The singer, 32, shot to fame in 2011 when she appeared on The X-Factor and was placed into girl group Little Mix alongside Jesy Nelson, Perrie Edwards and Leigh-Anne Pinnock.
The Little Mix star, 34, has been in hospital since late March after being diagnosed with twin-to-twin transfusion syndrome (TTTS) - a rare condition that can put one or both babies at risk.
And among those on the starting line were Joel Dommett, Kelly Brook, Harry Judd and Adele Roberts, who took to their social medias ahead of the race to voice both their excitement and nerves.
The Little Mix star, 34, revealed earlier this week that she's been diagnosed with pre-twin-to-twin transfusion syndrome, meaning one or both babies could be at risk of death.
When popstar Jesy Nelson announced her first pregnancy on Sunday, fans eagerly waited for messages of support from her three childhood best friends and former Little Mix bandmates.