What are all these tests for?
In New Zealand, as across the world, routine tests in pregnancy are recommended. These tests screen for potential problems and help to predict risks to your health and that of your baby. They help us to provide better care for you and your baby.
- A hemoglobin test checks to make sure your blood is able to carry enough oxygen and iron.
|Blood group and antibody screen
- This checks for your blood type (A,B,O or AB), Rhesus factor and any unusual red cell antibodies.
- If you are Rhesus Negative, you will require an injection called "Anti-D" if you bleed or if you have any invasive treatments during pregnancy.
- We also recommend that you have an Anti-D injection at 28 and 34 weeks as a routine.
- This injection may also be given to you after delivery if your baby’s blood group is positive.
- Checks for immunity to Rubella (German measles).
- Babies are at risk of abnormalities if a mother has rubella infection in the first three months of pregnancy.
- Most women are now immune to rubella, having already been vaccinated at school.
- This test will clarify your immunity status to Rubella.
- Checks for past exposure or immunity to Hepatitis B.
- This is a virus which infects the liver and can remain in the blood for many years without any sign of illness.
- The Department of Health recommends that all pregnant women are screened for this virus because if the mother is a carrier, the infection can be passed on to the newborn.
- Immunisation can be started at birth to prevent infection of these babies and allow them to grow up as healthy children.
- Screens for possible exposure to Syphilis, a sexually transmitted disease.
- This disease is now rare. However, testing is recommended because this infection can cause serious damage to babies when untreated.
- Treatment of the mother with penicillin will control the infection and prevent serious effects developing in babies.
- Screens for possible previous exposure to HIV, the virus that causes AIDS.
- Although this infection is relatively uncommon in New Zealand, the Department of Health recommends offering this test routinely, and encourages all pregnant women to have it.
- HIV can occur with no specific signs of illness, and can be passed from mother to baby during pregnancy, at delivery or through breast-feeding.
- Infection from mother to baby can be greatly reduced by newer forms of treatment of mothers during pregnancy and of newborn babies.
- Screens for Gestational diabetes and is recommended at 28 weeks or earlier if there are other risk factors present.
- Some women develop Gestational Diabetes, a problem with sugar or glucose control, during pregnancy. Gestational diabetes may lead to a big baby.
- Treatment with insulin may be necessary to reduce though not eliminate this risk.
- Furthermore, the chances of you developing diabetes after pregnancy is also increased so you will need at least yearly check ups with your own GP after pregnancy.
- Screens for cervical cancer. If your smear is due to be done, we can do this during your pregnancy or after your baby is born.
- Screens for sexually transmitted infection and bacterial vaginosis.
- Screening for Group B Streptococcus is offered at 36 weeks. This bacteria normally lives in the vagina but in 1 in 1000 cases can cause the baby to become very sick in the first week of life.
- Screening at 36 weeks will help us to identify babies at risk of this disease. If the bacteria is identified, you will be given antibiotics during labour to prevent transmission to your baby and reduce the risk for infection.
- Checks for sugar and protein in your urine.
- Screens for urinary tract infection and kidney problems.
- Ultrasound creates a picture of your baby on a computer screen using sound waves.
- It provides information on how many babies there are, your baby’s due date, your baby’s position, how well your baby is growing, the location of your baby’s placenta, and any abnormality.
- Ultrasound has been used routinely in pregnancy management for over 30 years, it does not cause miscarriage and is considered safe.
Up to 2% of all babies are born with some kind of abnormality. Most abnormalities will be minor, but some will be significant. Antenatal screening and diagnostic tests attempt to predict, diagnose or exclude these chromosomal and structural abnormalities. The aim is to provide information that help you plan and manage your pregnancy.
When you visit us at Birthright, we will discuss factors that help in deciding if you would benefit from genetic testing. These include: your age, your medical, obstetric and genetic background.
Various tests may be offered to check the health of your baby. Screening tests assess your risk of having a baby being born with certain conditions, such as spina bifida or Down’s syndrome, but cannot give a definite “yes” or “no” diagnosis. Diagnostic tests are more invasive but are able to confirm whether or not there is a problem.
For many women, the decision to have these tests is a difficult one: Talk to us, and let us help you with this decision.
|Nuchal translucency ultrasound scan
- This scan is performed at 11 to 13 weeks.
- It is a screening test for Down’s syndrome.
- It measures the thickness of the layer of fluid at the back of your baby’s neck.
- This nuchal translucency measurement is combined with your age and accurate gestational age to provide an individual risk assessment for you.
- This result tells you if you are low risk or high risk for a baby with Down’s syndrome.
- This is NOT diagnostic.
- Women who are high risk may consider further diagnostic testing such as amniocentesis, for clarification.
|Maternal serum screening
- This test is done at 15-17 weeks. MSS is a screening test for chromosomal abnormalities such as Down’s syndrome.
- MSS measures the amounts of three substances in a pregnant woman's blood: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and estriol (uE3).
- The levels of these substances help estimate the risk that a fetus may have certain defects.
- The test results are computed based on a woman's age, her weight, her race, and how far along her pregnancy is, among other factors.
- MSS doesn't diagnose a birth defect—it estimates the possibility that your baby has a birth defect.
- If your results indicated a higher-than-normal possibility, your next decision would be whether to have diagnostic testing, such as amniocentesis.
- Not every woman needs a maternal serum triple test (triple screen).
- Nuchal translucency results are combined with the results of maternal serum screening to give an individual risk assessment for chromosomal abnormality.
- MSS allows the screening process to be more accurate.
|Anatomy ultrasound scan
- This is a detailed ultrasound scan performed at 18 to 20 weeks, during which each part of your baby’s body is examined.
- It screens for structural abnormalities.
- This scan is able to detect 90% of babies with spina bifida and 50%-60% of babies with congenital heart abnormalities.
For genetic or inherited conditions such as Downs syndrome
or cystic fibrosis.
|Chorionic villus sampling (CVS)
- This test is performed at 10 to 12 weeks. Under ultrasound guidance, a fine needle is used to remove a small sample of placental tissue from the placenta.
- This tissue can provide genetic information from your baby. The advantage of CVS is it can be performed early in pregnancy.
- There is an associated miscarriage risk of 1-2%.
- This test is performed at 15 to 17 weeks.
It can also be performed at any time later in pregnancy if necessary.
- This is a test for genetic or inherited conditions such as Downs syndrome or cystic fibrosis.
- Under ultrasound guidance, a fine needle is used to remove a small sample of amniotic fluid from around your baby.
The fluid is cultured for your baby’s chromosomal makeup.
- Results are available in two weeks.
- There is an associated miscarriage risk of 0.5-1%