First-trimester Down syndrome screening following assisted conception

To the Editor:

We would like to comment on the article written by Dr. Bellver and colleagues (1) regarding the need for adjustments of first-trimester Down syndrome screening parameters following assisted conception. Although we greatly appreciate their work, which confirms earlier data in the field, we would like to issue some additional remarks.

The Bellver et al. study suggests a reduced maternal serum pregnancy-associated plasma protein A (PAPP-A) and increased false positive rates (FPR) in singleton pregnancies achieved by in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), compared with naturally conceived pregnancies. However, the latter showed to be significant when including only ICSI cycles using non-donor oocytes. The authors discuss several other groups according mode of conception (IUI with partner or donor sperm, IVF, non-donor versus donor oocytes, fresh versus frozen embryo transfer), which veils the main message of the article, namely that (at least in their cohort) only in ICSI non-donor cycles serum PAPP-A level at first-trimester Down screening is significantly different from that seen in natural pregnancies. In their manuscript the authors describe a « diminished » PAPP-A level, even in cases where these levels are not significantly different, which is confusing.