"Physiological science" has found that driving "automatically affects the ovaries and pushes up the pelvis," Sheikh Saleh al-Luhaydan warned women in remarks to local news website Sabq.org.
"This is why we find that children born to most women who continuously drive suffer from clinical disorders of varying degrees," he said.
His comments prompted criticism on Twitter, which has become a rare platform for Saudis to voice their opinions in the absolute monarchy.
"What a mentality we have. People went to space and you still ban women from driving. Idiots," said one comment.
"When idiocy marries dogma in the chapel of medieval traditions, this is their prodigal child," wrote a female tweeter.
Luhaydan, a member of the senior Ulema (Muslim scholars) Commission and former head of the Supreme Judicial Council, said that "evidence from the Quran and Sunna (the teachings of the Prophet Mohammed) completely prohibit (women's driving) on moral and social background."
An online petition titled "Oct 26th, driving for women" amassed nearly 12,000 signatures, while access to it was blocked in the kingdom on Sunday.
Saudi Arabia is the only country where women are banned from driving.
Activists declared a day of defiance against the ban on June 17, 2011, but few women answered the call to drive. Some of those who did were stopped by police and forced to sign a pledge not to take to the wheel again.
Saudi Arabia imposes other restrictions on women, including a requirement to cover themselves from head to toe when in public.
The 2011 call, which spread through Facebook and Twitter, was the largest mass action since November 1990, when 47 Saudi women were arrested and severely punished after demonstrating in cars.