The appropriate timing for NIPT【supervised by doctor】

What is NIPT?

NIPT is a test that uses blood samples from the mother to test for chromosomal abnormalities such as 21 trisomy (Down syndrome), 18 trisomy (Edwards syndrome) and 13 trisomy (Patau syndrome) in the foetus. Also known as ‘non-invasive prenatal genetic testing’ or ‘non-invasive prenatal genetic testing’.

The sensitivity and specificity of NIPT are 99.9% and 99.90% for 21 trisomy (Down syndrome), respectively, and the test itself is considered to be extremely accurate compared to conventional blood-based prenatal diagnosis. It can therefore more accurately detect whether a baby has a possible chromosomal abnormality.

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Why undergo NIPT?

One of the benefits of undergoing prenatal diagnosis, including NIPT, is that it helps to ensure that you are fully prepared for the birth of your child.

Many people are concerned that if one of their relatives has a congenital disease or genetic abnormality, their baby will have a similar condition. It is also known that the probability of chromosomal abnormalities occurring in the foetus is higher when the mother is older.

However, advances in medical technology, such as NIPT, now make it possible to test for the possibility of chromosomal abnormalities in the foetus at an early stage of pregnancy.

Although NIPT has been criticised as ‘sorting out life’, if prenatal diagnosis reveals a high probability of genetic disorders, including chromosomal abnormalities, before birth, it can be used to carefully prepare for a better environment for babies born with disorders caused by these disorders. In terms of respect for the individual, the test is of great significance.

Unfortunately, there are also cases where pregnancy interruption may be considered, such as when a disease that cannot be treated with current medical science is detected. Under Japanese law, abortion is permitted up to 21 weeks and 6 days of pregnancy. Abortion after an advanced number of weeks of pregnancy is performed by forcing the birth to occur with drugs or other means, which is extremely stressful on the mother, so if an abortion is chosen, it should be done as soon as possible.

In any case, it is a very important choice for the family and it is strongly recommended to have a NIPT as soon as possible to give the couple time to think it over and reach a decision.

When should the NIPT test be taken?

NIPT is an easy test that is less physically demanding on both mother and child, but to use the results correctly, it is necessary to have a correct understanding of when the test should be taken. This section explains when NIPT can be taken and for how long, along with the reasons why.

When can I start having NIPT?

Appropriate timing of NIPT testing based on clinical research
Hiro Clinic NIPT can be performed after the pregnancy has been diagnosed by ultrasound.The NIPT test uses a substance called ‘cell-free DNA’ of the foetus in the mother’s blood, which is said to increase around six weeks of pregnancy.

This is said to increase at around six weeks’ gestation.

The second test is offered free of charge and guarantees accurate results based on clinical research. We use the latest medical technology and clinical research to provide safe and reliable NIPT. Please feel free to contact us for further information.

There is no deadline by which you have to undergo NIPT. However, Hiro Clinic NIPT recommends that you take the test before 14 weeks of pregnancy if possible.

This is because NIPT is only a screening test to indicate whether there is a possibility of chromosomal abnormalities in the foetus, and if it is positive, a chromosome test such as an amniotic fluid test will be necessary.

As the amniotic fluid test is only available after 15 weeks’ gestation, it is recommended that NIPT is performed by 15 weeks’ gestation at the latest.

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If the NIPT result is positive

Hiro Clinic NIPT recommends that if the result of NIPT is positive, an amniotic fluid test should be performed as a definitive test.

The reason for this is that, as mentioned above, NIPT is a screening test and not a definitive test that examines the foetus’ chromosomes themselves. Therefore, even if the NIPT is positive, the possibility cannot be ruled out that the baby has no chromosomal abnormality but is diagnosed positive for a variety of reasons, i.e. false positive.

What is amniotic fluid testing?

An amniotic fluid test is a ‘test of the chromosomes themselves in the amniotic fluid’. A thin needle is inserted into the mother’s abdomen and amniotic fluid is taken directly. The amniotic fluid is rich in the baby’s chromosomes, and a chromosome analysis is carried out to check for abnormalities in the baby’s chromosomes and genes, and whether any genetic disorders are present, in order to make a definitive diagnosis.

