The terms “embryo” and “fetus” are often used interchangeably, leading to confusion and misconceptions. Understanding the distinction between these two stages is vital for anyone navigating the early stages of pregnancy.
By clearly differentiating between an embryo and a fetus, you can better grasp the development process and your IVF timelines.
You can learn more information here if you’re unsure about the differences between embryos, fetuses and zygotes. Additionally, if you’re considering surrogacy, we can assist you in finding a potential surrogate.
Contact us online, and we’d be happy to help when you’re ready to begin the journey.
Embryo vs. Fetus: What’s the Difference?
To clarify the differences between these two developmental stages:
An embryo is a fertilized egg that has initiated cell division and development. After the egg and sperm unite in a laboratory setting, the resulting fertilized egg, called a zygote, begins to divide and form an embryo. A fetus represents a later stage of development, occurring from the end of the eighth week of pregnancy until birth. This stage is marked by rapid growth, the development of complex body functions, and the emergence of recognizable human features.
The key distinction lies in the formation of organs and bodily systems; by the fetal stage, many of these systems have already developed.
Zygote vs. Embryo: What’s the Difference?
A zygote is a single-cell organism formed from a fertilized egg. As it develops, the zygote divides to become a blastocyst, which eventually forms the embryo and placenta. In this sense, the zygote can be viewed as an early form of the embryo.
When Does an Embryo Become a Fetus?
The first ten weeks of pregnancy are crucial for understanding the transition from embryo to fetus. Let’s break it down week by week:
Ovulation occurs when an egg is released into the surrogate’s fallopian tubes. If successful, sperm fertilizes the egg, forming a zygote. Implantation takes place. After fertilization, the zygote divides and becomes a blastocyst, traveling down the fallopian tubes into the uterus. If implantation is successful, the surrogate’s body produces human chorionic gonadotrophin (hCG), known as the “pregnancy hormone.” The embryonic period officially begins. The embryo now consists of three layers: Ectoderm (future skin, eyes, inner ears, nervous system and connective tissue), mesoderm (future bones, muscles, reproductive system) and endoderm (future lungs, bladder, intestines). The embryo starts developing basic facial features along with budding arms and legs. At this stage, it is approximately the size of a pomegranate seed and has formed a tube of cardiac cells that pump blood and emit electrical impulses. The brain and head continue to develop, with arms and legs growing more noticeably. The nostrils and eye lenses also begin to form. The ears and eyelids develop further, while the nose and upper lip start taking shape. The future baby’s arms can now bend at the elbow, and toes are forming. The eyelids and ears become more refined. The embryonic period concludes as many bodily systems develop. From this point onward, the fetal stage begins.
If you’re interested in learning more about surrogacy, feel free to fill out our online contact form at any time. We’re here to support you every step of the way.