Week 8 instalment from NaturalChildbirth in their Pregnancy Week by Week series, this week Dr Lindsay Reid covers the types of tests you may be offered during pregnancy, why it may be needed and what is entailed.
Tests during pregnancy can form an important part of your overall antenatal care. They are offered so that the midwife and the maternity care team can check that all is well with you and your baby and, to reassure you too. If they find a problem they can advise you about what to do next.
What are the most common antenatal tests?
- Diagnosis of pregnancy
- Maternal physical examinations / checks
- Blood tests
- Urine tests
- Ultrasound scans
Diagnosis of pregnancy.
You can do this test yourself as we discussed in Week by week: week 2, with a home testing kit which can be bought at the pharmacist – most women do. However, your midwife may want to do another pregnancy test – to confirm for herself. This will be a similar urine test to the one that you have done.
Your booking visit.
For more details of the Booking or early assessment visit see Week by week: week 6. The tests done at this visit as well as all that you tell her give the midwife an overview of your health and an assessment of how you are now.
Remember that you are a ‘partner’ in your care. It’s important that you should understand what tests are offered and why. You don’t have to accept every test offered if you feel strongly about any particular one.
Your physical examination.
Your first physical examination of pregnancy may well be the longest. It takes an overall look at your physical fitness as well as your pregnancy. Height and weight are usually recorded and in some clinics you will be weighed at each subsequent visit – you need to put on some weight during pregnancy but not too much.
Your breasts will be examined and your heart and lungs will be listened to. Your abdomen may be palpated if you are over twelve weeks at this visit. A vaginal examination is not usually done unless there is a specific reason.
At each subsequent antenatal visit, whether at home or at the clinic, the midwife will give you a ‘top-to-toe’ examination including abdominal palpation. This is to make sure that your pregnancy is progressing normally and your baby is growing well. She will also test your urine and record your blood pressure.
At each antenatal visit you will be asked to provide a specimen of urine to test for protein and glucose. If either of these showed up further testing would be needed. Protein in the urine could indicate a urinary infection (see Pregnancy we k by week : week 4 for the link with progesterone) or, a sign of Pregnancy Induced Hypertension (PIH). If PIH is diagnosed it would need to be carefully monitored. Glucose in the urine could be a sign of the onset of diabetes which sometimes occurs in pregnancy.
The midwife will discuss with you why blood tests are taken in pregnancy. She will help you make an informed choice about the tests that are available. Blood is taken with your permission, at the first visit to check:
- Full blood count, to observe the condition of your blood and includes:
- Your blood group. This will enable blood to be obtained quickly for you in the unlikely event of your needing it;
- Level of haemoglobin. This tells whether you are anaemic or not;
- Whether your blood is Rhesus positive or negative (Rh+ or Rh-). Fifteen percent of the population is Rh-. If you are Rh- and your baby is Rh+ then you would require further blood tests at intervals during your pregnancy to make sure no problems were arising.
- Syphilis. This test is done as a matter of course along with the others.
- Human Immunodeficiency Virus (HIV) antibodies. The policy for taking blood for HIV varies. It is likely that the test will be offered to you in pregnancy. If you do not want your blood to be tested for HIV then say so.
- Hepatitis B. This test is not done everywhere but screening can be offered in pregnancy.
- Rubella or German Measles. Pregnant women are routinely tested for rubella as this virus can damage the growing embryo/fetus if the mother develops it under twelve weeks of pregnancy. So, if you are found to be not immune to rubella you must be very careful in early pregnancy to keep away from anyone with rubella. After your baby is born, you can be immunised against it if necessary.
What other blood tests are done?
- Further Haemoglobin tests. It is important that you don’t become anaemic especially while pregnant and your midwife will want to test again for this later in your pregnancy.
- Alpha fetoprotein (AFP) screening. This test was/is sometimes used at around 15-16 weeks of pregnancy as a marker for neural tube defects such as spina bifida. It has mostly been superseded by the use of ultrasound.
AFP is present in small amounts in the mother’s blood during pregnancy. It is also present in the amniotic fluid – the fluid round the baby in the uterus. The levels of AFP in the mother’s blood are highest in early pregnancy and get less as the pregnancy progresses. In this way it is known how much AFP there should be in the blood at any stage of pregnancy and levels that are too high or too low can be picked out. Again, make sure that you talk about this test and if you don’t want it for any reason, then say so.
