Serial first- and second-trimester Down's syndrome screening tests among IVF-versus naturally-conceived singletons

Area of Science:

• Prenatal screening and diagnostics
• Reproductive medicine
• Maternal-fetal medicine

Background:

• Assisted reproductive technologies (ART) may influence biochemical markers used in prenatal screening.
• Previous reports suggest a potential for increased false-positive rates in second-trimester screening for pregnancies conceived via ART.

Purpose of the Study:

• To compare the accuracy and false-positive rates of Down's syndrome screening between naturally conceived and in vitro fertilization (IVF) pregnancies.
• To evaluate the impact of IVF on first- and second-trimester serum markers and screening outcomes.

Main Methods:

• A comparative study involving 285 naturally conceived and 71 IVF-conceived singleton pregnancies.
• Utilized first-trimester combined screening (nuchal translucency, free beta-HCG, PAPP-A) and second-trimester triple serum screening (AFP, intact HCG, uE3).
• Analyzed serum marker levels and false-positive rates after excluding aneuploidies, miscarriages, and anomalies.

Main Results:

• No significant difference in nuchal translucency (NT) measurements between groups.
• IVF group showed lower PAPP-A and higher AFP levels compared to naturally conceived group.
• Significantly higher second-trimester false-positive rate (FPR) in the IVF group (10% vs. 5%, P=0.029), leading to increased amniocentesis rates.

Conclusions:

• In vitro fertilization pregnancies exhibit a higher second-trimester false-positive rate in Down's syndrome screening.
• Integrated screening approaches or sole reliance on nuchal translucency (NT) may mitigate this increased FPR and warrant further investigation.