" The expression "fee thulumaatin thalaathin," translated into English
as "a threefold darkness," indicates three dark regions involved during
the development of the embryo. These are:
a) The darkness of the abdomen
b) The darkness of the womb
c) The darkness of the placenta
As we have seen, modern biology has revealed that the embryological
development of the baby takes place in the manner revealed in
the verse, in three dark regions. Moreover, advances in the science of
embryology show that these regions consist of three layers each.
The lateral abdominal wall comprises three layers: the external
oblique, the internal oblique, and transverses abdominis muscles.91
Similarly, the wall of the womb also consists of three layers: the
epimetrium, the myometrium and the endometrium.92
Similarly again, the placenta surrounding the embryo also consists
of three layers: the amnion (the internal membrane around the foetus),
the chorion (the middle amnion layer) and the decidua (outer amnion
layer.)93
It is also pointed out in this verse that a human being is created in
the mother's womb in three distinct stages.
Indeed, modern biology has also revealed that the baby's embryological
development takes place in three distinct regions in the mother's
womb. Today, in all the embryology textbooks studied in departments
of medicine, this subject is taken as an element of basic knowledge.
For instance, in Basic Human Embryology, a fundamental reference
text in the field of embryology, this fact is stated as follows:
The life in the uterus has three stages: pre-embryonic; first two and a half
weeks, embryonic; until the end of the eight week, and fetal; from the
eight week to labor. "

― Harun Yahya , Allah's Miracles in the Qur'an