Types of health tests during your pregnancy

Scheduled visits are important health tests during your pregnancy

It is recommended that you have the following tests during your pregnancy. These test results will help in assessing the well-being, of you and your baby.

Blood tests in early pregnancy

Blood tests are ordered by your GP and are to be checked for the following:

Ultrasound scan

• This is a procedure which uses sound waves to form images of your baby.
• There are two scans routinely taken during your pregnancy.
• The first scan is called the dating scan and it is usually organised by your GP for between 7 and 13 weeks plus 6 days. This scan is most often used to ascertain your baby’s due date.
• The second routine scan is called ‘level 2 morphology scan’ and this is done between 18 and 20 weeks of pregnancy. This is a very detailed scan that looks closely at your baby, the position of the placenta and how your baby is growing. The scan takes about an hour.

Early screening for Trisomy 21 (Down Syndrome), Trisomy 18 and 13

This test is available to you between 11 and 13.6 weeks. It is a combined test that consists of:

• a blood test done by 13.4 weeks gestation
• a scan of your baby revealing possible chance of having a baby with Down Syndrome, trisomy 13 or 18.

Genetic material (DNA)

• DNA is arranged in the human body in packets called chromosomes. 
• Every cell in the human body should contain 46 chromosomes.
• There are two copies of chromosomes 1 to 22 (one from each parent) plus two sex chromosomes.
• Trisomy means that there are three copies of a certain chromosome in every cell.
• For example Trisomy 21 (Down Syndrome) means three copies of chromosome number 21 in each cell.
• This affects the way a baby develops and causes conditions that may affect the baby’s life.
• Chromosomal abnormalities can occur in any pregnancy but are more common in babies of older mothers.
• The first trimester screening result measures the nuchal translucency (thickness at the back of the foetal neck) by ultrasound.
• The blood test measures the level of two hormones produced by the placenta (PAPP-A and BHCG).
• It is very important that you have both tests with the blood test first to obtain an accurate result.
• This test is specifically designed to screen for Trisomy 21, Trisomy 13, and Trisomy 18.
• Other genetic abnormalities may be revealed after further investigating the test results. 
• Remember some abnormalities are mild but some can be severe in nature.
• If you are unsure whether you wish to have this screening test, please talk to your GP or at your first midwife appointment (if before 13 weeks plus 6 days).

Understanding test results and options

• If you do not understand your test results, please discuss this at your next antenatal appointment.
• The higher the number the lower the likelihood that your baby will have Trisomy 21, 18 or 13.
• You can ask for further tests.
• No tests will be done without your informed consent and counselling from one of our obstetric doctors.
• Please remember the majority of pregnancies with abnormal results will have a normal outcome. 
• Not all abnormalities that might affect a baby can be identified before birth.

Second trimester screening for Down Syndrome and Spina Bifida

• You can take a blood test between 14 and 20 weeks plus 6 days if you didn’t do the first trimester screening.
• It also identifies if there is an increased chance of neural tube defect that is present in Spina Bifida.

Women who have a negative blood group

• All women who are Rh-Negative receive injections called “anti-D” at 28 weeks and 34 weeks.
• This prevents your body from making antibodies to your baby’s red cells.
• If you have a negative blood group (Rh Negative) it is important that you understand what this means for you and your baby. Please discuss it with your midwife or doctor.
• It is very important you have your recommended 26-week blood tests including your blood group and red cell antibodies checked before your 28-week antenatal check.
• Anti D cannot be given until results from this test are available.

Diabetes in pregnancy

It is recommended to have a POGTT test for diabetes in pregnancy or ‘gestational diabetes' at 26 weeks. You should have this even if you had this test early in pregnancy. Undiagnosed or uncontrolled diabetes may lead to:

Blood tests at 26-28 weeks

• Bloods are taken for diabetes (POGTT), haemoglobin and red cell antibodies.
• The results of these tests will be discussed with you at your 28-week visit.
• It is important to take these tests prior to your 28-week antenatal appointment.

Group B Streptococcus

• At 36 weeks you may be weighed and asked to provide a specimen of urine.
• The midwife will also ask you to collect a vaginal swab. It is used to detect a bacteria called Group B Streptococcus (GBS).
• 15-25% of the normal population carries these bacteria. It is not harmful to you.
• In 1-2% of cases, it can be passed onto the baby during birth. This can cause the baby to become ill with symptoms of sepsis.
• If GBS is detected, we recommend that you be treated with antibiotics (given into your vein) during labour.
• This will help protect your baby from infection and reduce their risk to around 0.1%.
• If you are GBS positive, your baby will be closely observed for the first 24 hours after birth.
• If antibiotics were not given in labour, your baby will need to be observed for 48 hours and may need care.