The male to female ratio at birth

The human sex ratio (males:females) varies depending on when it is measured. The primary sex ratio is that present at fertilisation. The secondary sex ratio is that recorded at birth. The tertiary sex ratio is that of the sexually mature members of any particular population and the quaternary ratio is that of the surviving populace at post-reproductive age. This introduction and the subsequent papers in this collection will deal with the secondary sex ratio (M/F).
Source: Early Human Development - Category: Perinatology & Neonatology Authors: Tags: Introduction Source Type: research