Louise Slaughter, a liberal Democrat who represented an upstate New York district in Congress for more than three decades, pushing to protect health privacy and abortion rights and playing a key role in the passage of President Barack Obama’s health care overhaul, died on Friday in Washington. She was 88 and in the midst of her 16th term in the House. She was handily re-elected every two years until 2014, when, in a year in which the Republicans increased their majority in the House, she squeaked through to victory by fewer than 1,000 votes against her Republican challenger, Mark Assini. In a rematch with him in 2016, however, voters, by a 12-point margin, sent Slaughter, the dean of New York’s congressional delegation, back to Capitol Hill.