The SAFE Test is one of the most accurate non invasive prenatal tests to determine the chance of the presence of three most commonly screened for chromosomal conditions in pregnancy (T21, T18 and T13). It is the non invasive prenatal test with the lowest test failure rate, therefore many parents to be chose the SAFE test if there is an increased chance of test failure due to factors such as high maternal BMI.

Tiny structures inside your baby’s cells called chromosomes carry the genes that determine how your baby develops. There are 23 pairs of chromosomes per cell, however changes may occur during the production of sperm or egg cells which can lead to your baby having an extra chromosome. Although babies with Downs syndrome (T21), Edwards syndrome (T18) and Pataus syndrome (T13) are born to mothers of all ages, maternal age increases the likelihood of the presence of these conditions. The SAFE test analyses the cfDNA in the maternal blood, to determine if there is an increased likelihood that your baby has an extra chromosome present.

The SAFE NIPT is processed and analysed for The Birth Company by St Georges Hospital Laboratory in London. Due to the close proximity, most NIPT results are back within 7 calendar days. In some circumstances results can take longer.

Parents to be who wish to find out the likelihood that their baby has one of three chromosomal conditions; Down’s syndrome (T21), Edward’ syndrome (T18) or Patau's syndrome (T13) choose the SAFE Test. The TDL VeriSeq v2 by Illumina cfDNA test can be performed from 10 weeks of pregnancy, two weeks earlier than the NHS 11-14 week screening. The SAFE test has a greater sensitivity, specificity and higher positive predictive value (PPV) than the Nuchal Translucency screening, also known as the Combined Test. The SAFE cfDNA Test offers early reassurance and can reduce unnecessary anxiety and invasive testing caused by less effective prenatal screening methods.

SAFE is the only NIPT which offers prenatal screening for Vanishing Twin pregnancies. This is particularly important, as a Vanishing Twin pregnancy can affect the prenatal screening offered to you by the NHS. They may determine a likelihood for chromosomal conditions based on the Nuchal Translucency measurement at the back of your baby’s neck and your maternal age only (excluding the maternal hormone biochemistry, further reducing the sensitivity and the positive predictive value of the Nuchal translucency screening). For vanishing twin pregnancies the sensitivity is reduced to less than 95%. 

The Nuchal Translucency screening, or combined test, offered by the NHS determines a background chance based on maternal age. From the maternal age of 35 years of age onwards this background chance increases substantially. This increases the likelihood of receiving a high probability result from the Nuchal Translucency screening. Due to the limitation of the Nuchal translucency screening, this lowers the positive predictive value (PPV) of the test, meaning that those over 35 are more likely to receive a high probability result, even if the baby does not have the condition.

The SAFE test has a higher positive predictive value than Nuchal translucency screening. This means less high probability results where the condition is not actually present. We do not use the term false positives, as these are screening tests therefore they do not determine positives or negatives. They offer likelihoods.

The SAFE NIPT is particularly recommended for those over 35 years of age, parents to be who have had a high probability result in their current or previous pregnancy, or a confirmed chromosomal condition in a previous pregnancy. It is for those who wish to avoid unnecessary invasive testing, which carries a risk of miscarriage.

