IVF embryo selection

In IVF, several embryos are typically available before transfer. A biopsy removes a few cells from each, and sequencing checks for chromosomal errors (aneuploidy) that cause miscarriage or conditions like Down syndrome. That diagnostic use is well-established. The contested frontier is polygenic screening: scoring embryos on trait-linked SNPs to rank them by predicted height, IQ, or disease risk. The hard part is that polygenic scores carry wide confidence intervals, transfer one embryo at a time, and the gain over random selection in a typical IVF cohort is small — often swamped by chance and environmental variance.