"Click, clack," I read, then paused. "Moo," Simon shouted as he cuddled in my lap in a chair at Starbucks.
A man walked up and smiled. "Your grandson is so adorable," he said.

I resisted the urge to glower. This man after all was paying Simon a compliment. I smiled back, then corrected the error as my 3-year-old son sucked his thumb and held onto my ear. "He's not my grandson. I'm his mother."

I used to lead a charmed life when it came to age stereotyping. People guessed my age at five to 10 years younger than reality. My dark blond hair hides most of the gray strands. A fan of tennis, biking, and most sweat-inducing sports, I do not struggle much with weight. But add a child to the mix, and looking like the new 30-something when you are 40-something is useless.

You Know What Assuming Makes

Strangers, whether it's that man I encountered at the Starbucks in my Boston suburb or that woman manning the cheese shop counter in rural Vermont last summer, all too often presume I'm Simon's grandmother. To them, it's the scenario that makes sense. Otherwise, I would be a very old Mom of a very young child. Gee, I am. I turned 46 in September, and Simon, my only child, turned 3 in January. I did not meet my husband till I was 40, and he, 43.

On the national scene, Jewishly, my husband and I are part of a growing demographic. Jews, according to several studies, marry later than other Americans and have babies later. The most recent National Jewish Population Study estimated that more than half of Jewish women age 34 and under had not yet given birth to a child. Translation: Many of us are having children at age 35 and up.

I know, even as more women join the mothering ranks in their 30s, I fall at the high end of the mother age scale. Fine. But please do not call me Grandma. I don't feel like an old Mom. Sure, after a few sets of tennis or of knee bends to pick up my toddler, my body aches more than it did in my 20s. But I'm also more comfortable with myself than I was in previous decades. I worked full-time for nearly 25 years before I had a child. After a year off to stay home with my child, I realized that what I wanted was a piece of both the work and stay-at-home mom worlds on my own terms. 

Now, I work two days a week when Simon is in day-care. Most of the time, I could not be happier. I work, and then the rest of the time I experience the most precious thing in the world--Mommy-and-me time.

The Balancing Act

At 40-something, I have a better idea than I did at 30-something about how to create a work-life balance. I do not have it all figured out. Yet, perhaps more easily than younger mothers, I can savor the day-to-day moments with my child without worrying so much about what comes next. If there's a downside, it's that I cannot relate to a lot of the conversations of the 20- and 30-something mothers, many of whom are still trying to figure out what they want to do with the rest of their lives.

Sometimes I connect better to grandparents of my son's peers. My son attends a weekly preschool class about Judaism at our temple. During that hour, the mothers and caretakers often chat. I often talk the most to the sole grandmother. We chat about current events, careers, and Judaism. And we talk about the joy of having toddlers in our lives. It sometimes feels like I have more in common with her than with the younger mothers. But still—don't call me Grandma!

Many studies attribute the rising age of new mothers to women's decisions to pursue careers first. But that wasn't the case for me. I wanted to have a family for as long as I can remember. My middle brother died at age 23 in a car accident; I was 21. Maybe tragedy made it harder for me to find love in my 20s and 30s. Why I did not get married or become a mother until my 40s matters little now. I could not be happier. My son knows my name. It's Mommy.

If you're also searching for a work-life balance, read how one woman uses the principles of Shabbat to find her way. 

Linda K. Wertheimer

Linda K. Wertheimer, a veteran journalist from Lexington, Mass., is writing a memoir about how the loss of her brother led her deeper into Judaism. She writes about faith and family on her blog at www.jewishmuse.com . Find Linda on twitter as @lindakwert.