What Is a Blastocyst — and Why Do Day 5 Embryos Matter in IVF Surrogacy?
Understanding embryo development stages is key to IVF surrogacy. Around day five many embryos reach the blastocyst stage — a milestone that influences implantation and pregnancy outcomes. This article explains what a blastocyst is, why day‑5 embryos are often favored, and how egg donation can affect embryo quality. Throughout we reference IVF surrogacy to give intended parents concise, evidence‑based insight into the choices they may face.









