She was born at six pounds, 11 ounces. My husband and I placed her down in the middle of our bed and stared in awe at that tiny body. For four-and-a-half years, that baby has grown and plumped, stretched and strengthened, and now it’s time to carry her behind an intimidating metal door and into school.

(Andrea Bruce/The Washington Post)

The first day of school gets lots of ink for all that it means to a child. There is anxiety and anticipation. There are new rules and friends and teachers. There are adorably awkward pictures.

For older children, the first day of middle school, high school, college all bring with them their own excitement and set of challenges.

Standing behind all these nervous kids are parents who are in transition, too. For us, the child’s new beginning brings a new phase of parenting, which means the end of another.

My colleagues Jennifer LaRue Huget and Joel Achenbach have written about the torture of saying goodbye to their college-bound children. I am here to say that the beginning of school is rough for parents, too.

Preparing for the first day has dredged up more guilt and regret than I ever knew I harbored. I find myself painfully wishing that this past summer I hadn’t worked so much, that I hadn’t become angry so often, that our days had been filled with fewer babysitters and more shared ice cream.

It feels like I’ve somehow missed my last chance at something. That door she walks through this morning is going to lead her to great new places, but it will close on me. Selfish? Check. Overwrought? Check. Real feelings? Check

“It’s a time of realization that your child is growing up. It’s the realization that you won’t be the only one molding them,” said Julie Bindeman, a Rockville psychologist I called to discuss how parents handle that first day of the school year.Why is it such an emotional experience?

Bindeman said school beginnings are ripe for identity shifting in both child and parent. At different grades — especially preschool, kindergarten, middle school and college — children break further away from their parents. Parents, in turn, have to absorb that they are needed less or in different ways.

“Identity is a fluid development across a life span,” Bindeman said. “Most of it is formed at a young age, but you see a major shift for people when they become parents. It changes the way we see ourselves, the way we see others.”

The transitions can be especially hard “if you get wrapped up in that ‘parent’ identity and your other identities get left behind.”

So maybe writing about parenting isn’t the healthiest option for handling these transitions? Probably not. Still, Bindeman said all kinds of parents feel wistful, including ones with more experience.

For all of us waving goodbye to our preschoolers and kindergartners, there will be parents who are dropping off their children at middle school “and realizing that childhood is more and more in the rearview mirror.” Or driving away from the college dorm, choking back tears. “That tends to be especially hard for fathers,” she said, because it’s such a stark change for home life.

Perhaps it helps to know that we are not alone. Bindeman said that parents everywhere are enduring these feelings and that “to work through anything, you have to acknowledge that it’s there and to acknowledge that it’s okay it’s there.”

Today, I’ll be acknowledging it through wet eyes. How about you?