The robbery was reported at about 12:25 a.m. at a home in the 4700 block of Antelope Circle, according to police.
The man and woman, who is two months pregnant, had arrived at the home along with three small children to gather belongings before moving to another city, police said.
The female victim went inside the home, and while the man waited in his car with the children he was approached by four suspects, one of whom had a handgun.
The suspect opened the driver's side door and pointed the gun at the victim while the other suspects ransacked the car and took personal belongings from the victim, according to police.
The suspects then forced the man out of his car and one stayed with him while the other three suspects entered the house, police said.
The pregnant woman was confronted in a hallway and ordered to the ground at gunpoint. While two of the suspects searched through the house, a third suspect searched through the female victim's pockets and kicked her twice, according to police.
The woman was not injured and declined medical aid or an ambulance after the robbery, police said.
The suspects were all about 18-20 years old, were wearing dark clothing and were last seen fleeing from the residence in a white or silver-colored sports car, police said.
Detectives from the Fairfield Police Department are investigating the robbery. Anyone with information about the crime is asked to call Fairfield police at (707) 428-7300 or Solano Crime Stoppers at (707) 644-7867 for a cash reward of up to $1,000 for information leading to an arrest.