SingaporeMotherhood | Pregnancy

September 2024

Prenatal Tests and Scans to take when you are Pregnant

You’ve taken that first test to find out if you are pregnant, and got a Big Fat Positive. Congratulations! Now it’s time to think about the prenatal tests and scans that you may choose to take throughout your pregnancy. If you are in good health, there may not be a need to go through all of them. However, many women opt to do all the prenatal tests and scans, just to ensure that their pregnancies are progressing well, especially if they are over 35 years of age.

At KK Women’s and Children’s Hospital (KKH), prenatal risk assessment in the first trimester now also includes screening for preeclampsia (a pregnancy condition involving high blood pressure and its complications), Dr Samantha Yeo, Consultant at the Department of Obstetrics and Gynaecology, KK Women’s and Children’s Hospital, tells us.

“In addition, we also test for Rubella antibodies, an indication of the patient’s immunity to Rubella infection and response to past MMR (Measles, Mumps and Rubella) vaccination, together with routine antenatal blood tests,” Dr Yeo says.

Some of the more recent significant developments in prenatal tests include non-invasive antenatal testing (NIPT) as a first-line option for down syndrome screening, together with advanced ultrasound techniques such as 3D and 4D ultrasound imaging in specialised situations, she adds.

(See also: True story: “I had pre-eclampsia with two pregnancies”)

Prenatal Tests and Scans by Trimester

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Dr Yeo shares that these antenatal scans, tests and vaccinations are recommended for patients at KK Women’s and Children’s Hospital (KKH):

First Trimester

  • Dating scan to determine the estimated delivery date (EDD).
  • Blood tests to screen for anaemia, thalassaemia, blood group, Rhesus D (RhD) status and red-cell antibodies, hepatitis B, syphilis and HIV infection, German measles (rubella) immune status
  • Down syndrome screening tests.
  • The flu (influenza) vaccine, which is the most effective way to get protected against flu. It can be safely given at any point in pregnancy. Flu is a serious illness that can lead to complications for mothers and babies and is more dangerous if contracted during pregnancy.

(See also: Pregnant? Use this Pregnancy Checklist to Plan for the next 9 months)

Second Trimester

  • 20-week (screening) scan to screen for foetal anomalies and low-lying placenta.
  • Blood tests to screen for anaemia and gestational diabetes (KKH was the first hospital in Singapore to offer gestational diabetes screening to all pregnant patients between 24 and 28 weeks, starting from January 2016).
  • Taking the whooping cough (pertussis) vaccine from 16 weeks to 32 weeks into pregnancy to help protect the baby. Whooping cough is a serious respiratory illness that can cause deaths in newborn babies.

Third Trimester

  • Growth scan to screen for foetal growth restriction, and to monitor baby’s size and well-being.
  • If the patient has a Rhesus negative blood group, a Rhogam injection will be given at week 28.
  • Vaginal swab to screen for Group B Streptococcus infection.

Going beyond Prenatal Tests and Scans

Apart from prenatal tests and scans, Dr Yeo also recommends vaccinations for mums-to-be to contribute to the health and well-being of mother and baby.

Antenatal tests and scans help identify potential health issues in the foetus, allowing for early intervention and management. The results of these investigations can enable better informed decision-making and allow healthcare professionals to provide the necessary support and counselling if needed.

“Vaccinations in pregnancy protect both mother and baby against potentially serious illnesses during pregnancy which are highly preventable,” she says.

Together, these lead to better outcomes for both mother and baby.

Here’s a more in-depth look at the tests and scans that you can do during pregnancy.

At your First Prenatal Checkup

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At your first prenatal check-up, the nurse will draw your blood to test it for various conditions.

Full blood count

To measure haemoglobin levels and helps detect anaemia (low levels of red blood cells that carry oxygen in your body). Your blood will also be screened for Thalassemia, a blood disorder that can be transmitted to your baby.

Blood typing

To show which blood group you belong to (A, B, O or AB) and determine your Rhesis (Rh) status. If you are Rh negative, regular injections throughout pregnancy can help prevent the production of antibodies that may harm your baby.

Hepatitis B

Hepatitis B may affect your liver function and can be transmitted to the baby during birth. If you have it, your doctor will start you on an immunisation regime to reduce transmission. It will also minimise the chance of your baby developing liver dysfunction and liver cancer later in life.

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Syphilis

This sexually-transmitted disease is now rare. However, doctors will offer the test as a precaution. Early treatment with antibiotics can help prevent stillbirth and foetal deformities.

HIV

The HIV (human immunodeficiency virus) causes AIDS (acquired immunodeficiency syndrome). An HIV-positive mother can transmit the virus to her baby during birth and through breastfeeding. With medication, a Caesarean section, and avoidance of breastfeeding, the risk of transmission goes down.

