摘要：Although considered mainly as prob- lems of the developing world, maternal mortality and morbidity remain a chal- lenge in the United States of America (USA). 1 Between 1990 and 2013, the maternal mortality ratio for the USA more than doubled from an estimated 12 to 28 maternal deaths per 100 000 bir ths 1 and the country has now a higher ratio than those reported for most high-income countries and the Islamic Republic of Iran, Libya and Turkey. 2 About half of all maternal deaths in the USA are preventable.
