As you approach the final trimester of pregnancy, both excitement and anticipation build. The last few weeks before your baby arrives involve not just preparing the nursery and packing your hospital bag but also undergoing essential screening tests. These tests are designed to check your health and ensure a safe delivery for both you and your baby. At Summit Women’s & Wellness Medical Group in Rancho Cucamonga, CA, Dr. Renee Obey helps expecting mothers understand these crucial screenings so they feel empowered and informed.
This guide will walk you through the primary third-trimester tests, explaining what they’re for, what to expect, and why they’re necessary for a healthy delivery.
Group B Streptococcus (GBS) Screening
One of the most common screenings in the third trimester is for Group B Streptococcus (GBS). GBS is a bacteria that can naturally occur in the digestive and lower genital tracts. While it doesn’t typically cause illness in adults, GBS can be dangerous if passed to the baby during childbirth.
Why is GBS Screening Important?
About 10-30% of pregnant women test positive for GBS. Although most newborns exposed to GBS do not develop complications, a few may experience severe infections such as meningitis or pneumonia. Screening for GBS is a standard practice to prevent these rare but serious outcomes.
What to Expect
The GBS test is generally performed between the 35th and 37th week of pregnancy. Dr. Obey will take a simple swab of the vaginal and rectal areas, which is then tested in a lab. If the results are positive, you will likely be given antibiotics during labor to reduce the chance of passing the bacteria to your baby.
Non-Stress Test (NST)
As the due date approaches, some expectant mothers may be asked to undergo a Non-Stress Test (NST) to monitor the baby’s well-being. The NST measures the baby’s heart rate in response to movement, providing insights into how well the baby is receiving oxygen.
Why is NST Important?
NST is especially important if you have certain medical conditions (like diabetes or hypertension), are carrying multiples, or have noticed a decrease in fetal movements. This test helps Dr. Obey ensure your baby is healthy and determine whether early intervention is necessary.
What to Expect
During an NST, you’ll be asked to lie down, and a monitor will be placed on your abdomen to record the baby’s heartbeat. The test typically takes around 20-30 minutes, and you may be asked to press a button whenever you feel the baby move. If the heart rate increases with movement, it’s a positive sign. However, a lack of response doesn’t necessarily mean there’s a problem; sometimes, the baby may simply be asleep. If needed, further testing can be arranged.
Biophysical Profile (BPP)
The Biophysical Profile (BPP) is another tool to assess the baby’s health, particularly if there are concerns about growth, or if you’re past your due date. The BPP combines an ultrasound with an NST to evaluate the baby’s movements, muscle tone, and amniotic fluid level.
Why is BPP Important?
A BPP can provide a more comprehensive picture of your baby’s health and help identify any need for immediate intervention. By assessing the amniotic fluid levels, Dr. Obey can determine if the baby has enough cushioning, which is vital for their safety during delivery.
What to Expect
The BPP is a non-invasive procedure where you’ll undergo an ultrasound while Dr. Obey monitors the baby’s movement, breathing, and overall activity. The BPP is scored, with each factor receiving a score of 0 or 2. A total score of 8-10 is generally considered normal, while lower scores may indicate the need for closer monitoring or potential early delivery.
Amniocentesis (if necessary)
While amniocentesis is often associated with the second trimester, it may sometimes be performed in the third trimester. This test involves drawing a small amount of amniotic fluid to detect infections or assess lung maturity if an early delivery is anticipated.
Why is Amniocentesis Important?
Amniocentesis in the third trimester may be recommended if you have an infection, or if your baby is at risk of respiratory issues. The test can help determine if your baby’s lungs are developed enough for delivery.
What to Expect
Amniocentesis is performed under ultrasound guidance to ensure safety. A small needle is inserted into the uterus through the abdomen to collect amniotic fluid. While this test does carry slight risks, Dr. Obey will discuss any potential concerns beforehand. The procedure is generally quick, and results are typically available within a few days.
Glucose Tolerance Test (if needed)
Although the Glucose Tolerance Test (GTT) is commonly performed in the second trimester, some women may need to repeat it in the third trimester. This test is particularly important if you are at risk of gestational diabetes, which can impact both your health and your baby’s.
Why is the GTT Important?
Gestational diabetes can lead to complications, including higher birth weights, premature delivery, and increased risk of cesarean section. Monitoring glucose levels helps ensure that any blood sugar issues are managed for a smoother delivery process.
What to Expect
The GTT requires fasting, followed by drinking a glucose solution and undergoing a series of blood tests to measure your body’s response. If high glucose levels are detected, Dr. Obey will discuss dietary adjustments or other management strategies to keep your pregnancy as healthy as possible.
Doppler Ultrasound for High-Risk Pregnancies
For certain high-risk pregnancies, Dr. Obey may recommend a Doppler ultrasound to measure blood flow in the umbilical cord, placenta, or baby’s brain. This test is especially useful for women with conditions like preeclampsia or growth restrictions.
Why is Doppler Ultrasound Important?
The Doppler ultrasound provides critical information about whether your baby is receiving adequate oxygen and nutrients. If blood flow issues are detected, closer monitoring or early delivery might be considered.
What to Expect
The Doppler ultrasound is similar to a standard ultrasound, except it measures blood flow using sound waves. It’s a painless, non-invasive test that takes only a few minutes and offers vital insights into the baby’s health.
Planning for a Healthy Delivery
Third-trimester screening tests play a pivotal role in preparing for a healthy delivery. They offer peace of mind and, when necessary, give you and Dr. Renee Obey at Summit Women’s & Wellness Medical Group an opportunity to take action before labor begins. By staying informed and proactive, you’re setting yourself up for a smoother birth experience and a healthier start for your newborn.
Sources:
- Martin, J. A., Hamilton, B. E., Osterman, M. J., & Driscoll, A. K. (2020). Births: Final Data for 2018. National Vital Statistics Reports.
- MedlinePlus. (2023). Group B Strep Infection and Pregnancy. National Library of Medicine.
- ACOG. (2022). Prenatal Screening Tests. American College of Obstetricians and Gynecologists.
