NPR's Joanne Silberner reports on a two-day meeting convened by the National Cancer Institute to talk about early events in pregnancy and the risk of breast cancer. Much of the meeting is closed to the public, and there's considerable discussion about abortion and the risk of breast cancer. The N.C.I. altered its scientific summary of the risks, changing its position that the risk is all-but-non-existent to a stance that science supports a risk. Critics charge that politics are influencing science on this topic, but opponents of abortion say the institute is finally interpreting the science correctly.