The appropriate period for amniotic fluid testing is said to be between the 15th and 18th week of pregnancy, when the amniotic fluid is increasing.

Risks in testing include a reported risk of miscarriage, with the risk of miscarriage from amniotic fluid testing being around 0.3-0.5%. In addition to the risk of miscarriage, other risks such as infection and sepsis have also been reported, although extremely rare.

Can NIPT be performed in obstetrics?

NIPT is not a test that can be performed by any obstetrician. The test is only available at medical institutions that offer it.

There are certified and non-certified medical centres that offer NIPT.

Certified facilities (formerly NIPT)

Certified facilities are those accredited by the Japanese Medical Association and the Japanese Society of Obstetrics and Gynaecology. As of 2 November 2022, 373 facilities nationwide had been accredited (169 core facilities, 178 linked facilities and 26 provisional linked facilities).

Certified facilities also collect data on NIPT and conduct clinical research to verify the accuracy of the test. In order to undergo NIPT at a certified facility, the patient has to fulfil strict requirements to be eligible for the test. In larger hospitals, such as university hospitals, this is handled by a department known as the Department of Genetic Medicine.

Non-certified facilities ( latest NIPT)

Unlike certified facilities, non-certified facilities are those that are not certified by the Japanese Medical Association and the Japanese Society of Obstetrics and Gynaecology. Some people may feel uneasy when they hear the word ‘non-certified’. However, just because a facility is not accredited by the Japanese Medical Association and the Japanese Society of Obstetrics and Gynaecology does not mean that it is illegal to carry out tests. These are medical institutions where doctors are on staff and medical procedures such as blood sampling are carried out correctly. Those who do not meet the prescribed conditions and cannot undergo NIPT at a certified facility can still undergo the test at a non-certified facility. Non-certified facilities are not bound by obstetric and gynaecological regulations and are able to offer advanced testing. They offer tests for partial deletions, partial duplications, microdeletions, sex chromosome aneuploidy and autosomal recessive inheritance, which are becoming more common in the world. It is also possible to undergo testing for less than 10, so those who want a faster diagnosis should opt for a non-certified centre.

The appropriate timing for NIPT【supervised by doctor】

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What pregnant women are not eligible for NIPT testing?

NIPT is available to almost all pregnant women.

Pregnant women who should definitely consider NIPT are those who meet the following criteria. The occurrence of chromosomal abnormalities in the foetus is relatively common in those with the following conditions.

• Pregnant women of advanced age
• Pregnant women whose maternal serum marker tests suggest that the foetus may have a chromosomal numerical abnormality
• Pregnant women with a history of carrying a child with a chromosomal numerical abnormality
• Pregnant women in whom either parent has a balanced Robertson translocation, suggesting that the foetus may have 13 or 21 trisomy
• Pregnant women whose foetal ultrasound examination suggests that the foetus may have a chromosomal numerical abnormality

If a pregnant woman does not fall into any of the above categories, but has unresolved concerns about chromosomal abnormalities in the foetus and wishes to undergo NIPT, the pregnant woman’s own decision should be respected. We do not believe that it is medically relevant to have a high or low probability. We believe that it is preferable for all pregnant women to undergo screening with low risk.

NIPT testing methods and costs

The NIPT test procedure simply requires a blood sample to be taken from the pregnant woman after the doctor has examined her. The results of the test are known within one to two weeks after the blood sample is taken.

Basically, the genetic disorders that can be tested for with NIPT are 21 trisomy (Down syndrome), 18 trisomy (Edwards syndrome) and 13 trisomy (Patau syndrome). The Japanese Society of Obstetrics and Gynaecology recommends testing for all three at the same time. Some medical institutions can also test for chromosomal abnormalities other than the above three and determine gender.

NIPT is not covered by health insurance and the costs are entirely self-paid. As it is not covered by health insurance, the price can be set by the medical institution itself, but at most medical institutions, the cost of testing for the three recommended chromosome abnormalities is around JPY 150,000.

Hiro Clinic NIPT offers the N-Guard Tri Plan, which includes testing for 21, 18 and 13 trisomy and monosomy, for JPY 98,780 including tax. The clinic also offers a variety of tests to meet your needs, including a plan that includes microdeletion testing, which is rarely offered at other clinics.

