ABSTRACT
Following the fertilisation of an egg by a sperm, a single cell structure is formed called a zygote which contains mixed maternal and paternal genetic material. After travelling down the Fallopian tube and undergoing a number of cell divisions over about eight days, a ball of cells called a blastocyte is formed; this may or may not implant into the uterus; many in fact don’t. If plantation occurs, the embryonic stage of development begins from the fifteenth day after conception. The most sensitive time for the development of the central nervous system is from three to 16 weeks after conception (Moore and Persuad 1998). Rapid brain development is seen from weeks 25 to 28 such that a premature baby born at this time may possibly survive. Birth is normally at around 40 weeks. The brain is far from being ready for separate existence at this point, but remaining in the womb until all networks are ready to go would extend pregnancy to around 24 months (Gould 1977). Carrying and delivering a baby of such size would be highly problematic! Childbirth is already frequently traumatic.
