Antenatal scans, checks and screening tests

Throughout your pregnancy you will be offered a variety of checks, including blood tests and antenatal scans. These tests are to help make your pregnancy safer and to assess the development and well-being of you and your baby. Some tests are carried out to screen for particular conditions in you or your baby. You are under no obligation to have any test.

It is important you understand the purpose of all tests. You should discuss these tests with your partner, midwife or GP, so that you can make an informed choice about whether or not to have them. You may be offered some leaflets on the screening tests being offered.

Weight and height

You will probably be asked your weight or weighed at your first check-up. Routine weighing is not generally carried out now as research has shown that weighing during pregnancy is often inaccurate, can be a source of considerable anxiety, and unhelpful in clinical terms. On average, a healthy, average-sized woman who eats normally in pregnancy will gain around 2 stone, but women can gain anything from almost nothing to up to 3½ stone, whilst still having a normal pregnancy and a healthy baby. During your pregnancy it is important to eat the right foods and take regular exercise. Much of the extra weight is due to the baby growing, but your body will also be storing fat ready to make breast milk after the birth. Your height will be measured along with your weight to calculate your BMI (body mass
index).

Urine

You will be asked to give a sample of urine at your check-ups. This is to check for infection (usually a sample is sent away at your first appointment) and for protein, which can be a sign of pre-eclampsia. Pre-eclampsia affects 10% of pregnancies and can be life-threatening if left untreated. It can cause fits in the mother and affect the baby’s growth. Women with the condition can feel perfectly well.

Blood pressure

Your blood pressure will be taken at every antenatal visit. A rise in blood pressure could be a sign of pre-eclampsia.

Blood tests

Blood tests will be offered during your pregnancy. Remember to ask what they are for before choosing to have them and ask to have the results explained to you, but they usually test for:

• Your blood group – they test your blood to see if it is rhesus negative or positive. Some mothers are rhesus negative (usually this is not a worry for the first pregnancy). Some rhesus negative mothers will need an injection of ‘anti-D’ after the birth of their first baby to protect their next baby from anaemia. It is now recommended that rhesus negative mothers are also given an injection of “anti D” in pregnancy (usually at 28 and weeks and 34 weeks) – this is done to make sure that the blood of future babies is not affected by rhesus disease.
• To see if you are anaemic - Usually offered at your first checkup and later on in pregnancy. If you are found to be anaemic you can be offered treatment straight away.
• Infections- You will be offered tests for:
  • Susceptibility to rubella (German measles) – If you get rubella in early pregnancy, it can seriously damage your unborn baby. If your test shows you are susceptible to infection, your midwife or GP will discuss what this means for your pregnancy. Future pregnancies can be protected by the MMR vaccine, which should be offered to
    you following delivery. This blood test does not exclude rubella infection in this pregnancy, so if you are concerned about contact with rubella or concerned about a rash discuss this with your GP or midwife.
  • Syphilis – It is vital to detect and treat any woman who has this sexually transmitted disease as early as possible to reduce the risk of the infection affecting the baby. Left untreated, syphilis during pregnancy can lead to miscarriage, stillbirth or the birth of a disabled child.
  • Hepatitis B – This virus can cause liver disease and may infect your baby if you are a carrier or are infected during pregnancy. If you are affected by hepatitis B, an appropriate plan of care for you and your baby can start straight away in pregnancy. A full course of vaccination for the baby, beginning shortly after birth,
    reduces their risk of being affected by hepatitis B.
  • HIV (Human Immunodeficiency Virus) – This is the virus that can cause Aids. HIV infection can be passed to a baby during pregnancy, at delivery or after birth by breastfeeding. If you are found to be HIV+, you can start treatment and receive expert care straight away which will dramatically reduce the risk of your baby becoming infected and improve your own health.

It is very important to be aware that the infections listed above can still be acquired during pregnancy after you have had a negative test result. This is particularly the case for sexually transmitted infections such as HIV, hepatitis B and syphilis, if you or your lover take risks such as needle sharing or having unprotected sex. Your midwife or GP can discuss this with you.

Screening for abnormalities in the baby

• Blood tests are carried out from 11-20 weeks. They are used to measure the levels of proteins and hormones in the mother’s blood in order to work out the chance of the baby having a condition such as Down’s syndrome or spina bifida. Combined, integrated and triple tests are types of blood test taken in early pregnancy. A combined test uses one blood test and a test known as nuchal translucency to find out the baby’s chance of having Down’s syndrome.
• Fetal anomaly screening uses ultrasound scanning to find certain abnormalities in the baby. This is usually carried out at 18-20 weeks, and can identify certain heart problems and conditions that may need treatment as soon as the baby is born. Fetal anomaly screening can also identify abnormalities such as cleft lip, and confirm spina bifida.
• Sickle cell and thalassaemia are both inherited blood conditions. Routine screening has recently been introduced across England, and pregnant women should now be offered screening for these conditions.

Antenatal scans – What is a Nuchal Scan?

A nuchal scan is a sonographic prenatal screening scan (ultrasound) to help identify higher risks of Down’s syndrome in developing babies, particularly for older mothers who have higher risks of such pregnancies. The scan is carried out when you are 11-13 weeks pregnant and assesses the amount of fluid behind the neck of the fetus – also known as ‘the nuchal translucency’. Babies at risk of Down’s syndrome tend to have a higher amount of fluid around the neck. The scan may also help confirm both the accuracy of the pregnancy dates and the fetal viability. Its high definition imaging may also detect other less common chromosomal abnormalities.