In this unit we have looked at some of the factors which infuence a couple's decision to have a child. For people who choose not to do so, at least for some part of their lives, a range of contraceptive practices is available. We have looked at the biological processes involved in producing gametes, and at the precise sequence of events necessary to produce a healthy, fertilized egg. We have seen how this egg develops, first as a pre-programmed, free-living embryo, then becomes buried within its mother's tissues. We have looked at some of the effects that this has on the mother herself, and have glimpsed some of the physiological sacrifices that a mother must make for the sake of her baby. Finally, we put reproduction into a more social context, and looked at the ways in which cultural preferences for babies of a particular sex can be fulfilled to some extent by modern practices.