Umbilical cord from and contains remnants of the yolk sac and allantois. It forms by the fifth week of development, replacing the yolk sac as the source of nutrients for the embryo. The cord is not directly connected to the mother's circulatory system, but instead joins the placenta, which transfers materials to and from the maternal blood without allowing direct mixing. The length of the umbilical cord is approximately equal to the crown-rump length of the fetus throughout pregnancy. The umbilical cord in a full term neonate is usually about 50 centimeters (20 in) long and about 2 centimeters (0.75 in) in
The Pregnant Widow The Pregnant Widow The Pregnant Widow is a novel by the English writer Martin Amis, published by Jonathan Cape on 4 February 2010. Its theme is the feminist revolution, which Amis sees as incomplete and bewildering for women, echoing the view of the 19th-century Russian writer, Alexander Herzen, that revolution is "a long night of chaos and desolation". The "pregnant widow", a phrase taken from Herzen's "From the other shore" (1848–1850), is the point at which the old order has given way, the new one not yet born. Amis said in 2007 that "consciousness is not revolutionised by the snap