Pre-implantation genetic analyses are typically carried out on growing, multicellular embryos. Hou et al. fertilized single human oocytes and extracted the polar bodies, which are products of maternal meiosis that are dispensable for embryonic development. They carried out DNA amplification by multiple annealing and looping-based amplification cycles (MALBAC) followed by high-throughput sequencing of the polar body genomes. From these data, they were able to deduce the presence or absence of chromosomal aneuploidies and single-nucleotide disease variants in the unsampled female pronucleus, which forms the maternally inherited component of the embryonic genome.