High-Risk Trisomy 18 NIPT → Normal Baby - My Story
Hi everyone 🤍 I’ve been waiting to write this until I had final answers, because posts like this were what got me through some of the hardest months of my life.
If you’re here because you just got a high-risk NIPT — I see you. I was you.
I’m 37 and my NIPT came back as High risk for Trisomy 18
No prior concerns. No warning. Just that result. I just wanted to know the gender! With my first daughter, I never did the NIPT(I was younger and it wasn’t suggested since I wasn’t advanced maternal age). My OB called and pretty much said these tests are 99% accurate unfortunately. Gave us no hope.
It completely unraveled me.
I immediately went into research mode, but what I didn’t fully grasp at first (and what matters so much): • NIPT is a screening test, not diagnostic • It analyzes placental DNA, not directly fetal DNA • False positives can occur, most commonly due to confined placental mosaicism
Some things to note. My PPV was 52% after talking with genetics counselor about a week after getting the NIPT result. I held onto that 48% so much. My fetal faction was 3.5% but I was also on lovenox since I was 5 weeks pregnant (I have a blood clotting disorder). It was also noted later that I had a marginal cord insertion which can play into NIPT results based on my research.
She told us about confined placental mosaicism so we knew we didn’t want to do the CVS and decided to wait until I could do the amnio.
However, I struggled with the idea of doing the amnio as I was still nervous of miscarriage. I figured shoot, if we were the one in whatever thousands who had a high risk for T18 - with my odds on anything anymore - an amnio would cause a miscarriage! That was my thought at the time because I truly didn’t believe that we would be lucky in any way anymore - that was how low I was feeling.
Also, if we did do an amnio and it showed true T18 - I wouldn’t have terminated either - so we wanted to hold onto baby girl however long the Lord wanted me to carry her.
We chose not to pursue amniocentesis and instead followed closely with Maternal Fetal Medicine and over the course of my pregnancy - each ultrasound was with MFM. Those doctors were amazing and I started to have more hope with each normal ultrasound.
My scans were normal. Starting with NT scan.
• NT scan → normal
• Early anatomy at 16 weeks → normal
• 20-week anatomy → normal
• Fetal echocardiogram (doctor suggested this for peace of mind even more so) → normal
• Serial growth scans → appropriate growth (approx. 30–70th percentile)
I also was having consistent, strong fetal movement - I think I even felt it earlier than my first since I had a posterior placenta.
Something that triggered my anxiety:
Late in pregnancy, head circumference percentiles trended lower. I would spiral and I put every report into chat GPT to get feedback on what we saw. Which in hindsight - I should have just trusted the docs when they didn’t have concerns but my anxiety was still spiraling a lot.
But clinically:
• Ratios (HC/AC) remained normal
• No structural abnormalities were ever identified
• No soft markers for T18
• MFM specialists were not concerned
The Psychological Reality
Even with normal imaging, I could not fully let go of: • “What if it’s mosaic trisomy 18?” • “What if ultrasounds are missing something?” • “What if we find out at birth?”
This is something I want to say clearly because I still struggled so so much with to this - Normal scans do not always calm anxiety after a high-risk NIPT
Your brain holds onto the initial threat. I felt like I was holding my breath every day and waiting for shoe to drop.
We were then scheduled for a repeat c section at 38 weeks 6 days. We decided we would do cord blood testing at birth.
Well, our little one decided to make an early entrance and my water broke at 38 weeks, 4 days.
On the way to hospital I was eager to meet her but also nervous as heck and worried that we would see some abnormalities at birth - that was still my fear.
We even met with NICU team before as they asked about what type of care we would like should she have Trisomy 18. It was hard to get it out and say out loud because we had faith it would all be ok - but we told them we would want palliative care and spend as much time with her as possible and have her be comfortable - but not in pain - we still held onto the good scans and had faith that she would be healthy.
My faith was tested during this whole period and I will say I did get closer to God during this time. I know that might not be the case for most people but I did rely heavily on my faith.
Delivery & Her Assessment
• Apgars: 8 / 9 / 9
• Normal tone, cry, and transition
• Feeding, voiding, stooling appropriately
• No dysmorphic features
• Normal pediatric exam
The Pediatrician’s exact words:
“If I didn’t know about the NIPT, I would never suspect Trisomy 18.”
She was here and she looked and was acting normal!
Postnatal Genetic Testing (Definitive)
Given the NIPT, we pursued full diagnostic testing for her cord blood testing
Karyotype (Chromosome Analysis) • Result: 46,XX (NORMAL) • No trisomy 18 • No structural chromosomal abnormalities
Cytogenomic SNP Microarray • Result: NORMAL • No copy number variants (CNVs) • No clinically significant deletions or duplications • No regions of concern
These two tests together: • Evaluate both whole chromosomes and submicroscopic changes • Effectively rule out clinically meaningful trisomy 18, including mosaicism at relevant levels
Final Outcome
About 2 weeks after her birth, we got microarray back and we have a healthy baby girl with completely normal genetic testing.
This was a false positive NIPT for Trisomy 18
For anyone in this situation: • A high-risk NIPT for T18 is not a diagnosis
• Confined placental mosaicism is a well-documented cause of false positives - we didn’t get my placenta tested but I do wonder if it was CPM. we will never know I guess
I lived for months thinking:
“I will not be able to breathe until I have final proof.”
And even after birth, I needed the genetic reports to fully release the fear.
If that’s you: You’re not irrational You’re not overreacting You’re a parent trying to protect your child
There is an end to this process.
And sometimes — even after a devastating screening result — the ending is a healthy baby!
If you’re in the middle of this, I’m holding space for you 🩷 You are not alone.