Timeline of William and Kate's relationship

LONDON - Prince William's wife Kate has entered a London hospital to give birth to their second child, who would be fourth in line for the throne. Here are some highlights of their lives and of the royal pregnancy:

September 2001: Prince William and Kate Middleton meet at St. Andrews University in Scotland where both are studying art history.

Christmas 2003: The pair reportedly become a couple after sharing a house with two friends. In March they are pictured together on a skiing holiday in Switzerland.

Nov 16, 2010: William and Kate's engagement is announced. The prince proposed to Kate while on a private holiday to Kenya the previous month.

April 29, 2011: The pair wed in a lavish ceremony at London's Westminster Abbey. William is made the Duke of Cambridge by his grandmother, Queen Elizabeth II, and Kate becomes the Duchess of Cambridge.

Dec 3, 2012: The palace announces that Kate is pregnant and being treated in the hospital for acute morning sickness. She is discharged from the hospital after three nights, telling reporters she is feeling ``much better.'' The palace later announces that the baby is due in July.

Feb 5, 2013: The couple take a holiday on the Caribbean island of Mustique with Kate's parents.

_March 17, 2013: Kate tells a soldier at a St. Patrick's Day parade that they do not know the sex of the child, but says she would like a boy but William wants a girl.

June 4, 2013: William and Kate return to their wedding venue when they join the royal family for a service marking the 60th anniversary of the Queen's coronation at Westminster Abbey.

June 15, 2013: The Duchess makes her last scheduled public appearance before the birth at the Trooping the Color parade.

July 22, 2013: Kate gives birth to a baby boy, weighing 8 pounds, 6 ounces, with William by her side.

July 23, 2013: William and Kate take the baby home to Kensington Palace.

July 24, 2013: Royal officials say the new prince has been named George Alexander Louis. The announcement came after Queen Elizabeth II met her great-grandson. William and Kate then brought their child to her parents' home outside London.

April 7, 2014: William, Kate and George make their first official overseas trip as a family on an extended tour of New Zealand and Australia.

Sept 8, 2014: The palace announces that Kate is pregnant with their second child and is once again experiencing acute morning sickness that forces her to cancel a number of official commitments.

Oct 21, 2014: Kate resumes royal duties after her morning sickness eases. She and William welcome the president of Singapore to London at the start of a state visit. She carries out numerous official duties throughout her second pregnancy.

Mar 18, 2015: During a visit to a children's center, Kate tells a volunteer she is due mid to late April. "Not long to go now," she says.

May 2, 2015: Kate is admitted to London hospital for birth of her second baby.