Tests you may be offered - second trimester
- Blood tests
- Vaginal swab
- Kick chart
- Genetic testing
After your initial blood tests, you should not require further routine blood tests until about 28 weeks of the pregnancy (ranging from 26 to 30 weeks). Women with medical conditions, such as diabetes, high blood pressure, epilepsy, thyroid conditions or metabolic disorders or women experiencing pregnancy complications, may need additional tests before this time, as required.
Your caregiver will either take the blood themselves during the pregnancy visit, or order your blood tests to be taken by someone else (either at the hospital or a private pathologist). The blood tests offered at around 28 weeks are:
- Glucose tolerance test or GTT
- Full blood count or FBC
The glucose tolerance test (GTT) usually needs to be taken over a 1 or 2 hour period (depending on whether it is a short GTT or a long GTT). Therefore, you will need to set aside more time to have this test at this particular pregnancy visit. If your blood group is Rhesus negative, you will also need to have a group and antibodies blood test to screen for antibodies.
In recent years it has become fairly standard to offer women a low vaginal swab test to screen for a bacterium called Group B streptococcus (also known as Strep B or GBS) at around 28 weeks of the pregnancy. However, some caregivers delay this test until about 34 to 36 weeks of the pregnancy.
The vaginal swab is taken from the lower vagina, just inside the entrance. Therefore the woman can usually perform this test herself at home (if given the swab to take with her) or in the toilet during the pregnancy visit. (Your caregiver should not need to perform a vaginal examination, or use a speculum to take this test).
The swab used is like a long cotton bud and is placed about 2 to 3 centimetres inside the vagina before putting the swab into a sterile container. Some caregivers prefer to do an anal swab (or a swab of the rectum), instead of (or as well as) a vaginal swab. But this is not generally accepted as being routine.
It is now fairly common for caregivers to offer women a routine ultrasound at around 18 to 20 weeks of the pregnancy. This ultrasound is aimed at:
Measuring the growth of the baby and relating this to how far pregnant you are estimated to be. (Although estimating a due date at this stage of the pregnancy can be up to 10 days out, with earlier ultrasounds being more accurate at dating.)
Trying to detect any obvious physical defects in the baby.
Identifying the location of the placenta and seeing if there is an adequate amount of amniotic fluid surrounding the baby.
Some caregivers have ultrasound machines in their private rooms to perform 'informal' ultrasounds at every pregnancy visit. However, this is not essential and you can decline having this done if you prefer. Generally, ultrasounds done in this way can only provide a limited amount of information. You would need to have an ultrasound performed by a qualified technician and reported on by a qualified ultrasonographer, to definitely confirm your caregiver's ultrasound findings.
A 'kick chart' is a graph or grid printed on a piece of paper with spaces to record the daily movements of your baby, usually after about 26 to 28 weeks of the pregnancy. In New Zealand, kick charts are mainly used for women who:
- Express concerns about their baby's movements.
- Have a health condition that may affect their baby.
- Experience pregnancy complications that may put their baby at increased risk of being unwell after birth or distressed during the labour.
A kick chart is particularly aimed at detecting if a baby becomes unwell
While kick charts are not used routinely in New Zealand, they tend to be in other countries (such as the USA).
Some genetic tests are performed during the 2nd trimester of pregnancy. These include a blood test at around 16 to 18 weeks of pregnancy called an alphafetoprotein test (or 'AFP'), as well as the amniocentesis test (or 'amnio').