You may also be offered an ultrasound scan. It is very common for a scan to be done in early pregnancy (around 12-14 weeks) and perhaps another later on.
The main reasons for a scan are:
- to help date the pregnancy;
- to check for more than one baby;
- to check the baby’s growth and development;
- to monitor the placenta
Ultrasound is increasingingly efficient at -diagnosing abnormalities, notably spina bifida and Down’s syndrome. Practices vary, but if you want your partner there he should he able to accompany you, and you may be offered an instant photograph of the scan, although you will probably have to pay for it.
Depending on your age and your family’s medical history, you may also be offered other tests. If you are nor, and would like them, ask.
1. The nuchal scan
Done at 11-13 weeks, an ultrasound scan measures the thickness of the nuchal pad (fluid) in the baby’s neck. A thicker than average pad may indicate abnormal chromosomes, so you may be offered an amniocentesis.
2. The AFP (alphafetoprotein) test
This is done at 16-18 weeks. A blood sample is checked for high or low levels of AFP, which may be associated with spina bifida or Down’s syndrome. An ultrasound scan can rule out or confirm the diagnosis.
3. The triple test
Sometimes called the Bart’s test or serum screening, this is done at about 15 weeks. A blood sample is tested for chemicals that help to calculate the risks of Down’s syndrome or spina bifida. You may then be offered a diagnostic scan or amniocentesis.
4. Chorionic villus sampling (CVS)
This is done at around 10-1 / weeks and involves removing a tiny frond of the tissue that forms the placenta and examining it for chromosomal abnormalities, especially Down’s syndrome.
5. Amniocentesis
Carried out at around 18 weeks, amniocentesis involves having a needle inserted in your abdomen to draw off a sample of amniotic fluid. The sample is then checked for abnormalities, especially Down’s syndrome, but also spina bifida, muscular dystrophy, cystic fibrosis and haemophilia. It will also determine the sex of the baby: if you do not want to know, say so.
6. Getting the results
None of these tests is perfect. Both CVS and amniocentesis carry a small risk of miscarriage and any test could increase your anxiety (although, since the results usually show that there is nothing to worry about, some women are more reassured by them). None of the tests offers a totally certain diagnosis and even routine ultrasound has its critics.
If a test shows that your baby is likely to have an abnormality, you may want to consider a termination. You should be given a chance to talk this through before you have the test. Even if you know you could not consider a termination, you may want the time to prepare for having a baby with special needs.
Depending on where you live, your ethnic origin and family history, you may also be offered other, less common tests. You should be given the chance to discuss the associated risks and benefits before you decide whether to go ahead.
