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First Trimester Screening

Verified By Apollo General Physician July 12, 2021 3203 0
First Trimester Screening
First Trimester Screening

Pregnancy is a beautiful phase in a woman’s life. If your pregnancy has been confirmed, you will be told to get the first trimester screening done.

The first trimester test or screening involves a combination of two tests, mainly a  blood test for the mother and ultrasound of the fetus. It is scheduled between one and 12th or 13th week of pregnancy. These tests are done to detect if the baby has any kind of defects or deformities. The tests will be able to detect any chromosome defects including trisomy 13 or 18 or trisomy 21, which is Down Syndrome. In addition to this, the first trimester screening may also detect if the baby has any heart problems or chromosomal abnormalities.

What are the basic things you need to know? 

First trimester screening consists of the following:

  • A blood test to measure levels of two pregnancy-specific substances in the mother’s blood — pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotropin (HCG)
  • An ultrasound exam to measure the size of the clear space in the tissue at the back of the baby’s neck (nuchal translucency)
  • First trimester screening is done to evaluate your risk of carrying a baby with Down syndrome. The test also provides information about the risk of trisomy 18.
  • Down syndrome causes lifelong impairments in mental and social development, as well as various physical concerns. Trisomy 18 causes more severe delays and is often fatal by age 1.
  • First trimester screening doesn’t evaluate the risk of neural tube defects, such as spina bifida.
  • Because first trimester screening can be done earlier than most other prenatal screening tests, you’ll have the results early in your pregnancy. This will give you more time to make decisions about further diagnostic tests, the course of the pregnancy, medical treatment and management during and after delivery. If your baby has a higher risk of Down syndrome, you’ll also have more time to prepare for the possibility of caring for a child who has special needs.

Are there any risk factors?

No, there are no major risks associated with the first trimester screening during pregnancy as it helps detect defects. Neither the blood tests nor the ultrasound would have any adverse effect on the baby or the mother. 

However, sometimes the results may not be 100% accurate. For instance, the false-negative results could show the baby is normal, while he or she may have an issue. On the other hand, a false-positive test may show a health issue, while the baby could actually be healthy. Nonetheless, it is pretty rare.

How do you prepare for the First Trimester screening??

It is not a complicated test, hence the mother may not have to do anything specific before going for the first trimester screening. You can eat what you eat normally and drink sufficient water, as advised by the doctor.  Even if you are on medications, there is no need to worry about the first trimester screening. Make sure you wear loose clothes on the day of the test.

What should you expect from the first trimester test?

As already discussed, the first trimester screening is done in two parts:

  1. Blood test of the mother: Sample blood of the mother is taken by injecting a needle in the arm. The sample is then sent to a laboratory for further examination. 
  2. Ultrasound: You would have to lie on the doctor’s table or examination table. The professional will use a device and apply gel on your tummy to receive the sound waves. The sound waves will be reflected on the monitor in the form of images. Based on the image, size and clear space, the doctor will analyze the baby’s health and let you know if it is normal. Once the ultrasound is done, you may get back to your routine.

What are the possible results?

After getting the blood results and ultrasound results, your doctor will also use your age and other medical conditions to detect if your baby has any kind of birth defect. Usually, trisomy 18 is detected at this stage.

First trimester screening results are given as positive or negative and also as a probability, such as a 1 in 250 risk of carrying a baby with Down syndrome.

First trimester screening correctly identifies about 85 percent of women who are carrying a baby with Down syndrome. About 5 percent of women have a false-positive result, meaning that the test result is positive but the baby doesn’t actually have Down syndrome.

When you consider your test results, remember that first trimester screening indicates only your overall risk of carrying a baby with Down syndrome or trisomy 18. A low-risk result doesn’t guarantee that your baby won’t have one of these conditions. Likewise, a high-risk result doesn’t guarantee that your baby will be born with one of these conditions.

When do you need to see a doctor?

Once pregnancy is confirmed, you can consult a doctor for first trimester screening. First trimester screening is optional. Test results indicate only whether you have an increased risk of carrying a baby with Down syndrome or trisomy 18, not whether your baby actually has one of these conditions.

Call 1860-500-1066 to book an appointment


First trimester screening is just the beginning of a series of pregnancy tests. It is a good way to know about the health of the baby by detecting serious conditions, if any. 

Frequently Asked Questions (FAQs)

Is it possible to know the gender of the baby through first trimester screening?

The first trimester screening is not done to check the gender of the baby. Also, the baby is too tiny in the initial months (in the first trimester) of the pregnancy, and so it is not possible to know the gender. In addition to this, gender should not be disclosed as per the laws of the land .

Are there any risks of Down Syndrome for the baby?

There are no risks associated with the first trimester screening for the mother or the baby. In case the baby has any defects related to Down Syndrome, the first screening of the pregnancy will help you know about it.

What happens if the test results show positive for Down Syndrome?

If the doctor has detected positive results for any birth defects, then they will suggest what to do next.

Is it possible to detect the possibility of twins in the first trimester screening?

It depends on various factors. Sometimes, it is possible to detect if there are twins in the mother’s womb. However, it might not be possible in case the foetuses have changed their positions in the womb. You can wait for a few more months to confirm if there are twins or not with other pregnancy tests in the second trimester.

What are the symptoms of first trimester pregnancy?

There are various symptoms that a woman can experience in her first trimester. For instance, some may experience nausea and vomiting, tiredness and mood swings. Some may experience heightened symptoms such as irritation, swollen breasts, bloating, constipation, nasal congestion and cramping or light spotting.

Verified By Apollo General Physician

Our expert general medicine specialists verify the clinical accuracy of the content to deliver the most trusted source of information, making the management of health an empowering experience.

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