STAFF AT Merrimack Health’s Methuen campus – formerly Holy Family Hospital – delivered the facility’s last baby today after the hospital announced last week it would move the expected closure of its maternity unit up by more than a month. On April 1, the three-campus health system announced its plans to shutter the obstetric unit on August 1 and consolidate its maternity and neonatal services at Lawrence General Hospital, which is less than two miles away.