Although getting pregnant is a wonderful experience for most women, it can become daunting with all that time spent at the doctor’s clinic. It suddenly feels like there’s too much information to absorb and too many decisions to take on which tests are necessary without it becoming a financial burden and adding to the stress levels. While the process of having blood withdrawn frequently and having people give unsolicited advice can be stressful, it’s important to remember that some of these tests are absolutely essential and can save the life of the baby and the mother too. We have compiled a list of tests that need to be done before and during every stage of pregnancy.
1. Pre-conception tests:
The first test, in fact, starts before conception with a carrier genetic screening that is done to detect if the parent might be a carrier for potentially serious genetic disorders. Some of the more common disorders screened for include cystic fibrosis, sickle cell disease, thalassemia, and Tay-Sachs disease, but there are more than 100 others that can be tested for. Thalassemia is particularly common amongst people of Indian origin.
Sometimes parents can be carriers without showing symptoms but can pass on the gene for that disorder to their children. Typically, if the mother is not a carrier, the father may not need to be tested but if both parents are carriers, there is a chance that the baby would be affected. As ethnicity often determines the prevalence, genetic testing may focus on different diseases. Usually, the family background and ethnicity are factors taken into consideration and the doctor may call for a genetic test if any abnormality is suspected. The genetic counselor also helps the couple to understand which type of genetic test is relevant to their case and what type of outcome they can expect from the test.
The ‘CBC’ is an important test before conception or in early pregnancy. This measures a variety of factors in your blood, such as the number of white and red blood cells that you have. Crucial indicators in your CBC test results are the hemoglobin, hematocrit and platelet count.
Hemoglobin is a protein in the blood that delivers oxygen to your cells, and hematocrit is a measure of red blood cells in the body. Anemia results when either of these counts is low and needs to be addressed by the doctor. The platelets help in blood clotting and are critical as they ensure that blood loss during pregnancy does not exceed the normal levels. If your count is unusually low the doctor needs to conduct further tests and resolve the issue.
2. Early pregnancy tests in the first trimester:
The Rh (or Rhesus) factor test looks for a protein on the surface of the red blood cells. About 85% of the population is Rh positive as it expresses the protein. If however, you lack the protein (Rh negative) and the father has it, complications can occur as the baby can inherit Rh-positive blood from the father. The result for it would be the baby’s blood mixing with the mother’s and the maternal immune system attacking the baby’s blood, causing a condition in the child known as hemolytic anemia. This condition is more of a concern for second pregnancies as an intermingling of blood can occur during the first delivery and the next time a Rh-negative mother gets pregnant with a Rh-positive child, her antibodies will attack the fetus. This can be prevented by a simple vaccination around the 28th week of the pregnancy and again 72 hours after delivery of the first child.
Screening for sexually transmitted diseases (STDs), such as HIV/AIDS, syphilis, herpes and hepatitis B and C, gonorrhea and Chlamydia should be done early on as well. This time, the point is crucial to prevent these diseases from being transmitted to the fetus. STDs can cause a range of complications for a baby besides transmission of the disease such as early delivery, eye infections (from gonorrhea and chlamydia), or much more severe consequences such as miscarriage or stillbirth (caused by syphilis). Administration of medication can dramatically reduce the transmission rate of HIV from 25% to 7%. In the case of hepatitis B, if the virus is contracted early in the pregnancy, there is a less than 10 percent chance the disease will be transmitted to the baby. If it is contracted later in the pregnancy, the transmission rate increases to approximately 90 percent. Chlamydia, syphilis, and gonorrhea can be cured with baby-safe antibiotics.
3. Testing at 8 weeks:
Immunity towards Rubella virus is important to be ascertained during pregnancy as a baby affected by German measles may end up with multiple birth defects, such as sight and hearing abnormalities, as well as congenital heart defects. The test is administered before conception or after 8 weeks of onset of pregnancy. It is advisable to get vaccinated before pregnancy, failing which vaccination for Rubella can be done after the birth of the child.
4. Testing at 10-12 weeks:
For women over the age of 35, CVS testing is recommended to test for chromosomal abnormalities. The test involves withdrawal of chorionic fluid employing ultrasound using a needle and allows for chromosomal testing 8 weeks before amniocentesis. CVS test is unable to identify neural tube defects, such as spina bifida, which can be detected by amniocentesis. It also carries a higher risk (1%) of miscarriage than amniocentesis.
5. Testing at 12th week:
Besides checking the developing baby’s heartbeat, a fetal ultrasound test is useful for discovering the gestational age of the baby which helps in planning pre-natal care and predicting a delivery date. It also helps in locating the fetus to ensure that it is properly situated in the uterus and not in the fallopian tubes, which would indicate a dangerous condition known as an ectopic pregnancy. Fetal ultrasounds also help in confirming that the baby is growing correctly and does not have any fetal abnormalities. It also helps expecting parents know if they can expect just one or multiple births.
