Baltimore has become the first major city to prohibit restaurants from including sugary drinks on children's menus.

The measure, which went into effect on Wednesday, is intended to promote healthy habits in young children and their families by making the default kids' menu options water, milk and 100 percent fruit juices.

Parents will still be able to order sugary drinks, such as sodas, for their children.

Several smaller cities in California, as well as Lafayette, Colorado, have implemented similar ordinances, but Baltimore is the largest city in the country and first on the East Coast to do so.

While the country as a whole is struggling with childhood obesity, the problem in Baltimore is particularly pronounced: One in three high school children is obese, and one in four children drinks one or more sodas a day, according to Baltimore Health Commissioner Dr. Leana Wen.

"The science is clear that a major contributor to childhood obesity is sugary drinks, and taking out these empty calories is one of the single biggest lifestyle changes that parents and children can make," Wen told NBC News.

Sugar Free Kids Maryland, and healthy eating advocacy group, has been fighting for this type of legislation for years, according to Executive Director Shawn McIntosh.

“Baltimore city families eat out on average 2.4 to three times a week, which is pretty significant,” McIntosh said. “So this is a way of helping families have healthier beverage options for their children, so they start making healthier choices outside the home, and then inside the home.”

Public health experts said that while this is definitely progress, fruit juice as an alternative option is a point of concern.

“Some juices do contain more fiber and vitamins, but some juices, such as apple juice, in fact have been used as a sweetener, and it contains a lot of sugar, so it is still not recommended in large amounts for children,” said Dr. Claire Wang, an associate professor at Columbia University’s Mailman School of Public Health who specializes in policy that fights childhood obesity. “Personally, I think [the ordinance] is one step towards the right direction. The 100 percent fruit juice in modest doses is still superior to a soda.”

Professor Frank Hu, the chair of the Department of Nutrition at Harvard University’s T.H. Chan School of Public Health, said that he thinks “this kind of message can influence the behavior of parents and drinking habits of the entire family, so it’s something that can have a wide effect.”

He also cautioned, however, against fruit juice and other sugar-heavy alternatives, and noted that it will be important to do thorough evaluation of these cities in future years.

Kristen Hoffmaster, a Baltimore parent of three children, said that removing sugary drinks from children’s menus will ideally make groups of kids collectively decide to choose healthier options.

"I think it’s also a social thing for kids, it’s fun to drink soda, it’s cool to drink soda, it’s not as cool to drink water, milk isn’t as exciting,” she said. “Kind of vamping that up and making it cool to drink water again and cool to be healthy, that’s really important for kids."