Although in vitro fertilization (IVF) success rates have improved over the past decade, multiple pregnancies have become a formidable problem. The solution to this problem seems simple by mandating the reduction in numbers of embryos transferred. However, this is typically not accomplished without a compromise in the pregnancy rate. There have been a number of approaches designed to address high order multiple pregnancies from multi factorial analysis of early cleavage stage embryos to the development of extended culture systems, both of which require manipulations in the culture environment. Manipulations in embryo culture environment may not be benign. Several studies have demonstrated that adverse culture conditions have effects on gene expression and imprinting. Studies have also demonstrated that singleton human IVF babies have lower birth weight and higher incidence of congenital anomalies than natural conception babies. All of these factors need to be considered in relation to long term viability of IVF babies and the Barker hypothesis.