First trimester tests can offer valuable information about your health during pregnancy. One of the goals of your first visit to the obstetrician’s office is to confirm your pregnancy and determine whether you or your baby is at risk for any health problems. To confirm your pregnancy, you may have a urine pregnancy test, which checks for hCG, a hormone in pregnancy.
Tests during first trimester find problems in pregnancy like ectopic pregnancy, molar pregnancy, low haemoglobin levels in mother, gestational diabetes and high blood pressure which can later lead to preeclampsia. These medical problems, if not treated can put your baby at risk for problems like preterm birth and low birth weight. These tests can also tell you about your baby’s health, and possibility of a birth defect or a chromosomal abnormality in your child. Results can be inaccurate, but the chances of this happening are low.
Confirmation-To confirm your pregnancy, you may have a urine pregnancy test, which checks for hCG, a hormone elevated in pregnancy.
Blood tests: During one of your initial examinations, your doctor will identify your blood type and Rh (rhesus) factor, screen for anaemia, check for immunity to rubella (German measles), and test for hepatitis B, syphilis, and HIV.
This panel of tests includes, but is not limited to:
(a) Complete Blood Count(CBC)-Complete blood count denotes the levels of Hemoglobin in the mother. For Indian standards 11mg/dl is the minimum requirement in pregnancy. A CBC counts the number of different types of cells that make up your blood.
(b) Blood grouping and typing (including Rh screen)
(c) Rubella testing- Rubella (sometimes called German measles) can cause birth defects if a woman is infected during pregnancy. Your blood is tested to check whether you have had a past infection with rubella or if you have been vaccinated against this disease. if you have not had rubella previously or if you have not been vaccinated, you should avoid close contact with anyone who has the disease while you are pregnant because it is highly contagious. If you have not had the vaccine, you should get it after the baby is born, even if you are breastfeeding. you should not be vaccinated against rubella during pregnancy.
(d) Hepatitis testing- Hepatitis B and hepatitis C viruses infect liver. Pregnant women who are infected with hepatitis B or C virus can pass the virus to their fetuses. All pregnant women are tested for hepatitis B virus infection. if you have risk factors, you also may be tested for hepatitis C virus.
(e) Tests for sexually transmitted diseases- All pregnant women are tested for syphilis and chlamydia early in pregnancy.
(f) HIV testing- If a pregnant woman is infected with HIV, there is a chance she can pass the virus to her fetus. HIV attacks cells of the body’s immune system and causes acquired immunodeficiency syndrome (AIDS). If you are pregnant and infected with HIV, you can be given medication and take other steps that can greatly reduce the risk of passing HIV during pregnancy, labor and delivery.
(g) Urine tests- You will also be asked early on for a urine sample so that your doctor can look for signs of urinary tract infection and, if necessary, to confirm your pregnancy by measuring the hCG level. These tests are-.
(i) Urine analysis- Your urine may be tested to assess for urinary tract infection, high levels of glucose for gestational diabetes and protein levels to diagnose early signs of preeclampsia.
(ii) Urine Culture- A urine culture is done when there is a suspicion for infection. It tests your urine for specific bacteria causing urine infection.
Thyroid Stimulating Hormone: Your doctor will order thyroid stimulating hormone (TSH) test even if you do not have a history of thyroid disease. This is because a major percentage of pregnant women may have an underlying thyroid disorder that is unsuspected and that will cause problems during pregnancy.
An ultrasound is a simple, painless procedure. A wand that uses sound waves will be placed on your belly. The sound waves will let your doctor see the baby.
Your doctor may do an ultrasound done in the first trimester to get an idea of your due date.
Screen for Foetal Problems
In the later part of the first trimester you will be offered genetic testing. Talk with your doctor about the pros and the cons before proceeding to see if genetic testing is right for you and your pregnancy.
Doctors use this to screening test to determine a woman’s risk of carrying a baby with Down syndrome (trisomy 21) or other chromosomal abnormalities. It can also help determine the risk for certain birth defects like heart abnormalities.
This is done in two parts:
Blood sample (maternal blood screening). This test measures the levels of proteins in the blood. Having abnormal levels of the proteins PAPP-A (maternal serum pregnancy-associated plasma protein-A) and higher levels of beta-hCG (maternal serum beta human chorionic gonadotropin) can indicate a higher-than-average risk of carrying a baby who has chromosomal abnormalities.
Ultrasound screening (nuchal translucency screening). This is done between 11 and 14 weeks of pregnancy. This exam measures the space in the back of the baby’s neck. Extra fluid in the back of the neck (behind the neural tube) may point to a higher risk of chromosomal abnormalities.
When a woman undergoes both the blood and ultrasound screening, her doctor usually will calculate the results together. Age is also a consideration with determining these results, since women of advanced maternal age (35 and older) are at a higher risk of having children with chromosomal abnormalities.
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’s important to remember that some of these tests are absolutely essential and can save the life of the baby and the mother.
Those who are not shown to be high risk in the first trimester are still offered a second trimester screening. It consists of more blood tests, checks for chromosomal abnormalities and neural tube defects, and helps to confirm the findings from the first trimester screen.
Talk to your doctor if you have questions about these screenings or your results.
- Dr Prerna Gaur