Third Trimester Tests

Third trimester tests include the routine tests conducted at each prenatal visit urine test, uterine examination, blood pressure checking, weight checking and foetal heart beat checking.

In addition to these, you will have to undergo tests like GroupB streptococcus screening, kick count test, non-stress test, contraction stress test and biophysical profile.

Third Trimester Tests

GroupB streptococcus screening

GroupB streptococcus is a bacterium, which if present in your genital tract, has a chance to be passed on to your baby during delivery. So you will be tested for GBS late in pregnancy, between 35 and 37 weeks. Nearly 30 percent of women carry this bacterium. If you are one among them, to prevent your baby from being infected, you will be given antibiotics during labour.

Kick Count test

This test is done to feel the baby’s movement late in pregnancy. If you are past your due date, or have any chronic health problem or if you are carrying multiples, you may be asked to undergo this test. It should take 10 minutes to two hours for a baby to move 10 times. If you can feel ten kicks under two hours, it would mean the baby is normal. If the kicks are less than ten within two hours or decreases each time the test is taken, your doctor may perform a non-stress test to see how the baby is doing inside. The baby is likely to be most active during the time you eat, so test taken at this time can provide the desired result.

Non-stress test

This test measures the baby’s heart beat as it moves. This is done every week, mostly from 38- 42 weeks in women who are posed with a greater risk in pregnancy because of preexisting health problems or pregnancy induced conditions like hypertension or because they are carrying multiples, or they have past their due date. This is a sort of confirmation test to the kick count test. If the previous test shows the baby to be less active than normal, the non-stress test can confirm the non-reactivity through monitoring of baby’s heart beat in its movement. The baby’s movement can be said to be normal, if the heart beats faster for atleast 15 seconds, on two separate occasions within 20 minutes test span. However, non-reactive result does not straightaway mean that something is wrong with the baby. Result of non-reactivity may be because the test was taken much earlier, when the child had not matured enough to show reactivity, or the baby might have been in sleep when the test was taken. 

The test may be repeated after an hour or other tests like contraction stress or biophysical profile may be taken to confirm if the child is doing well inside If your doctor is sure the baby is not doing well, she may probably decide on inducing labour.

Contraction stress test

This test has a greater risk than other similar tests and so not generally recommended unless you have a high-risk pregnancy. This test is taken when you have mild and intermittently occurring uterine contractions before labour starts, to measure how fast or how slow the baby’s heart beats during a contraction. It determines how healthy the placenta is, to provide the baby with the necessary oxygen when contractions occur. If the oxygen supply to the baby from the placenta, does not decrease from the required level, then the baby’s heart beat will be normal during a contraction, and thus the contraction test makes sure that during labour, the baby can get enough oxygen from the placenta and can cope up well with the stress of labour. Sometimes, contractions are stimulated with oxytocin, and the heart beat is measured.

Bio-physical profile

This is a combination of non-stress test and ultrasound used to determine foetal health in the third trimester. This test may be recommended as an alternative to contraction stress test, if that is believed to pose a greater risk to you and your baby. This test is performed in women who have chronic health problems like diabetes, or gestational hypertension and whose pregnany is categorised as high-risk pregnancy or if they have past their due date. Women with pregnancy complications like presence of too less or too much of amniotic fluid, decreased foetal movement or problems with the placenta are also offered the Bio-physical profile test. The test is performed once or twice in a week by 32-34 weeks or even earlier in third trimester, based on your condition. Bio-physical profile measures five foetal characteristics—foetal heart beat with the help of non-stress, body movements, muscle tone, breathing movements and the amount of amniotic fluid with ultrasound. If any of these characteristics show up abnormality, in particular the foetal movement and the level of amniotic fluid it indicates the baby is facing problems within the uterus, and the doctor will probably respond by inducing an early delivery.