During pregnancy, how soon can the sex of the baby can be determined?
Although genetic sex (XX or XY) is determined at fertilization, the embryo’s gender is not distinguishable for the first six weeks of development; this is known as the indifferent period of development http://ibis-birthdefects.org/start/hermaphr.htm During the earliest development only examination of the chromosomes will tell us the (karyotypic) gender of the embryo. When the gonads appear at about the 6th post-conception week, they are neither testes or ovaries (i.e. they are “undifferentiated gonads”). But soon differences appear, triggered by the presence or absence of “testis determining factor” (TDF) which is protein coded for by the sry gene on the Y chromosome. http://academic.sun.ac.za/…/Life08.