It should be noted that the details other than the test content, such as pre-test counselling, interview by a doctor and follow-up, differ depending on the medical institution where the test is conducted. Hiro Clinic NIPT has obstetricians and gynaecologists on staff, who can provide a consultation on NIPT after receiving the results, but not all medical institutions have such a system in place.

Each NIPT provider has its own characteristics, so when choosing a provider, it is important not to compare prices alone, but to gather information on the tests that can be done for the same price and the follow-up services offered.

What are the risks of NIPT?

There are few risks associated with undergoing NIPT. The actual test only involves taking a blood sample from the mother. Therefore, it is said that there are few risks to both mother and child.

What to look out for when undergoing NIPT

It is important to note that NIPT is not a definitive diagnosis that confirms the baby’s DNA abnormality. NIPT is only used for screening to determine if there is a possibility of chromosomal abnormality, and if it is positive, an amniotic fluid chromosome test or trophoblastic test is required to confirm the diagnosis if there really is a chromosomal abnormality. If the result is positive, an amniotic fluid chromosome test or chorionic villus examination is required to confirm the diagnosis.

This is because even NIPT, which boasts higher accuracy than other testing methods such as the Early Pregnancy Combined Test and the Quattro Test, can still produce a small number of ‘false positives’.

Hiro Clinic NIPT provides a Positive Score Report, which combines a positive score and a positive predictive value. The Positive Score Report is only attached to positive results for trisomy 21, trisomy 18 and trisomy 13.

The positive predictive value is the probability that a positive diagnosis is indeed positive. Previous studies have shown that the positive predictive value increases with maternal age and gestational week. Furthermore, the positive predictive value varies depending on the chromosome being examined. From these three factors, it is possible to calculate a pregnant woman’s positive predictive value, i.e. the likelihood that she is indeed positive if she is diagnosed positive.

Of the 40,000 tests performed at Hiro Clinic NIPT, data from pregnant women who have had an amniotic fluid test is compiled to calculate the positive predictive value.

Patients with amniotic fluid test positive for trisomy 21 were 30 out of 32 NIPT-positive patients, with a positive predictive value of 93.75%. Patients with amniotic fluid test positive for trisomy 18 were 12 out of 16, with a positive predictive value of 75%. Three out of 10 patients with a positive amniotic fluid test for trisomy 13 had a positive predictive value of 30%.

Conversely, 70% of patients with a positive NIPT result for trisomy 13 had a negative amniotic fluid test. The negative rate is as high as 70%. If you choose to have an abortion based solely on a positive NIPT result for trisomy 13 without accurate knowledge, you could be making a wrong choice.

NIPT is a screening test, so it is dangerous to make a decision based on the results alone.

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NIPT counselling

Genetic counselling is an essential part of NIPT. Genetic counselling is a process in which a counsellor with specialist knowledge of genetics provides counselling to help resolve concerns and problems.

Hiro Clinic NIPT has specialists from the Japanese Society of Obstetrics and Gynaecology, prenatal consulting paediatricians and clinical genetic specialists on staff, who provide post-test consultations (genetic counselling) with the enrolled doctors. In addition to medical information about the test, psychological support is also available.

Summary

n this article, we explained the appropriate timing and method of testing for NIPT. The NIPT test is simple, requiring only a blood sample from the mother, and can determine with a high degree of accuracy and clinical research whether the baby has a possible chromosomal abnormality. The test can be taken from the time pregnancy is confirmed by ultrasound and is recommended up to around 14 weeks’ gestation.

The three common NIPT tests are 21 trisomy (Down syndrome), 18 trisomy (Edwards syndrome) and 13 trisomy (Patau syndrome), but the test content differs depending on the medical institution performing the test. In addition, as they are not covered by health insurance, the costs vary widely from medical institution to medical institution. Furthermore, there are also significant differences in follow-up services after the test.

If you are considering NIPT, please feel free to contact Hiro Clinic NIPT if you have any questions or concerns. We will help you undergo the test with peace of mind, with the latest information based on clinical research and after-sales support.

(Hiro Clinic uses the data as clinical research data only after obtaining your consent.)

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