This fall, about three million children younger than 14 are playing organized tackle football in the United States. Is that a good thing?

For many parents and coaches, that means three million children are getting some pretty serious exercise, hanging out with old friends and making new ones, and unplugging from technology, for a few hours at least.

I see those positives. Yet if it were my call, those millions would be playing touch football instead. Many would be learning the fundamentals of tackling and other football skills. But they would not be playing tackle football until they turned 14.

The reason is simple. Tackle football is too dangerous for youngsters. Exposure to head trauma is too risky. What we know about football and the vulnerabilities of children’s brains leads me to this conclusion. More worrisome is what we don’t know. How will the hits absorbed by a 9-year-old today be felt at 30, or 50?

I’ve been treating young athletes for concussions and other head trauma for four decades. In an average year, I’ll meet with patients to discuss their concussion symptoms 1,500 times or more. I’ve treated children for concussions in any sport you can name, and a few you wouldn’t think of. I’ve seen pole-vaulters, BMX riders and tennis players. Not that long ago, I treated a young man injured playing Ultimate Frisbee.

I’m not in favor of abolishing any sport for children, football included. Sports have too much to offer young people. There is nothing like being part of a Little League team or competing as a swimmer, tennis player or golfer to promote perseverance, sportsmanship, fair play, to keep fighting until the last point in the match or the last out. These are traits that carry us through life’s challenges.

In light of what we now know about concussions and the brains of children, though, many sports should be fine-tuned. But many parents and coaches are satisfied with the rules as they are. They like seeing youngsters in helmets and pads, and watching them slide headfirst into second base. The closer the peewee games resemble those of the professionals, the happier we are. It’s natural for a parent or a coach. Even a neurosurgeon.

But children are not adults. Their bodies are still maturing. Their vulnerabilities to head trauma are far greater.

A child’s brain and head are disproportionately large for the rest of the body, especially through the first five to eight years of life. And a child’s weak neck cannot brace for a hit the way an adult’s can. (Think of a bobblehead doll.) A child’s cranium at 4 is about 90 percent the size an adult’s. That’s important to a discussion of concussions and concussion risk.

We cannot eliminate head trauma from youth sports. What we can change is our mind-set so protecting the head and the brain is always a top consideration.

The guiding principle should be that no head trauma is good head trauma. Let’s re-examine youth sports and take steps to keep young athletes safe. I would like to see these changes written into the rules across the country.

SOCCER Many parents and coaches are surprised to learn that soccer is not among the safer sports for head trauma. It is actually one of the riskiest. In 2010, more high school soccer players sustained concussions than did athletes in basketball, baseball, wrestling and softball combined, according to the Center for Injury Research and Policy in Columbus, Ohio.

Most of that risk comes from one play: heading the ball. When two or more leap to direct the ball with their heads, a number of collisions can occur with heads, shoulders and elbows. From a neurological standpoint, nearly all are bad. About 90 percent of the patients I see with soccer head trauma and concussion are related to heading accidents.

It’s an easy call for me: take heading out of soccer until the players are 14.

ICE HOCKEY The progressive leadership of USA Hockey and Hockey Canada have done most of the heavy lifting in this sport. Hockey Canada outlawed checking to the head throughout amateur hockey. In 2011, USA Hockey approved a ban on body checking before the age of 13. I would extend the ban on body checking to 14. (The previous rule permitted body checking for players as young as 11.)

BASEBALL AND SOFTBALL Batting helmets are mandatory at every level of baseball, yet it’s surprising how little we do to ensure that they stay on. Some youth leagues around the country have mandated chin straps for years. All youth and high school leagues should require them.

In addition, headfirst slides should be eliminated. When a child’s head plows into an ankle or a shin, the leg always wins. Worse are home-plate collisions in which the head of the base runner can crash into the catcher’s hard shinguards.

FIELD HOCKEY AND GIRLS’ LACROSSE

I have heard that girls would be emboldened to play more aggressively if helmets were required in these sports, and that the net effect would be more injuries, not fewer. I say hold officials accountable for enforcing the rules, and that will not happen.

In lacrosse, some officials now favor something like a bike helmet to protect the top of the head. That is not good enough. When helmets that cover the entire head are required, fewer young women will sustain concussions.

Field hockey rules state that players should not raise their sticks above the knee. But that rule is broken in every game, often resulting in concussions, eye injuries, cuts, broken noses and more. Helmets are needed, although they do not have to be as robust as football helmets.

]I would expect resistance to these recommendations from parents of the 16,000 players in Pop Warner football’s tackle division for 5- to 7-year-olds, for example. But let’s begin the debate.