Image source: whattoexpect.com
6. Testing at 16 weeks:
Amniocentesis is done at 16-20 weeks of pregnancy to allow for detection of chromosomal abnormalities. This is recommended for women over the age of 35 as the chances of chromosomal abnormality increase greatly at that age. The technique uses a needle employing ultrasound to extract amniotic fluid that is then analyzed for genetic defects, particularly neural tube defects that cause birth defects due to abnormal development of the brain, spinal cord, or their coverings. Amniocentesis carries a lower risk of miscarriage than CVS, about 1 in 400.
7. Testing at 20 weeks of pregnancy:
Alpha-fetoprotein (AFP) is found in the amniotic fluid, fetal blood, and in the mother’s blood. Neural tube defects are indicated by abnormal levels of AFP that necessitates the need for a more detailed ultrasound analysis of the baby’s spine. Abnormal levels are also indicative of complications later such as stillbirth. This is usually done as part of multiple marker screening. Multiple marker screening comes in two varieties: the triple screen test and the quad screen test. The triple marker screen looks for three substances in the fetal blood or placenta: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and estriol. The quad screen looks for inhibin A (Inh-A) in addition to the three substances in the triple screen.
By combining the test results from these screens along with factors such as the mother’s age, weight, and ethnicity, doctors can evaluate the possibility of developing neural tube defects like anencephaly or Spina Bifida, or even Down’s Syndrome, all prevalent in the Indian population.
The tests are about 80 percent accurate in predicting neural tube defects. Since the tests tend to deliver high false-positives, a doctor may recommend further testing such as an amniocentesis. A Sonogram is also helpful to determine if the pregnancy is actually further along than previously thought and might explain the abnormal results.
8. Testing at 28 weeks:
Glucose test for diabetes is done at around 28 weeks of pregnancy. Gestational diabetes is a temporary condition affecting 2-5% of all pregnant women in which insulin fails to break down enough glucose in the blood. There is an approximately a 30% chance that you have developed the condition if the Glucose Challenge Test (GCT)comes out positive and the doctor would the conduct a glucose tolerance test (GTT). In the event that you develop gestational diabetes, your doctor can help you develop a diet, exercise, and possible insulin-supplementation plan. The condition is usually resolved after the birth of the baby. In addition to this, several other conditions may also be determined by testing the urine sample such as protein in the urine, indicating a kidney infection; bacteria, pointing to a urinary tract infection; and ketones indicating dehydration.
Image source: www.mamazone.pl
9. Testing at 36 weeks:
The Group B Streptococcus test is done at 36 weeks to determine whether the mother is a Strep B carrier so that antibiotics may be administered to minimize the risk of an infection to the baby at birth. About 25% of healthy women test positive for Strep B and if the test comes back positive, there is a one in 200 chance that a baby will contract the disease during birth, which could potentially result in serious conditions like sepsis, pneumonia, and meningitis. Intravenous administration of antibiotics during delivery allows the risk to drop to one in 4000. It is particularly recommended for a woman whose water breaks more than 18 hours before delivery, who has a fever during labor, who goes into labor early, or who has a history of giving birth to a child who contracted the disease.
10. Testing blood pressure:
The doctor monitors blood pressure for a condition called Preeclampsia, indicated by increased blood pressure. Testing of blood and urine is done and the condition is indicated by a low platelet count in blood and by the presence of protein in the urine.
Preeclampsia affects 7 percent of all pregnant women, especially first-time mothers and those carrying multiple children. It is a rising of the blood pressure due to the pregnancy and typically happens late term and can have serious health risks for both mother and child, such as a lack of blood flow to the placenta. However, high-blood pressure alone does not confirm preeclampsia and must be verified with protein in the urine, as well.
During labor, the heart rate of your baby needs to be monitored as due to contractions, the flow of oxygen to the fetus may be limited resulting in change in baby’s heart rate during birth. Any changes outside of normal range (approximately 110 to 160 beats per minute) would mean that the baby is not getting enough oxygen necessitating the need for corrective steps.
In conclusion, while the array of tests on offer during pregnancy might be bewildering, it’s important to be informed of the health of the baby and also monitoring one’s one health. It’s certainly necessary to feel reassured and be one step ahead of a potential health problem. The tests outlined above serve to provide a complete checklist for an expectant Indian woman but it’s always a good idea to speak to your gynecologist who would take your family history and ethnicity into account before recommending specific tests that you may otherwise overlook.
About the author: Dr Jaishree Srinivasan has a doctorate in Molecular Genetics, a post-doc in Molecular Virology and over 15 years of work experience (both research and business) in the life science industry that span the spectrum of drug discovery and development, science publishing and healthcare across various geographies (US, Singapore, China and India).