根据以下材料，回答题 U.S. to Start $3.2 Billion Child Health Study in January A study that will cost $3.2 billion and last more than two decades to track the health of 100，000 U.S. children from before birth to age 21 will be launched in January， U. S. health officials said on Friday. Officials from the U. S. government's National Institutes of Health said they hope the study， to be conducted at 105 locations throughout the United States， can help identify early-life influences that affect later development， with the goal of learning new ways to treat or prevent illness. The study will examine hereditary and environmental factors such as exposure to certain chemicals that affect health. Researchers will collect genetic and biological samples from people in the study as well as samples from the homes of the women and their babies including air， water， dust and materials used to construct their residences， the NIH said. Officials said more than $200 million has been spent already and the study is projected to cost $3.2 billion. 'We anticipate that in the long term， what we learn from the study will result in a significant savings in the nation's health care costs，' Dr. Duane Alexander， who heads the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development， told reporters. The study will begin in January when the University of North Carolina and the Mount Sinai School of Medicine in New York start signing up pregnant women whose babies will then be followed to age 21. Some of the early findings will be about factors behind pre-term birth， which has become more common in recent years， according to Dr. Peter Scheidt of the NIH， who heads the study. The people taking part will be from rural， urban and suburban areas， from all income and educational levels and from all racial groups， the NIH said. The aim of the study is to find new ways to __________. 查看材料