Making Sense of a Prenatal Detection of Trisomy 16 Mosaicism in the Placenta: A Qualitative Study of Pregnant Women's Decision Making.

Objective: Prenatal detection of Trisomy 16 mosaicism (MosT16) in a Chorionic Villus Sample (CVS) results may cause significant anxiety for expectant parents due to the risk of fetal malformation and fetal growth restriction (FGR). The aim of this study was to investigate the experiences and decision-making of women receiving a MosT16 results during pregnancy.

Methods: In-depth, semi-structured interviews with eight Danish women who received a MosT16 CVS results. Interviews were analyzed using reflexive thematic analysis.

Results: Four women terminated pregnancy following the MosT16 CVS result, emphasizing the emotional burden of waiting for amniocentesis and concerns about fetal involvement and FGR risk. Four women opted to await amniocentesis following which one terminated pregnancy due to fetal involvement, while three continued their pregnancies (one normal result, two low-percentage fetal involvement results). During pregnancy, all three fetuses were small for gestational age, and the concerns about their growth were burdensome for expectant parents. Two women delivered prematurely, but all three described their babies as healthy.

Conclusion: The prenatal MosT16 CVS result represents a critical decision point, requiring consideration of both fetal involvement and FGR risk. Thus, genetic counseling should be combined with counseling from obstetrics/fetal medicine specialists.