Reasons for raised levels of AFP include:
- Over assessment of how many weeks pregnant you are
- Multiple pregnancy
- An open neural defect of the fetus like spina bifida.
- false result.
Reasons for low levels of AFP are:
- under-assessment of how many weeks pregnant you are.
- a possible association with Down’s syndrome.
Sometimes the blood may be tested along with the AFP test for abnormal hormone levels. This gives a more accurate result for Down’s syndrome. If necessary, a repeat test and an ultrasound scan will be offered.
Early testing for abnormalities
Nuchal Screening This test for Down’s syndrome measures the thickness of the fold in the baby’s neck via a scan. Nuchal screening can be done from ten – fourteen weeks of pregnancy and is usually done in combination with maternal age and biochemical markers for Down’s syndrome.
Chorionic Villus Sampling (CVS) is another test for Down’s syndrome and other chromosomal abnormalities. This test can be done at 10-12 weeks of pregnancy. It involves taking a tiny piece of placental tissue for testing under continuous ultrasound guidance.
An ultrasound assessment is now offered to most women in the UK. Most women are happy for this to be done. It is painless and you will be able to see a ‘picture’ of your baby on the screen. However, if you don’t want a scan then say so.
An ultrasound scan is done:
- to confirm the expected date of your baby’s birth
- to confirm how many weeks pregnant you are
- to watch the baby’s heart beating
- to check for anything about the baby which might cause concern e.g. spina bifida, Down’s syndrome. (Nuchal screening)
- to measure the baby’s rate of growth. Here, scans can be done at intervals and the baby is measured.
- to check where the placenta (afterbirth) is
- as a guide if an amniocentesis is being done.
- to measure the baby’s blood flow if there is concern about the baby’s growth.
- to observe the baby’s movements in utero
The number of scans performed varies from person to person according to the need arising.
An amniocentesis involves drawing off some of the fluid round the baby in the uterus. This is done by inserting a very fine needle through the mother’s abdomen. An ultrasound scan is done at the same time so that the obstetrician can see exactly where the needle is going. A very small amount of fluid is drawn off and sent for testing.
Reasons for doing an amniocentesis include:
- Chromosomal analysis as in eg Down’s syndrome. (Most common reason.)
- Neural tube defects as in eg spina bifida.
- Deoxyribonucleic acid (DNA) analysis. This involves isolation of genes causing conditions such as Duchenne muscular dystrophy. Work is still being done on this sort of analysis.
There is a slight chance of miscarriage with amniocentesis.
How long will the results take to come back?
Due to advances in technology, the result from the laboratory where the amniotic fluid is cultured, can now come in two stages. An initial set of results (usually for Down’s syndrome) is followed by a full culture result after 2-3 weeks.
If you are advised to have an amniocentesis, or any tests which carry a risk of miscarriage, or, even if you are just not sure, make sure you talk it through thoroughly with your partner and any members of the maternity care team. You can also ask for counselling if it is available.
You can also be told whether your baby is a boy or a girl, although if you don’t want to know, say so.
Make very sure that you know why you want the tests. If an abnormality is found, will you terminate the pregnancy? Or do you simply think that you will cope better if you are prepared for what is ahead? If so, ask yourself if the risk of miscarriage is worth taking when you wouldn’t consider a termination anyway. Follow your instincts and make sure that any decisions you make are right for you and your baby and have the full support of your partner.
This is a test you do yourself. It involves your keeping watch on your baby’s movements and recording when you have felt ten separate movements on a daily chart. We’ll discuss this further in week 16.
Tests done in pregnancy are developing all the time. Their accuracy depends on the level of knowledge /research regarding the test, the ability of the person performing the test and the skill of the person interpreting the test. Not every maternity unit offers the same level of testing.
Antenatal tests are offered for the benefit of you and your baby. If you are worried about any of them please feel able to ask your doctor or midwife – they’re there to help. It’s important for you to know what is happening and feel happy about every aspect of your pregnancy.
Baby’s development at 8 weeks after conception
Now your baby’s neck is beginning to develop. Her head is becoming rounder and more recognisable. Her neck is beginning to develop, facial features are becoming more apparent and her eyelids begin to close to protect her immature eyes. Internal organs continue to grow; movements continue to progress; length is about 3 cms.
Now you are at a major stepping stone: from eight weeks the official term for the developing baby moves from embryo to fetus. Progress indeed!
In week 9, as well as having a look at how you might be feeling, and the latest development of ‘the wee one’, it is probably an appropriate time to have a look at that amazing organ – the placenta.