Chaveeva P, et al. - Researchers examined a large series of pregnancies with a vanishing twin for multiples of the median values of serum free beta-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A). Further, they determined how these values associate with the interval between embryonic death and blood sampling and generated a model that would enable the incorporation of these metabolites in first-trimester combined screening for trisomy. In this retrospective study, they compared maternal serum free β-hCG and PAPP-A levels at 11–13 weeks' gestation in 528 dichorionic pregnancies with a vanishing twin vs those in 5,280 normal singleton pregnancies matched for method of conception and date of examination. The 528 dichorionic pregnancies with a vanishing twin comprised 194 pregnancies (36.7%) with an empty gestational sac and 334 (63.3%) with a dead embryo. Based on outcomes, they emphasize rely on a combination of maternal age, fetal nuchal translucency thickness and serum-free β-hCG for first-trimester screening for trisomy in pregnancies with a vanishing twin, as in singleton pregnancy, without the use of serum PAPP-A. Alternatively, the inclusion of PAPP-A can be considered but only after relevant adjustment for the interval between estimated gestational age at fetal demise and blood sampling.