US First Lady Michelle Obama greets children upon arrival at the Benito Juarez International Airport in Mexico City, on April 13, 2010. Obama is in Mexico in a three-day official visit. AFP PHOTO/Luis Acosta (Photo credit should read LUIS ACOSTA/AFP/Getty Images) No UK until 2 June 2011Mandatory Credit: Photo by REX/Shutterstock (1329339b)Michelle Obama poses in the Music Room of Buckingham Palace ahead of a State BanquetUS President Barack Obama State Visit to London, Britain - 24 May 2011Queen Elizabeth II poses with President of the United States Barack Obama his wife Michelle Obama as well as the Prince Philip, Duke of Edinburgh in the Music Room of Buckingham Palace ahead of a State Banquet on May 24, 2011 in London, England. The 44th President of the United States, Barack Obama, and his wife Michelle are in the UK for a two day State Visit at the invitation of HM Queen Elizabeth II. During the trip they will attend a state banquet at Buckingham Palace and the President will address both houses of parliament at Westminster Hall. WASHINGTON, DC - NOVEMBER 19: First lady Michelle Obama stands on stage during an awards ceremony for the President's Committee on the Arts and the Humanities in the East Room at the White House on November 19, 2012 in Washington, DC. The first lady talked about the importance of afterschool and out of school arts and humanities education and presented awards recognizing programs across the country that benefit underserved youth. (Photo by Mark Wilson/Getty Images) Mandatory Credit: Photo by REX/Shutterstock (2127683w)Michelle ObamaPresidential Inauguration, Washington DC, America - 21 Jan 2013 US First Lady Michelle Obama speaks at a screening of "The Powerbroker: Whitney Young's Fight for Civil Rights," at th Eisenhower Executive Office Building in Washington, DC, on August 27, 2013. The screening is a part of celebrations commemorating the 50th anniversary on the March on Washington, the civil rights watershed where Martin Luther King Jr famously declared: "I have a dream." The March on Washington is best remembered for King's stirring vision of a United States free of inequality and prejudice, telecast live to a nation undergoing a phenomenal decade of soul-searching, crisis and change. AFP Photo/Jewel Samad AFP Photo/Jewel Samad (Photo credit should read JEWEL SAMAD/AFP/Getty Images) WASHINGTON D.C. - SEPTEMBER 27: U.S. President Barack Obama and First Lady Michelle Obama arrive on stage for the Congressional Black Caucus Foundation Annual Phoenix Awards dinner, September 27, 2014 in Washington, DC. The CBC's annual conference brings together activists, politicians and business leaders to discuss public policy impacting Black communities in America and abroad. (Photo by Olivier Douliery-Pool/Getty Images) LONDON, ENGLAND - JUNE 16: US First Lady Michelle Obama holds flowers as she is received by young students holding the American flag in the courtyard before an event as part of the 'Let Girls Learn Initiative' at the Mulberry School for Girls on June 16, 2015 in London, England. The US First Lady is travelling with her daughters, Malia and Sasha and her mother, Mrs. Marian Robinson, to continue a global tour promoting her 'Let Girls Learn Initiative'. The event at the school was to discuss how the UK and USA are working together to expand girl's education around the world. (Photo by Jeff J Mitchell/Getty Images) Mandatory Credit: Photo by Masatoshi Okauchi/REX/Shutterstock (4546119k)Michelle ObamaMichelle Obama at Haneda International airport, Tokyo, Japan - 18 Mar 2015WEARING KENZO Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.Mandatory Credit: Photo by Frank Franklin II/AP/REX/Shutterstock (5900837c)Michelle Obama First lady Michelle Obama speaks as she hosts Broadway Shines A Light on Girls' Education, at the Bernard B. Jacobs Theatre in New YorkBroadway Shines A Light on Girls' Education, Bernard B. Jacobs Theatre, New York, USA - 19 Sep 2016 Mandatory Credit: Photo by REX/Shutterstock (6403098a)President Barack Obama and First Lady Michelle Obama wait at the North Portico of the White House in Washington, DC.Matteo Renzi visits Washington, USA - 18 Oct 2016US President Barack Obama (R) and First Lady Michelle Obama (L)walk out of the White House to greet Italian Prime Minister Matteo Renzi and Italian First Lady Agnese Landini during an official arrival ceremony on the South Lawn of the White House. President Barack Obama and First Lady Michelle Obama wait for Prime Minister of Italy Matteo Renzi and Agnese Landini to arrive at the North Portico of the White House in Washington, DC. WEARING CUSTOM ATELIER VERSACE US First Lady Michelle Obama attends the 102nd White House Correspondents' Association Dinner in Washington, DC, on April 30, 2016. / AFP / NICHOLAS KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)