Whats and Whys of prenatal tests during pregnancy

Pregnancy is one of the most wonderful experience for a woman. However, at times it becomes too daunting because of the innumerable visits to hospitals, blood tests, scans and too much information from different sources. The most important point to remember at this stage is that all these hospitals visits, and tests are essential for your and your baby’s health and can even be a life saver in many pregnancies.
Amidst all the chaos and uncertainty, the best way forward is to understand the “What” and “Whys” so that you can take an informed decision. Here is list of most commonly done tests during pregnancy and what it means to you. If you fall under a high-risk pregnancy or suffer from any medical condition, your doctor will advise extra tests as per your clinical requirements.

1. Early Pregnancy/ 6-10 weeks

• Dating and viability Scan- To look if the position of your baby is correct, rule out any issues if you have bleeding or spotting, due date, look at the heartbeat of the baby etc.

• Blood test:

a) To identify the blood group and the Rh factor (+ ve or -ve). This is important as if there is a mismatch between the mother’s and baby’s blood, complications can arise. However, this can be managed by a simple vaccination around 28th week and 72 hours after birth.
b) Look at iron levels- rule out Anaemia
c) Immunity to Rubella- Also called as German Measles, it can lead to significant disabilities in baby if contracted in initial stages of pregnancy.
d) Thyroid Function-Abnormal functioning can have severe impact on baby’s development.
e) Infections – Hepatitis B and C, HIV, Syphillis, Herpes- infections can pass on to the baby leading to complications. There are vaccinations and medications to protect your baby if you have some infections.

• Urine Test:

 To identify traces of protein which can be a sign of Pre-eclampsia. Pre-eclampsia can have severe effects on you and your baby.
 Any infection that can impact your pregnancy.

2. Second Trimester:

• 11-13 weeks- Nuchal Translucency Scan (NT scan) to screen for Down’s Syndrome in the baby. Down Syndrome is a chromosomal abnormality resulting in learning and intellectual difficulties, with a range of health issues like cardiac abnormality, vision and hearing impairment etc. This test is sometimes combined with a blood test. If the test result shows high risk, you have the option of going for diagnostic tests like Amniocentesis or Chorionic Villus Sampling (CVS) for more certain results. The results of NT scan may also be used to look for multiple pregnancies and foetal heartbeat.

• 16 weeks- Urine test to screen for proteins indicative of Pre-eclampsia

• 20 weeks:

a) Anomaly Scan to rule out any physical abnormalities in the baby.
b)  It also helps to look at the positioning of the placenta (low or high) so that doctor can advise the next scan depending on the result.

• 24 weeks-:

a) Blood and Urine test to check the iron levels and protein levels respectively. This will rule out Anaemia and Pre-eclampsia.
b) Glucose Challenge Test (GCT) to rule out Gestational Diabetes. If you have any risk factor for Diabetes, you might have this test much earlier.

3. Third Trimester:

• 28 weeks:

a) Blood test to look at iron levels and antibodies. If your blood group is -ve, anti D injection may be offered to manage the antibodies.
b) Urine test to look for protein .

• 30 weeks:

a) Urine test
b) Growth scan- To see how well the baby is developing by measuring different growth parameters of the baby like head circumference etc.

• 34 weeks: Urine check

• 36 weeks: The doctor might suggest another scan and colour doppler studies to look at the baby’s position, umbilical cord, amniotic fluid etc. Swab test for Group B streptococcus might also be recommended between 35-37 weeks.

• 37 weeks: Urine check and possible internal check.

• 38-39 weeks: if you have not delivered yet, urine check might be recommended.

• 40 weeks: Your doctor will discuss options for future management.

Apart from these tests, blood pressure , weight etc. will be tested regularly/ at each appointment

Remember, this list is applicable to normal or uncomplicated pregnancies. You doctor will consider your family history, previous medical history and any current complications before recommending specific tests.


This article is only for information and educational purposes. It does not intend to replace any medical advice or diagnosis.




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