If only a few firms compete in a given product market, if the market is difficult to enter and if all leading firms adopt selective distribution, then competition between brands will not keep prices down and consumers will suffer.

ECONOMIST: Vertical restraints: Selective selling | The

This was partly due to patients wanting to maximise their chances of a quick pregnancy to keep costs down, and partly due to competition between doctors, keen to gain a reputation for good results.

BBC: Extra embryo 'risks baby health'