Other blood tests

These screen for infections like Toxoplasmosis and Cytomegalovirus (TORCHES), and for genetic disorders like cystic fibrosis, sickle cell disease and Tay-Sachs Disease. These tests may also be done depending on the mother’s ethnic background and medical history, says Dr Quek Swee Chong, consultant obstetrician & gynaecologist at ASC Clinic for Women at Gleneagles Medical Centre.

(See also: 10 Prenatal Pilates Classes in Singapore for Pregnancy Fitness and Conditioning)

Viability and Dating Ultrasound Scans

When First trimester

This early ultrasound scan (from 6 to 8 weeks gestation) confirms that the pregnancy is developing normally. It also checks that it is in the right location (not ectopic). The scan will also identify the foetal heartbeat. From 8 to 10 weeks of gestation, the scan can give you the most accurate expected date of delivery (EDD), says Dr Quek.

NIPT (Non-Invasive Prenatal Testing)

When From week 9

These detect foetal DNA from the mother’s blood and screen for common chromosomal disorders. They can also determine gender. While the tests cannot detect every genetic disorder, they are highly accurate for Down syndrome. However, because this DNA comes from the placenta and not from the foetus, there is a small chance that the results are not 100 per cent accurate, says Dr Quek.

Even though both the OSCAR (see below) and NIPT (above) tests are not compulsory, Dr Quek advises that all pregnant women — regardless of age — have the option to do them. In Singapore, there are several companies (Harmony, MaterniT21 Plus, Panorama, EasyDNA, and iGene) that offer the test. Each has slightly different screening panels for the various genetic disorders such as Down syndrome, Edwards Syndrome, Patau Syndrome, Turner Syndrome and Jacobs Syndrome.

(See also: Parenting her Son with Down syndrome is hard but “love can change our hearts and our minds” says this Mum)

OSCAR (One-Stop Clinic for Assessment of Risk for foetal anomalies)

When Weeks 11–14

This tests for Down syndrome (Trisomy 21) and other chromosomal problems. The risk is calculated using an ultrasound scan to assess the thickness of the skin in the neck of the foetus (Nuchal Translucency), and a blood test from you. This test is about 90 per cent accurate and results are usually available within the same day.

Chorionic Villus Sampling (CVS)

When Weeks 11–12

This also helps to determine chromosomal or genetic disorders in the foetus. A biopsy needle is inserted through the abdomen (under ultrasound guidance) and into the placenta to withdraw a small amount of placental tissue. The procedure takes a few minutes and is relatively painless. Results take two to three weeks to be ready.

Amniocentesis

When Weeks 16–20

Under ultrasound, a hollow bore needle is guided through the abdomen and into the amniotic fluid surrounding the foetus. A small amount of amniotic fluid is removed for testing. Results are available after two to three weeks.

Both CVS (above) and Amniocentesis are invasive tests. Hence doctors usually recommend them only for women whose previous children have a chromosomal/genetic disorder. Women who have a high-risk result from the OSCAR or NIPT tests may also choose to take the tests. Both tests carry a small risk of miscarriage (CVS 0.5–1%; Amniocentesis 0.25–0.5%).

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Detailed Ultrasound Scan

When Weeks 19–22

This test helps to detect structural anomalies in the foetus. In particular, it looks for abnormal heart structures, facial clefts, head, abdomen and limb size, placental position, doppler blood flow, cervical length, and the amount of amniotic fluid present.

Oral Glucose Tolerance Test (Screening for Gestational Diabetes)

When Second trimester

Women with gestational diabetes are at higher risk of developing Type 2 diabetes later in life, says Dr Quek. For this test, the mum-to-be has to fast overnight. The next morning, a blood sample is taken. She then drinks a 75g glucose drink. Two hours later another blood test is taken. The results are usually available within one to three days.

(See also: Gestational Diabetes 101 – Are You at Risk?)

Ultrasound Growth and Doppler Scans

When Late in second trimester/going into third trimester

Some women may need to undergo repeat ultrasound scans to monitor the growth of the foetus. These usually include doppler flow studies of the vessels supplying blood to the foetus.

Group B Streptococcus (GBS)

When Week 35

This group of bacteria is found in the genital area of around 30 per cent of women and is detected via a vaginal swab. If you are positive for GBS, your doctor will prescribe antibiotics. Generally, the condition does not cause any problems. However it can affect the baby as the baby passes through the birth canal during delivery, says Dr Quek.

Prenatal Tests in Pregnancy: Nothing to be afraid of!

It may be stressful to think about having to do prenatal tests and scans. Didn’t we already have enough of these in school? Still, we’d suggest taking these tests and scans as helpful guides and assurance that your pregnancy is going well, or to find solutions and options otherwise. That way, you can ensure that you are doing what you can for yourself, and your little one. All the best for a healthy pregnancy and a smooth delivery!

Featured image: senivpetro on Freepik

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Prenatal Tests and Scans to take when you are Pregnant