Obstetric Outcomes Following a Failed NIPT at an Irish Tertiary Maternity Centre**

Shah A, Cooley S, Daly S
Rotunda Hospital, Dublin
Royal College of Surgeons in Ireland, Dublin

Background

• Non-invasive Prenatal Testing (NIPT) offers screening for foetal chromosomal abnormalities such as; Trisomy 21, 13, 18 and Monosomy X.
• This test analyses cell-free foetal DNA in maternal blood and offered after the 9th gestational week.
• Fails in 1-3% of tests due to low fetal fraction, influenced by factors like early gestational age, high maternal BMI, placental insufficiency, or multiple pregnancies, or may be linked to future obstetric implications.

Aim: To investigate obstetric outcomes in women who failed to obtain NIPT results from 2021 to 2023.

Method:Retrospective cohort study comparing maternal characteristics and obstetric outcomes who failed NIPT at the Rotunda Hospital to general Irish obstetric population.

Results:

• Total 5,525 NIPTs performed at the Rotunda Hospital from 2021 to 2023.
• 2.7% failed to yield a result
• Gestational Diabetes Mellitus (GDM) in 29.7% of this population
• Hypertensive disorders occurred in 10.8%
• Chromosomal aneuploidies discovered in 7.4% of pregnancies
• Mean BMI 29.8 kg/m2 and average maternal age 37.1 years.

Discussion:

• We found significantly higher rates of Gestational Diabetes Mellitus (29.7% vs. 12.4%) and Hypertensive Disorders of Pregnancy (10.8% vs. 5.9%) compared to the general Irish obstetric population, suggesting an intrinsic link between test failure and adverse outcomes. (Fig. 1)
• Elevated BMI (mean 29.8 kg/m²) and advanced maternal age (mean 37.1 years) likely compounded risks for both NIPT failure and complications.
• A failed NIPT result may signal placental dysfunction, making it a potential early marker for maternal and fetal risks.

Results:

A failed NIPT result is more than a technical issue - it may serve as an early warning for maternal and foetal complications.
Recognising this link enables targeted monitoring, timely intervention, and improved pregnancy outcomes.