• An ultrasound scan is always performed prior to the SAFE blood test. This ensures that your baby is healthy, with a strong heartbeat and growing well. This scan will also confirm if it is a singleton or multiple pregnancy. Our specialist sonographer will check that baby is developing well and confirm your estimated due date, or EDD. Your baby must measure over 10 weeks gestation for the SAFE NIPT to be performed, therefore it may be best to wait until a few days past 10 weeks of pregnancy to visit us for your appointment to ensure your baby is developed enough.
• Our Specialist Sonographer will discuss the pros and cons of the three Non invasive prenatal tests available; TDL VeriSeq v2 by Illumina NIPT, Panorama NIPT or SAFE NIPT. This prenatal screening counselling will help you choose the best test for baby and for you.
• Once the pregnancy scan has been performed and your prenatal screening options discussed, a SAFE consent form will be given to you to read and sign. If you have any questions, are sonographers are here to answer them. Please find a copy of the SAFE consent form here.
• A simple blood test is then taken from the vein of the mother’s arm like any other blood test. There is no risk to your baby from having this blood test performed.
• The specialised SAFE cfDNA blood sample tube is packaged and dispatched to the laboratory for processing and analysis, with most samples arriving at the Laboratory within 24 hours.
• NIPT screening results determine if you have a low or high probability for Downs syndrome, Edwards syndrome or Pataus syndrome. As this is a screening test, the SAFE results are not positive or negative. The SAFE test report can also tell you the sex of your baby.
• If you receive a high probability result our expert team will discuss pathways, including further investigations such as detailed ultrasound scans, invasive testing, counselling or referral to your Fetal Medicine Unit (FMU). This can also be discussed with our Consultant.
• There can be circumstances where our Specialist Sonographers does not recommend the SAFE NIPT for your pregnancy. Each pregnancy is different. Other prenatal screening, diagnostic testing or further pregnancy care may then be recommended. Our Consultant provides support and advise where needed.

Please note We recommend using our pregnancy calculator, or contacting our specialist admin team if you are unsure of the best time to attend for your NIPT. NIPT can be performed from 10 weeks of pregnancy. If you are too early for NIPT when you attend for your appointment, an additional charge of £120 will be required to cover the cost of the additional appointment and scan required. 

Please note in the circumstance that during your appointment an ultrasound scan is performed but we do not proceed to the NIPT, a fee will be taken for the price of the scan. This can vary between £125 - £245 depending on gestation. The additional amount will be refunded to you.

Please note in the instance of a repeat full test failure, the SAFE test laboratory fees may be refunded. A fee for the appointment services provided will be retained.

• Results take from 5-10 calendar days depending on the day of week/time of day the sample is taken or if the lab need to perform further analysis on your blood sample. Results take an average number of 7 days.
• As soon as The Birth Company receives the SAFE laboratory results, we will call you to explain them before emailing you a copy to keep in your maternity notes. Our team are in the clinic from 8am to 8pm daily, and Saturdays and Sundays. The laboratory portals are checked throughout the day, but we do tend to receive most results in the late afternoon.

• Please note that the SAFE test requires one tube of blood. If the blood analysis is successful results are usually received within 5-7 days.

  If the blood analysis from the first attempt is not successful, the lab will call a ‘No Result Test Failure’ We will invite you to return to the clinic for a rescan and a new blood draw. We always recommend a rescan in these circumstances as baby’s are developing at a rapid rate during early gestations. 

• In rare circumstances the result can take longer than 10 days. We understand it can be a stressful time waiting for results and we will endeavour to communicate any delays to our patients as soon as we receive information from the laboratory.

• The SAFE NIPT report will determine whether you have a low probability or high probability for Down’s Syndrome, Edwards’ Syndrome or Patau’s Syndrome (Trisomy 21, Trisomy 18 or Trisomy 13). This can be particularly reassuring if you have received a high probability Nuchal translucency scan, or a sonographer has found a structural condition such as Renal Pelvis Dilatation or short femurs at your 20 week anomaly scan.
• If you receive Low probability results, the likelihood of your baby having each of the conditions is less than 1 in 10’000. This means that we would expect less than one baby to be born out of ten thousand births with the condition Down’s syndrome, Edwards’ syndrome or Patau’s syndrome. The result is not positive, nor negative as this is screening test only.
• If you receive a High probability result, this will specify which trisomy condition there is a high probability of your baby having; Downs syndrome, Edwards syndrome or Pataus syndrome. This is not a positive result, this does not confirm that your baby has this condition, as this is a screening test only.
• Please note that the positive predictive value (PPV) for NIPT varies between Downs syndrome, Edwards syndrome and Pataus Syndrome, between pregnancies and with maternal age. The PPV for Downs syndrome varies from 1 in 2 babies confirmed to have the condition to 9 in 10 babies confirmed to have the condition, therefore genetic counselling, further investigation and a supportive pregnancy pathway is recommended. During pregnancy, the only method available to diagnose if the condition is actually present is invasive testing such as chorionic villus sampling (CVS) or amniocentesis.
• Due to the nature of the SAFE test, there is a 2% chance of receiving No Result from your NIPT blood sample. This is not a low probability, nor high probability. This happens in around 2 in 100 samples, this does not mean that your baby has a condition present. It is most commonly because the SAFE blood sample did not contain more than 2-4% Fetal Fraction, which is the minimum quantity of cf DNA needed to perform an accurate SAFE NIPT analysis, In most cases it is suitable to offer a redraw of the sample free of charge, including an ultrasound scan. The chance of receiving a screening result on the second draw is 50%. No Result is increased by maternal weight greater than 85kg, as evidence supports that there is a negative relationship between maternal weight and the quantity of cfDNA fetal fraction.
• If you have selected the option of finding out the sex of your baby, this will also be documented on the NIPT report. In some circumstances, SAFE are unable to perform sex determination analysis.

