It happened around 12:40 a.m. on the southbound freeway shoulder near the SR-22 connector in Santa Ana. The woman's husband was rushing her to the hospital when she just couldn't hold off any longer.
A veteran California Highway Patrol officer responded to the call. By the time he arrived, the bundle of joy had already been born and was sitting on mom's lap.
The officer called this a first for him in his 17 years on the job.
Both mom and baby were taken to the hospital and are said to be doing just fine.
City News Service contributed to this report.