When does phenogenesis occur during fetal development?

Phenogenesis, which refers to the "attainment of final form," occurs during fetal development between days 57 and 266 of gestation.1

While major malformations typically arise during the earlier stages of blastogenesis and organogenesis, phenogenesis is the period associated with the development of minor anomalies—subtle structural or appearance-based defects. During this phase, the fetus undergoes significant growth, the maturation of various cell types, and the functional development of organs, alongside the acquisition of individual physical attributes.1