In his speech at a White House soiree in their honour, President Barack Obama poignantly spoke of their strength as parents.
The remarks were clearly a reference to David and Samantha's late son Ivan, who suffered from epilepsy and cerebral palsy and died in 2009.
Earlier in the day, the Prime Minister and his wife showed their commitment to helping others in his memory.
They visited National Children's Center, which provides services for children and adults with developmental disabilities.
Holding seven-month-old Abria Law, who was born three months premature, weighing just one pound six ounces, the British premier smiled tenderly.
Meanwhile, Samantha, in a dress from Victoria Beckham, gave the baby one of her fingers to hold and chatted to her mum LaJoy.