What are the stages of human prenatal development?

In the history of embryology, preformationism was a theory of generation widely accepted from the late seventeenth to the late eighteenth century. Contrary to the theory of epigenesis (the gradual emergence of form), preformationists held that the unborn offspring exists fully formed in the gametes of its parents prior to conception. They argued that the fertilized egg, although apparently formless and unorganized, contains a complete set of adult organs and characteristics that are too small to be seen. Thus, what appears to be the de novo formation of tissues, organs, and other structures is, in fact, merely an increase in size. Although preformationism emerged as a fully developed doctrine only in the seventeenth and eighteenth centuries, related ideas appear earlier in the writings of Galen, who suggested that the embryo exists fully formed within the male semen and simply enlarges during development.¹

However, unlike the ancient preformationist tradition, the Qurʾān alludes to epigenesis in that it states that Man is created through successive stages in the mother’s womb. Allāh says: {He creates you in the wombs of your mothers ˹in stages˺, one development after another} (Qurʾān 39:6). Just as the Qurʾān points out that the human being is created in the womb in distinct stages, modern biology has likewise identified three principal stages of prenatal development: the germinal, embryonic, and fetal stages. The first two weeks after conception constitute the germinal stage; the period from the third through the eighth week is known as the embryonic stage; and the time from the ninth week until birth is called the fetal stage. Today, this classification is regarded as basic knowledge in embryology textbooks used in medical education. Modern embryology itself is a relatively recent development, beginning with the invention of the microscope in the seventeenth century. Yet the recognition that the human being develops through successive stages in the womb emerged only much later. Nevertheless, the Qurʾān and the Sunnah provide a description of the major events in human prenatal development—from the stage of gametes and conception to full-term pregnancy and birth. Much of this knowledge became accessible only through observations made possible by modern instruments. Yet, as with many other scientific realities, Allāh draws attention to them in the verses of the Qurʾān. The presence of a coherent description of the step-by-step stages of prenatal development in the Qurʾān, at a time when medical knowledge was extremely limited, is powerful evidence that it is the Word of Allāh. For who else could have conveyed this knowledge to Prophet Muḥammad (PBUH) except the Creator Himself, Who says: {He creates you in the wombs of your mothers ˹in stages˺, one development after another} (Qurʾān 39:6).