Pregnancies with ‘double-positive’ multiple marker screening results: a population-based study in Ontario, Canada.

Multiple marker screening is offered to pregnant individuals in many jurisdictions to screen for trisomies 21 and 18. On occasion, the result is ‘double-positive’-a screening result that is unexpectedly positive for both aneuploidies. Although this occurs rarely, the paucity of available evidence about the outcomes of these pregnancies hinders patient counselling. This study aimed to investigate the association of double-positive results with preterm birth and other adverse perinatal outcomes.

Although rare, double-positive multiple marker screening results are associated with an increased risk of preterm birth and other adverse perinatal outcomes, even when excluding all identified chromosomal abnormalities.