SAFE Test Low Probability Example Report

SAFE Test High Probability Example Report

There is an increased likelihood of test failure for IVF pregnancies, twin pregnancies, mothers using blood thinners and mothers weighing over 85kg. Test failures can cause parents unnecessary concern.

If possible we recommend waiting until 11 or 12 weeks (or later) to perform your NIPT, this will increase the percentage of fetal fraction available for the test and reduce the likelihood of receiving no result.

Prior to this advance in prenatal screening, doctors and screening midwives used the results of the Nuchal Translucency Scan to advise parents to be if they had a low or high probability of their baby having the conditions Downs syndrome, Edwards syndrome or Pataus syndrome.

The Nuchal Translucency Scan is a method of screening offered by the NHS from 11 to 14 weeks of pregnancy and includes several factors to determine this probability, including maternal age, the nuchal translucency measurement at the back of the baby’s neck and the maternal blood biochemistry (free ß-hCG and PAPP-A). This method is also known as the combined test. The greater the maternal age, the greater the background chance of the presence of the condition.

Nuchal Translucency screening test, or combined test, has a sensitivity of 84%. Parents to be who receive a high chance result are offered counselling by their screening midwife. This does not confirm the presence of the chromosomal condition. A diagnostic invasive test such as chorion villous sampling (CVS) or amniocentesis can confirm the presence or absence of the conditions Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. A needle is used to take a sample of the pregnancy, through the mother’s tummy to allow for the analysis of fetal DNA. These invasive tests report a risk of miscarriage to the pregnancy of 1:100.

Since SAFE Non invasive prenatal testing (NIPT) became available many parents to be chose this more accurate prenatal screening. For comparison, when screening for Down’s syndrome using the Nuchal Translucency scan, the detection rate is 84% and positive predictive value (PPV) is less than 15%, meaning the actual number of high probability pregnancies that are later confirmed to have the condition Downs syndrome is less than 1 in 6.

When screening for Down’s syndrome using the SAFE Non Invasive Prenatal Test, the detection rate is 99% and positive predictive value (PPV) varies from 48% to 99% depending on maternal and pregnancy factors, including maternal age and the presence of an increased nuchal translucency measurement. The greater the maternal age, the greater the NIPT positive predictive value (PPV). You can use the NIPT Positive Predictive Value calculator here to calculate your PPV for each condition here:

NIPT Predictive Value Calculator 

This means using SAFE NIPT, the actual number of high probability pregnancies confirmed to have the condition Down’s syndrome vary from 1 in 2 (50%) confirmed with the condition to 9 in 10 (90%) of babies confirmed with the condition, depending on maternal age and other factors.

For Edwards Syndrome the SAFE NIPT positive predictive value (PPV) is 2 in 5, or 40% likelihood that the baby is confirmed to have the condition. For Pataus Syndrome the SAFE NIPT PPV is reported as 1 in 2, or 50% of babies confirmed to have the condition after a high probability SAFE NIPT.

