Of the 535,000 women who died in childbirth or from pregnancy-related complications in 2005, 99% were in developing countries, according to another report by a group of UN agencies, including WHO, also out this week.

解答：

主体句式: 99% were in developing country.

结构分析: 这是一个复合句，由of构成的介词短语是句子主语的定语，该介词短语中有一个who引导的定语从句修饰名词women；according to构成的介词短语是句子的状语，在该状语中also out this week是report的补语。

句子译文: 而根据本周联合国机构（包括世界卫生组织）的一个组织的另外一个报道，2005年死于生产或怀孕相关并发症的53万5千名妇女中，99%是在发展中国家。