Different options for prenatal screenings may be offered to pregnant women, often leaving moms-to-be with questions about what the tests are looking for and when they should be performed.
The time before a baby's birth can be both exciting and anxiety-producing for the mother-to-be. As she awaits the baby's arrival, there is much to prepare, many choices to make and for some women, worries about their unborn child's health.
To address these concerns, prenatal screenings are often performed to look for birth defects or other prenatal health conditions. Who opts for these tests, which kind of tests they choose, when the tests are performed and why can vary widely.
Following the Progress of Pregnancy
According to the Mayo Clinic, "Prenatal screening tests can identify whether your baby is more likely to have certain conditions — but they usually can't make a definitive diagnosis."
These prenatal screenings can involve things like blood tests, ultra sounds, and examination for issues with the baby's chromosomes. If there is evidence of a potential problem, diagnostic tests may be performed in some cases.
The types of tests pregnant women may opt for vary as their pregnancy develops. First trimester screening, performed during weeks 11 and 13 of pregnancy, is routine and typically involves a maternal blood test and ultrasound.
According to the Centers for Disease Control and Prevention (CDC), the blood test is a routine sample of the mother's blood, which looks for evidence of chromosomal issues, like Down syndrome. In Down syndrome, the child has an extra copy of one chromosome, with mental and physical effects.
If levels of two proteins, human chorionic gonadotropin (hCG) and pregnancy associated plasma protein A (PAPP-A), are high in the maternal blood test, it could hint that a chromosomal disorder is present.
"The ultrasound for the first trimester screen looks for extra fluid behind the baby’s neck," explained the CDC. "If there is increased fluid found on the ultrasound, there could be a chromosomal disorder or heart defect in the baby."
According to March of Dimes (MOD), a non-profit organization focusing on the health of mothers and babies, a cystic fibrosis carrier screening can also be performed on both the mother and the father during the first trimester. This tests to see if either parent carries the gene that can cause cystic fibrosis, a genetic condition that often affects the lungs and digestive organs.
As the pregnancy continues, second trimester screenings may be executed during weeks 15 and 20 of the pregnancy. These screenings usually involve a maternal serum screening and another ultrasound to look for additional types of birth defects.
The maternal serum screen is another blood test of the mother, looking for additional evidence of risk for chromosomal issues, heart defects and for evidence of neural tube defects, which effect the baby's spine, brain or spinal cord. This round of screenings involves measuring levels of four proteins - alpha-fetoprotein (AFP), estriol, hCG and inhibin A, which can provide evidence of these issues.
The second trimester ultrasound, called an anomaly ultrasound, looks for structural issues in the way the baby is developing and checks up on the size of the unborn child.
A Personal Decision to Dive Deeper
It is at this point that personal questions regarding moving forward may come up for many women.
"If the result of a screening test is abnormal, doctors usually offer further diagnostic tests to determine if birth defects or other possible problems with the baby are present," explained the CDC.
The CDC explained that diagnostic tests are also commonly offered to women who are considered as having a higher risk pregnancy. This can include women aged 35 or older and those with certain chronic health conditions like diabetes, high blood pressure, epilepsy or lupus.
Women using certain medications known to cause complications during pregnancy and women who have had a birth defect issue during a previous pregnancy might also be offered these diagnostic tests.
These diagnostic tests might include chorionic villus sampling (CVS), usually performed between weeks 10 and 12. This tests also looks for potential genetic issues like Down syndrome, Tay-Sachs disease or hemophilia, by examining cells gathered from the placenta surrounding the baby.
CVS can either be performed by gathering a sample through the cervix or by using a thin, long needle through the abdomen. The procedure carries various risks, including risk for infection and, according to the Mayo Clinic, an overall risk of miscarriage in one of 100 cases.
Another diagnostic test called amniocentesis is sometimes performed between weeks 15 and 18, also to search for genetic issues like Down syndrome or Tay-Sachs. This test collects a sample of the amniotic fluid around the baby through a needle inserted into the mother's abdomen.
Amniocentesis also measures for several proteins produced by the baby, including alpha-fetoprotein (AFP) and acetylcholinesterase (AChE). High AFP levels might indicate defects involving the abdominal wall or neural tube defects, like spina bifida, in which the spinal cord does not fully develop, or anencephaly, in which the brain and skull do not fully form. If is detected, it suggests that there is an opening in the baby's neural tube.
As mentioned, these diagnostic screenings can include more invasive and potentially risky procedures. And before it even gets to the point of diagnostic screening, expectant mothers may question what will come from information potentially gained from any prenatal screenings.
The Mayo Clinic urged pregnant women to ask themselves a number of questions in regard to prenatal screening, including what they will do with information learned as a result of prenatal screening.
"Normal results can ease your anxiety," explained the Mayo Clinic. "However, if prenatal testing indicates that your baby might have a birth defect, you could be faced with wrenching decisions — such as whether to continue the pregnancy. On the other hand, you might welcome the opportunity to plan for your baby's care in advance."
Some problems that these tests may uncover can be treated during pregnancy, some may need to be treated immediately after birth and some may not require clear, pressing plans of action, said the Mayo Clinic, which also pointed out that these tests are not perfect, and that errors can occur.
"Prenatal screening tests for fetal abnormalities are optional," the Mayo Clinic stressed. "It's important to make an informed decision about prenatal testing, especially if you're screening for fetal conditions that can't be treated."
The Mayo Clinic suggested that expectant mothers discuss the risks and benefits of prenatal screening with their doctor, or with a genetic counselor. These counselors can provide a more in-depth understanding of any unique risks present in individual pregnancies.
In an interview with dailyRx News, Andre F. Hall, MD, of Birth and Women's Care in Fayetteville, North Carolina, explained that he routinely offers initial maternal blood tests screening for birth defects to all of his pregnant patients, though some decline the testing.
"The most common reasons I hear for declining this test is that in the event of a positive test, the patient would not consider pregnancy termination as an option or that she does not want to know if the baby she is carrying is abnormal, especially since there is nothing we can do to change it," explained Dr. Hall.
"Others opt to have the test, not that they would necessarily consider a pregnancy termination, but rather that they would want to know to give themselves and their family time to adjust to the news," said Dr. Hall.
A Healthy Birth
CDC reminded women that while not all birth defects can be prevented or planned for, steps can be taken to help keep both mother and baby healthy until birth.
These steps include avoiding drugs, alcohol and tobacco, discussing the use of any medications with a physician, discussing vaccinations with a physician, maintaining a healthy weight and preventing infections.
CDC also suggested that moms-to-be get enough folic acid, a B vitamin, every day.
"If a woman has enough folic acid in her body at least one month before and during pregnancy, it can help prevent major birth defects of the baby’s brain and spine (anencephaly and spina bifida)," explained CDC. "Women can get folic acid from fortified foods or supplements, or a combination of the two, in addition to a varied diet rich in folate."
By taking healthy steps during pregnancy, expectant mothers can help their babies develop in a healthy way. And by being informed about their personal options and risks, pregnant women can make personal decisions about what prenatal screenings are right for them and their family.