They are all part of an unprecedented storm of activity fueled by conservative legislators and aimed at restricting abortion access for millions of Americans. In a four-day span from April 26 to 29, 28 new restrictions were signed into law in seven states, the most antiabortion legislation to become law in a single week in more than a decade, according to a new analysis from the Guttmacher Institute, a nonprofit research center that supports abortion rights. As of April 29, the report found, there had been 536 abortion restrictions put forward across 46 states since January, with 61 of those bills being enacted. The volume of bills being proposed is historic, representing a new high water mark of antiabortion legislation, said Elizabeth Nash, who analyzes state policy for the Guttmacher Institute and co-authored the analysis.