(JTA) — Chelsea Clinton announced that she and her husband, Marc Mezvinsky, are expecting their second child. Clinton made the announcement Monday in a Twitter post that shows a photo of the couple’s 15-month-old daughter, Charlotte, reading a book titled Big Sisters are the Best. Clinton’s mother, Democratic presidential candidate and former Secretary of State Hillary Rodham Clinton, responded on Twitter moments later saying she and her husband, former President Bill Clinton, are “so excited to meet our second grandchild.” Mezvinsky, who is Jewish, is the banker son of two ex-Congress members. Clinton serves as the vice chairwoman of the Bill, Hillary & Chelsea Clinton Foundation. Clinton and Mezvinsky were married in late July 2010 under a traditional huppah, or wedding canopy, and recited the traditional sheva brachot, or seven wedding blessings. A rabbi and a Methodist minister officiated at the wedding. The couple signed a ketubah, or Jewish marriage contract.