Navy Pier has boosted security after a pregnant female was hospitalized and five people were arrested during a wild Friday night fracas at the popular tourist destination.

“We had a significant number of unruly teens who came to the pier and unfortunately ruined it for some of the other people who were having a great time,” Navy Pier spokesman Nick Shields said Monday of the disturbance at 7:45 p.m. Friday.

Police and witnesses have said anywhere from 30 to 100 brawling youths stormed through the pier’s Winter WonderFest, which is billed as a family-friendly event.

With the new security measures in place, anyone under 18 needs to be accompanied by a parent or guardian, Shields said. Anyone 18 or older must show a photo ID when purchasing tickets to enter the 170,000-square-foot playground, which features rides, giant slides and an indoor skating rink.

Shields also said additional security guards will be working at the 14th annual event, which runs through Jan. 11. He declined to discuss specifics of the updated security plan.

This is not the first time mobs of teenagers have wreaked havoc in tourist-friendly areas of downtown. Beat cops have taken to call such events “wildings.”

And two other similar disturbances broke out over the weekend, though one was at a mall the southwest suburb of Chicago Ridge. There, a large group of young shoppers rampaged through the mall on Saturday night. One witness described it as a “riot.”

Then, early Sunday, a group of younger-looking people fought inside River North’s iconic Rock ‘n’ Roll McDonald’s, bashing themselves and restaurant décor with chairs.

The fight was captured on video and posted to YouTube, though police said no arrests had been made as of Monday night.