The human foetus after 2-3 months, showing the umbilical cord spiralling above the body of the foetus. The umbilical cord carries arteries & veins that provide a 2 way exchange of nourishment (ie oxygen) & waste products between the foetal & maternal circulation. The cord is joined to the foetus at the abdomen (the navel) and to the uterine membrane at the placenta, which forms an interface between the 2 circulations. The placenta does not act merely as a filter for the foetus, but as a multiple organ system: it also supports the mother's body functions by synthesising a range of hormones (in a similar way as the pituitary gland does).