the one area where there is, on balance, a consensus is the need to identify serious defects in a foetus before birth. this is now routine in many countries. the definition of "serious" would certainly include defects which make life of the foetus (if born) so defective that its life would be troubled and short. some conditions, like triple-21 down's syndrome, are often not that serious. in many cases, the parents' wishes decide whether or not an abortion will be carried out.