There are certainly differences early on: singleton babies conceived by IVF or ICSI are more likely to have a low birthweight and to die soon after birth (New Scientist, 23 October 2004, p 10). Could these problems have something to do with the process of IVF or ICSI, such as growing the embryos in a dish for two to five days? Growth media have been developed by trial and error, and contain only a few amino acids and other nutrients. They have been kept simple in the hope of avoiding unanticipated effects.
Yet according to Sarah Robertson's team at the University of Adelaide, at least one growth factor is needed. Her team compared the fate of three groups of mouse embryos: embryos conceived naturally and flushed from the mother's body; IVF embryos grown in a normal culture medium; and IVF embryos grown in a medium containing a growth factor called GMCSF, which a range of mammals produce, including humans. The placentas of the mouse embryos grown without GM-CSF were smaller and the pups' birthweight lower compared with the embryos conceived naturally. By adulthood, these mice had grown fatter than the other mice, and the males also had smaller brains.
Adding GM-CSF to the culture medium almost completely eliminated these differences, the team will report in the journal Endocrinology. The differences between all groups were relatively small, cautions IVF expert Alan Handyside of the University of Leeds in the UK. And even if the results do stand up, it is not clear if mouse studies are rel