common tests you’ll receive.

Urine test

What it is: A sample of your urine, which is sent to a lab to look for possible infections and other pregnancy-related complications.

When it’s done: At each prenatal visit.

Why it’s done: “Urine samples help screen for certain diseases, like gestational diabetes, preeclampsia, urinary tract infections, and asymptomatic bacteria in the urine,” says Dr. Haynes.

STI screening

What it is: Screening for sexually transmitted infections (STIs) like chlamydia and gonorrhea (which can be detected by taking a swab from the cervix), and syphilis, HIV, hepatitis C, and hepatitis B (which can be detected with a blood test).

When it’s done: Your first prenatal visit.

Why it’s done: Some STIs can cause complications to the pregnancy, whereas others can cause complications to the baby after birth. “Certain infections, like chlamydia, are easily treated,” says Dr. Haynes. “But if they aren’t detected, they can cause significant problems for the mother in the future, including pelvic pain and infertility, or for the child, like blindness.” Other STIs, like HIV, are treated with an antiviral medication (much like a chronic disease), she continues, and with the right treatment, the chances of transmitting the virus to the baby are extremely low.

Rh factor blood test

What it is: A blood test that detects whether your blood has Rh factor, a protein that’s found on red blood cells.

When it’s done: First prenatal visit. If you are Rh-negative, another test will be done between weeks 28 and 29.

Why it’s done: Most people have Rh factor, meaning they’re Rh-positive. But if you’re Rh-negative and your baby is Rh-positive, your body will mistake your baby’s blood as a foreign substance, and create antibodies to defend itself. While these antibodies typically don’t cause a problem during the pregnancy (usually the baby is born before the antibodies are developed), they can cross the placenta during subsequent pregnancies and attack those baby’s red blood cells.

Glucose tolerance test

What it is: This is a measurement of your blood sugar levels. You’ll drink a glucose-containing liquid, and then have your blood drawn either once or twice. If the results indicate that your blood sugar levels are high, you’ll likely have a follow-up test that could be similar to the first one.

When it’s done: Between 24 and 28 weeks, as you can become less sensitive to insulin as your pregnancy progresses, says Dr. Haynes. If you had gestational diabetes during a previous pregnancy, however, it may be done earlier.

Why it’s done: The test screens women for gestational diabetes, a type of high blood sugar that’s first diagnosed during pregnancy. If the test shows that you do have gestational diabetes, your doctor will probably monitor your pregnancy more closely—including with nonstress tests, which can track your baby’s heart rate—as well as help you lower your blood sugar levels with diet changes, lifestyle tweaks, or medication.

Group B Strep

What it is: A swab of your vagina and rectum that can detect the presence of group B Streptococcus (GBS), a type of bacteria that commonly resides in the gastrointestinal and genital tracts.

When it’s done: This is usually done between 36 and 38 weeks.

Why it’s done: GBS isn’t usually harmful, but if you’re currently harboring the bacteria, there’s a small chance that you could pass it to your baby during birth, who could then develop an infection or complication like pneumonia. If you do test positive for GBS, your doctors will give you an antibiotic during labor, which will help prevent your child from becoming infected.

Stay on the lookout for warning signs and complications
Some women are at risk for complications during pregnancy, so it’s important to recognize that something may be wrong and when to seek medical care. Know the warning signs and call your doctor immediately if you experience any of the following symptoms.
 
Preeclampsia/Eclampsia

• Persistent headaches
• Blurry vision, spots, or flashes of light
• Nausea or vomiting
• Swelling in your hands or feet, progressing to the face and eyelids
• Sudden weight gain of two pounds per week or six pounds per month
• Pain in the upper right side of your abdomen
• Shortness of breath
• Seizures 

Preterm labor

• Six to eight tightening instances or contractions in an hour
• Leaking of fluid
• Any vaginal bleeding
• Low back pain, abdominal cramps, or pressure in your pelvis
• Diarrhea 

Blood clot

• Chest pain
• Difficulty breathing or shortness of breath
• A leg that is red, swollen, warm, or tender to the touch

If you experience any of these symptoms, contact your doctor immediately. If you feel your life may be in danger, call 911.