RCSI Women's Health

Frequently Asked Questions

What is the advantage of finding out if my baby is healthy or is developing normally?

Some people do not want to undergo any prenatal tests because they feel that they would not "do anything" if the results return as abnormal, meaning that they would never choose to undergo a pregnancy termination. While this is an entirely personal decision, it is important to realise that there are many advantages to prenatal diagnostic tests that have nothing to do with pregnancy termination. For example, many parents who have been told in the delivery room that their newborn baby has a serious abnormality describe feelings of tremendous shock and anger. Many state that they would have preferred to have known the news in advance of delivery so that they would have time to prepare.

Another advantage of knowing about the health of the baby in advance is that it provides your obstetrician and paediatrician an opportunity to make sure that all the right steps are in place to improve the health of your baby. For example, it may be necessary for you to deliver the baby by caesarean section, or at a particular hospital, or at a particular time to ensure that relevant paediatric specialists are immediately available. Occasionally, if it is confirmed that your baby has such a serious abnormality that the baby cannot survive, you may be able to avoid a caesarean section, or avoid transfer of the baby to another hospital.

What is the difference between a screening and a diagnostic test?

Screening tests do not tell you for certain if the baby is healthy or has a problem. They simply provide you with more information on the "odds" or chances of a problem. For example, based on your age your doctor may tell you that your chance of having a baby with Down syndrome is one in 200. Before deciding what to do with this information, you could have a screening test done to give a more accurate assessment of risk. If the screening tests suggests that your actual chance is closer to one in 1,000, for example, you may prefer to avoid a diagnostic test such as an amniocentesis. On the other hand, if the screening tests suggests that your actual chance is closer to one in 10, for example, you may prefer to have a diagnostic test to find out for certain. The main advantage of screening tests is that there is no risk of miscarriage. The main disadvantage is that screening tests do not tell you for certain if your baby is healthy or has a problem. Only a diagnostic test can tell you this.

Diagnostic tests tell you for certain whether or not your baby has a particular problem. For example, an amniocentesis involves placing a needle into your uterus to obtain some amniotic fluid from around the baby. This fluid can be tested in the genetics laboratory to tell you for certain if your baby has a condition like Down syndrome or Trisomy 18. The main disadvantage of these diagnostic tests is that there is a small risk that placing a needle in your uterus might trigger a miscarriage. The chances of miscarriage depend on the particular type of test, how far along in pregnancy you are, and is often quoted as about one in 200 (0.5%).

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