The results of the SAFE NIPT blood test has a high detection rate which will hugely reduce the need for unnecessary invasive testing by CVS or amniocentesis. This is great news for parents to be looking for reassurance in pregnancy.

It is important that an ultrasound scan is performed just before the blood test to confirm the pregnancy, and to check if there are twins or more. Our specialist sonographers will perform a detailed early fetal scan, early anatomy scan or anatomy scan depending how many weeks pregnancy you are when you visit us for the SAFE Test.

Yes. Structural conditions such as brain, face, stomach, kidney, bladder and limb conditions, as well as Spina Bifida. Poor growth and development will only be demonstrated on ultrasound scans, often not until the second and third trimester. If you would like further reassurance that your baby is developing and growing well, our specialist sonographers are trained to perform early anomaly scans from 16 weeks of pregnancy.

Many miscarriages of pregnancy are caused by chromosomal conditions, therefore there is a high probability that there was a chromosomal condition present in the twin that has sadly passed. There is an increased likelihood of receiving a high probability result when a demised twin is present. Some evidence suggests that performing Non Invasive Prenatal Testing 8 weeks after the demise of the second twin may reduce the likelihood of a false positive result. 

A high probability result does not confirm the presence of a chromosomal condition in the live twin, only invasive testing can prenatally confirm or exclude chromosomal conditions.

The SAFE Non-Invasive Prenatal Test is unable to offer sex determination for vanishing twin pregnancies. 

If you are looking for a second opinion, please ensure that you provide us with your relevant ultrasound report ahead of your appointment to ensure that we can provide you with the best service. 

Ultrasound reports should be sent to bookings@thebirthcompany.co.uk

The SAFE Test, including an ultrasound scan and prenatal screening counselling from our Specialist Sonographers costs £500.

Appointments after 5pm, weekend and bank holiday appointments incur a £50 surcharge. 

The SAFE NIPT has a turnaround time of approximately 7-10 days this is due to the samples being processed in London (Please note in some circumstances results can take longer). Parents to be who have received high probability Nuchal Translucency screening result, or if the sonographer has found a condition present on ultrasound appreciate receiving results as soon as possible to provide reassurance, and to help plan their pregnancy pathway.

If the NIPT is low probability then it is important that the sonographer or doctor performing the 12 week scan or 20 week pregnancy scan is aware of this. If the test is high probability then you should return to The Birth Company or your NHS Fetal Medicine Unit for further counselling and to develop a supportive pregnancy pathway. 

Pregnant women are offered two routine ultrasound scans during pregnancy within the NHS, this is called the Fetal Anomaly Screening Programme 

Depending on how many weeks pregnant you are, we recommend you take the opportunity to have a 11 to 14 week pregnancy scan privately or with the NHS. The focus of the 11 - 14 week scan will change as you will already know if you have a low chance for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. The 11 to 14 week pregnancy scan will look at the development of your baby in detail, our Sonographers are highly trained to perform early fetal scans and early fetal anomaly scans. These specialist private pregnancy scans and NHS scans look for structural conditions (these may exist without the presence of a chromosomal condition).

The other routine pregnancy scan offered by the NHS is around 20 weeks of pregnancy called the Anatomy scan. The purpose of this ultrasound scan is to assess your baby’s physical development and to look for 11 rare conditions, including head/brain and heart conditions. The 20 week anomaly scan is a very important ultrasound scan during pregnancy.

The Harmony Test NIPT was the first NIPT available privately in the UK. This test was processed by The Doctors Laboratory (TDL UK).

Since September 2023 TDL are no longer offering the Harmony NIPT. They have replaced the Harmony NIPT with Veriseq v2 by Illumina NIPT.

This newer NIPT technology promises faster turnaround times, often as quickly as 2-4 days and lower test failure rates. We welcome this new technology, improving your pregnancy journey.

More information about chromosomal conditions can be found here:

• Downs Syndrome Association
• SOFT UK
• Patau's Syndrome 
• Edward's Syndrome 

More information about screening tests offered in pregnancy can be found here:

• Screening tests for your and your baby
• Screening tests for you and your baby translated versions