Tests in pregnancy: what to expect
This guide will help you understand what to expect with each medical test in pregnancy, when you’ll be tested and how to prepare.
During pregnancy, you’ll be offered tests to keep an eye on you and your baby’s health. It may seem like there are a lot of tests to keep track of but your midwife, GP or obstetrician will talk you through what’s needed and when. Here are the most common tests for each trimester, or stage, of pregnancy.
Your doctor will carry out a genetic assessment to determine what tests you should have. You may also like to consider testing for common genetic conditions such as cystic fibrosis, spinal muscular atrophy (SMA) and fragile X syndrome, which can cause significant health problems.
Once you’re pregnant, you’ll have blood tests to screen for infections including German measles (rubella) and chicken pox, vitamin deficiency and medical conditions. Testing for hepatitis B and C, HIV and syphilis is also recommended, because, although these conditions are relatively rare, the right management can reduce the chance of the baby acquiring an infection.
Your iron levels will be tested throughout your pregnancy, as well as other vitamins such as D and B12. A full blood examination looks at blood group, rhesus status, platelet levels, and for disorders such as anaemia and thalassemia. You’ll have these blood tests in your second and third trimesters too.
You’ll usually have an ultrasound at 6–10 weeks to confirm the baby’s due date and to check for twins or triplets. Another one at 12–13 weeks will check baby’s growth and development.
Testing for genetic conditions caused by chromosomal abnormalities is another consideration. Combined serum screening checks hormones in your blood at around 10 weeks, and an ultrasound measures the thickness of baby’s neck at about 12 weeks. These measurements are combined with your height, weight and age, to calculate the risk of your pregnancy being affected.
An optional screen for genetic abnormalities can be done anytime from 9 to 35 weeks. Non-invasive prenatal screening (NIPS) involves a blood test looking at DNA from the placenta that’s released into your blood. It checks the sex chromosomes, and for changes that could cause chromosomal conditions. The Harmony test is one example of this.
If combined serum screening and NIPS testing show there’s a high likelihood of a specific birth defect, you can choose to have further tests, like chorionic villus sampling (10–19 weeks) or amniocentesis (16–20 weeks). As these tests carry a risk of miscarriage they’ll only be done if your baby is at higher risk of having a birth defect.
Tracking your pregnancy
During your second trimester, your obstetrician or midwife will keep track of your blood pressure and weight, and your baby’s growth and progress.
Another ultrasound at around 20 weeks will check baby’s growth and the location of the placenta. It can also determine the gender of the baby (if you want to know).
At 26–28 weeks, screening for gestational diabetes involves a fasting blood test, with 2 more blood samples taken at intervals after a glucose drink, to test how your body responds to sugar.
At 36 weeks, a vaginal swab to check for group B streptococcus (GBS) – a bacterial infection that may have serious consequences – may be performed.
Preparing for tests
- If your test involves fasting, bring some food in your bag for afterwards.
- Ultrasounds often involve having an almost full bladder. Be sure to follow whatever instructions you’re given.
- If you’re concerned about any of your tests or nervous about needles, let your healthcare providers know.
- Bringing a support person to appointments can help with remembering information.
Mental health screening
Your doctor will screen you for depression using a questionnaire that asks set questions about how you’re feeling. This is important because 10-15% of women will be diagnosed with depression during pregnancy and in the postnatal period.
Signs can include reduced interest in things you’d normally enjoy; increased crying (sometimes for no apparent reason); feeling depressed or miserable consistently; and feeling irritable, angry or anxious a lot of the time.
Tests during pregnancy: what to consider
While tests aren’t mandatory, “the results of these investigations provide the woman, her family and care provider with valuable information that can be important to the woman’s choices around her pregnancy and labour care,” says Terri Barrett, president of the Australian College of Midwives.
Test results may indicate the need for further investigations or review by another health professional. “In some instances, identification of risk may mean a change in the initial plans for the pregnancy or birth including transferring the woman for higher-level care,” she says.
She says you need to be aware of the potential risks and benefits of any investigation or treatment before consenting.
Think about what you’ll learn from each test, and how you may use that information, says Dr Elder, president of the Victorian committee of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG), especially when it comes to genetic screening.
“Having an idea about where you stand and what your values are is a really important part of deciding around [these] tests. Women and their partners [should] discuss these issues before they decide whether to have [the tests].”
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