Akeela Ali, 25, was caught on camera engaging in sexual activity with her husband Fahad Bilal, 26, in Westfield Shopping Centre in Shepherd's Bush, west London.
The footage, which lasted 10 minutes, showed Ali "moving her head up and down" before going on to spit into a tissue and discarding it into a flower pot, a court was told.
During Bilal's interview, he described the encounter as "a human mistake" and said the couple had not "made a prior decision" to engage in oral sex.
Ms De Silva added: "It was not that busy at the time but he knew it was a public area."They thought about stopping when the children interrupted but continued."The couple, who represented themselves, were sentenced separately as they took turns to look after their children outside the courtroom.
Speaking from the dock, Ali said: "I'm just quite ashamed of what I did, I'm not happy with what happened.
Ali and Bilal have now been barred from London for eight weeks after pleading guilty to outraging public decency at Hammersmith magistrates' court - with the children in tow.
The couple said they had "thought about stopping" when their kids caught them but decided to carry on, late explaining: "It just happened."Pregnant Ali explained during her police interview that her hormones "were everywhere" and that she just "felt horny".
The family, from Newport, Wales, had travelled to the capital for the day on July 23.
Prosecutor Arlene De Silva said: "Mrs Ali sat beside her husband and lifted the jacket on his groin.
She then began moving her head up and down and was clearly engaging in oral sex."She placed her right hand under the jacket and appeared to be masturbating him.
This went on for around 10 minutes."They were interrupted several times by the children.