Groups including the American Restroom Association and the World Toilet Organization view quick access to clean public toilets as no laughing matter. People with medical problems, including bladder or bowel dysfunction, may not be able to wait. Long waits can exacerbate other issues, including urinary-tract infections.

For years, women have most dealt with the consequences, if not the indignity, of waiting in long lines.

New York City passed a law in 2005 requiring that all new or significantly renovated places of public assembly  concert halls, arenas, Broadway theaters, stadiums and the like  have two women’s toilet fixtures for every one devoted to men. About half of the states and many municipalities have similar laws, with varying ratios, designed to offset the extra time that women take in the restroom and slowly undo decades of male-dominated design and construction.

“Until relatively recently, most architects, contractors, engineers, building-code officials and clients were not concerned about this issue,” Dr. Anthony said. “These were very male-dominated professions, and still are. They rarely contacted women about their restroom needs.”

New York’s law came as the city was overhauling its plumbing and building codes, much of which dated to 1968. The city based its plumbing code on the 2003 version of the International Plumbing Code, which has specific requirements for toilet fixtures for various types of buildings and occupancies. Almost always, women are to be supplied with more.

But because most assembly halls in the city are decades old, they generally lack in women’s restrooms. New construction provides a rare chance to make right.

The new Yankee Stadium, with a capacity of 52,325, needed a minimum of 358 women’s toilets and 176 men’s fixtures, of which no more than half could be urinals, according to the city Department of Buildings.