BERLIN — Yong-Hee Kim still can't believe that in a prosperous country like Germany, powdered baby formula would ever be rationed and she would have to scour shops in Berlin to find the right brand for her 13-month-old son.

But that's what has happened since major retailers in Germany this year began limiting sales of leading brands of baby formula. Parents in Britain, the Netherlands and Hong Kong have faced similar restrictions.

The reason for the sudden shortage is a quirk of globalization — one that illustrates the complexities of supply and demand in a wired world.

Parents thousands of miles away in China have been using the Internet or tapping friends and relatives in Europe to buy up stocks of high quality European-produced formula — often paying much higher prices than they would here.

Chinese demand for foreign brands soared after drought in Australia and New Zealand cut supplies from China's major sources of imported baby formula. Chinese parents who have enough money have largely shunned local brands since a contaminated milk scandal in 2008 left six babies dead and another 300,000 sick.

With Chinese consumers turning to sources abroad, major retail outlets in Germany, Britain, the Netherlands and Hong Kong have limited sales of several leading brands of baby formula.