Comparisons to common produce frequently explain the growth of a developing baby, making the scale of early pregnancy more understandable. At 11 weeks of gestation, the developmental process reaches a significant turning point. The major structures are now fully formed, and the next phase of growth begins.
The 11-Week Size Comparison
At the beginning of the 11th week, the developing baby is commonly likened to the size of a fig or a large lime. The average length, measured from the crown of the head to the bottom of the rump, is approximately 4.1 centimeters (1.6 inches). The baby weighs very little at this stage, typically around 7 to 14 grams. This measurement method, called crown-rump length, is used because the lower limbs are still proportionally small and curled. This size marks the end of the first trimester’s initial rapid structural formation and the start of a period focused on growth and maturation.
Key Developmental Milestones
The 11th week is characterized by the refinement of structures formed during previous weeks. The fine webbing between the fingers and toes has disappeared, allowing for fully separate digits. The external genitalia are beginning to differentiate, though they are still too similar to be reliably identified on an ultrasound.
Inside the body, physiologic gut herniation completes as the intestines move back into the expanding abdominal cavity. Bone tissue is starting to harden in a process known as ossification, strengthening the cartilage framework of the skeletal system. The baby is also starting to make small, jerky movements, although they are too slight for the pregnant person to feel.
Defining the Embryo-to-Fetus Transition
The term used to describe the developing baby changes at this time due to a shift in biological status. The embryonic period, which is focused on organogenesis (the formation of all major organ systems), concludes at the end of the tenth week. The developing baby is now officially referred to as a fetus, a term that signifies the start of the fetal period.
This new stage, beginning at the 11th week, is primarily defined by rapid growth, size increase, and the functional maturation of the existing organs. The completion of the main structural blueprint is the agreed-upon criteria for this nomenclature change. Therefore, while a search query might use the term “embryo,” the 11th week technically marks the first week of the fetal stage of development.