Get ready to be tested: Antenatal screenings you can expect during your pregnancy

by | May 10, 2018

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As you hold that little piece of plastic in your hand, you stare in amazement at the two biggest life changing marks you’ll probably ever see. Two stripes. A positive pregnancy test.

And that’s just the first test. The pregnancy journey is peppered with tests from the beginning. But don’t feel overwhelmed. Here’s what you can expect and when to expect them.

The tests are divided into three categories: routine tests, screening tests and diagnostic tests.

Routine tests are performed frequently throughout the pregnancy. Some may be carried out at every appointment. These tests are to check that both your and your baby’s wellbeing are on track and that no problems are developing.

Generally, a screening test is done when you have no specific symptoms for a potential problem, but you do have a risk factor: e.g. for X age group there is a one in 250 chance of Y happening.

A diagnostic test can be used to confirm a suspected condition once a screening test has indicated that there is a possibility that you have the condition.

What will be done, and when?

The tests during your first visit to your caregiver are as follows:

  • Antenatal screening
  • Blood pressure
  • Height measured
  • Weight measured
  • These will be done at each appointment:
  • Urine test
  • Blood pressure
  • Weight

If you are seeing a midwife, baby’s heart rate will be measured as well as fundal height. The fundal height is the distance, in centimetres, from your pubic bone to the top of the uterus, and is used to assess foetal growth and development.

If you are consulting a gynaecologist, you may have an ultrasound done at certain appointments.

Antenatal screening test

When: First appointment.

How: A blood test.

Why: This blood test will determine your blood group if it is unknown, which is important especially at the time of birth should you haemorrhage and need blood. It checks red blood cell count which, if it is low, is an indicator of anaemia. Rubella immunity will be confirmed, and HIV and syphilis will also be tested.

Risks: No risks.

Urine test

When: Each antenatal appointment.

How: Urinating onto a testing strip.

Why: This test looks for various substances in the urine that shouldn’t really be there in noteworthy quantities, such as sugars, proteins, ketones and bacteria. High sugar levels could indicate pre-existing type two diabetes or gestational diabetes later on in pregnancy. Protein levels are monitored, as an elevation of protein could be a sign of pre-eclampsia. The presence of ketones could be an indication of starvation because your body is using stored or ingested fat for energy as a result of not getting enough energy from a normal source of  energy like carbohydrates. This is not a good thing, especially as you are trying to grow and nourish a baby. Signs of a urinary tract infection are picked up through the presence of white or red blood cells, or bacteria in the urine.

Risks: No risks.

Routine Ultrasound

When: Throughout pregnancy.

How: A non-invasive diagnostic tool using sound waves to create an image of your baby.

Why: An early ultrasound will be done to confirm and assess the viability of the pregnancy. Pregnancy dating will be done at this ultrasound, as well as subsequent ultrasounds. The number of foetuses will also be assessed at this time, and if there are twins, the type of twins can be determined here.

Ultrasounds done between 16 and 20 weeks might be able to indicate the sex of baby (only if the baby plays along and doesn’t hide the important bits).

At each ultrasound, the heartbeat will be checked, as well as growth measurements. These specific growth measurements will indicate normal growth patterns, and should any irregular growth patterns occur, these can be investigated further.

The gynaecologist  will also look out for foetal structural abnormalities between weeks 12 and 14, locate the placenta and be on the lookout for too much, or too little amniotic fluid between weeks 20 and 22.

Risks: No known negative effects.

Nuchal scan

When: 11 – 14 weeks

How: An ultrasound scan where the collection and translucency of fluid at the back of the baby’s neck is measured.

Why: A high reading can point to abnormalities such as a heart defect or Down syndrome and other chromosomal abnormalities.

Risks: No known negative effects.

Alpha-fetoprotein (AFP)Test

When: 16 – 18 weeks

How: Blood test

Why: Screening for any possible abnormalities such as spina bifida (malformation of the spinal cord), anencephaly (absence of brain and part of skull) or open abdominal wall defects.

Risks: Dating of pregnancy must be accurate as inaccurate dating could result in a false positive.

Triple test (aka Down Syndrome test)

When: 15 – 22 weeks

How: Blood test

Why: Indicator of baby’s risk of spina bifida or Down syndrome.

Risks: Dating of pregnancy must be accurate as inaccurate dating may cause hormone levels to be interpreted incorrectly.

Chorionic Villus Sampling (CVS)

When: 9 – 14 weeks (doctor requested)

How: An invasive diagnostic procedure where chorionic villi cells are removed from the placenta  at the point where it attaches to the uterine wall. An ultrasound guides a thin catheter through the cervix or through the abdomen to the placenta. The needle draws a sample of tissue at the correct point and is then removed.

Why: CVS detects genetic disorders such as cystic fibrosis and chromosomal abnormalities such as Down syndrome. This test can be performed earlier than an amniocentesis.

Risks: Though the test is deemed safe, it is still an invasive procedure that does carry a 1% chance of miscarriage. Infection, spotting and cramping are also possible post-procedure.


When: 16 – 18 weeks, especially for moms over 35 (doctor requested)

How: An invasive diagnostic test, similar to a CVS, where a fine needle is inserted into the uterus through the abdomen under ultrasound guidance to remove a small amount ofamniotic fluid.

Why: Amniotic fluid contains live foetal cells, which contain DNA as well as other substances such as AFP.  These substances are tested to reveal the possibility of chromosomal abnormalities and other birth defects, such as Down syndrome, cystic fibrosis, muscular dystrophy, sickle cell disease and other similar diseases.

Risks: As with CVS, there is a very small chance that the procedure could possibly result in a miscarriage.

Apart from the risks that the above tests may involve, one also needs to consider the emotional choices that may need to be made once the results have been established. Always discuss options and risks with your caregiver before having any of the ‘riskier’, non-routine tests done.