Advances in Managing High-Risk Pregnancy
Prenatal tests and treatments benefit mother and child.
If you’re pregnant or considering a pregnancy, you’ve likely wondered what you can do to help ensure you have a healthy baby. Obstetricians and perinatologists—specialists in high-risk pregnancy—can assess your risks and provide you with the latest developments in maternal-fetal medicine.
Your team will help you have the best outcome for your pregnancy—a healthy, full-term baby.
New Testing Options
Prenatal genetic testing is an important option to consider for women at increased risk because of age or prior history. The goal of this testing is to identify babies who are affected by chromosomal abnormalities—an extra chromosome, a condition called Trisomy. These abnormalities are present in a fetus from conception and can cause a variety of problems, including mental and physical disabilities—the most common and well-known is Trisomy 21, which causes Down syndrome.
Years ago, this testing could only be done by an invasive method known as amniocentesis (done at 16-21 weeks) or chorionic villus sampling (CVS, done at 10-14 weeks). These tests are still available and are very accurate methods of assessing the baby’s chromosomes. But they carry a small risk of miscarriage, which some parents are unwilling to take.
Other tests, using blood testing—known as maternal serum screening—combined with ultrasound measurement of the thickness of a fold on the fetus neck—known as the nuchal fold—were also used to identify babies at greater risk for Trisomy.
Today parents have the option of a more sensitive, non-invasive prenatal diagnosis done after ten weeks. Women identified at risk for having a child with Trisomy—either due to age or elevated risk on maternal serum screening—are offered this new blood test. This test uses technology that can evaluate fetal DNA, found in small amounts in the mother’s blood.
The new test can diagnose babies with Down syndrome (Trisomy 21), Edward syndrome (Trisomy 18) and Patau syndrome (Trisomy 13) as well as sex-linked syndromes or abnormalities of the X and Y chromosomes. This test is both safer than the invasive amniocentesis or CVS and more sensitive than maternal serum screening and nuchal fold ultrasounds.
Preventing Premature Delivery
Another important contributing factor to having a healthy baby is achieving a full-term pregnancy. A normal pregnancy lasts about 40 weeks, and a baby born before 37 weeks is considered preterm and may be at risk. Approximately half a million babies are born prematurely in the United States every year.
Being born prematurely can cause a variety of medical problems in a newborn because the baby’s lungs, brain and gut are not fully developed until the final weeks of a pregnancy. As obstetricians, our goal is to help our patients avoid preterm birth by identifying who is at risk and doing what we can to lower that risk.
Risk factors for preterm labor include a history of having previously delivered a premature baby, having a multiple pregnancy (twins, triplets, etc.) and having had surgery on your cervix or cervical problems in the past.
For women who’ve had a preterm birth, progesterone injections during a later pregnancy can lower her risk of having another. Progesterone is a hormone normally made by the mother’s body during the pregnancy. Although it’s not known how these injections reduce the mother’s risk, this is the first medication that’s truly made a difference in decreasing preterm birth rates.
Many women have preterm contractions or other symptoms of preterm labor—such as pressure, change in discharge and even cervical dilation—and it can be challenging for the obstetrician to determine who is truly at risk for premature delivery. Fortunately, recent medical advances help identify who’s really at risk and needs treatment.
Tests for Preterm Labor
In the past, when a woman arrived at her OB’s office or at the hospital with signs of preterm labor, she was monitored for contractions and change in cervical dilation over time. Now, two new tests help doctors make a more definitive diagnosis.
The first is a test of the vaginal fluid for fetal fibronectin. This protein can be present in vaginal fluid at any time after 22 weeks but is more likely present if the mother is going into labor. If the protein is not present, then preterm delivery is very unlikely. This test has helped reduce the number of women over-treated for premature labor and alleviates worry that over-treatment is happening.
The second test uses ultrasound to measure the length of the cervix. Ultrasound can be used during weeks 16 through 26 to see if the pregnancy is likely to last until full term. At this time, the cervix should be longer than 2.5 cm. When the cervix is shorter, the risk of preterm delivery is higher. Interventions such as progesterone injections and even a cervical cerclage (stitches to tighten the cervix) can be used to help prevent premature labor. The cervical-length test is most useful because it can identify a sign of preterm labor even before a woman has begun to feel symptoms.
Whether it’s to determine if your baby is free of chromosomal abnormalities or to help your pregnancy get to full term, these medical advances are now available at our area’s state-of-the-art health centers. Talk to your obstetrician about what testing and treatment may benefit you and your baby.
Elizabeth Louka, M.D., and Srijaya Soujanya Nalla, M.D., are OB/GYNs with Delaware Valley Women’s Care, part of the Crozer-Keystone Health Network. They see patients in Drexel Hill and Newtown Square. For more information, 610-394-4710; CrozerKeystone.org.
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