The couple with their son, Aaron.

WHEN Adam Gertsacov and Stephanie Schwab were married three years ago, she was a vice president at a New York social media agency and he ran a small start-up from their house in Yonkers. A very small startup: the Acme Miniature Flea Circus.

In the act, conceived as a playful homage to old-time show business, he leads two fleas calls Midge and Madge through chariot racing and tight-wire dancing, then shoots them out of a miniature cannon into a tiny Airstream trailer.

In recent years, though, both the fleas and Mr. Gertsacov, 46, who is a graduate of both the University of Pennsylvania and Ringling Brothers and Barnum & Bailey Clown College, have been performing less often. He is now the primary caretaker of a larger creature: the couple’s 2 ½-year-old son, Aaron.

“My work as a clown is about listening and improvising,” Mr. Gertsacov said. “That comes in handy when Aaron doesn’t want to do what I want to do.”

The son may fill his father’s big shoes one day; prodded by his dad, he even donned a ringmaster hat and performed somersaults for a guest. “I have some ideas about how to incorporate him into an act,” Mr. Gertsacov said.

“Whether or not his mom lets him,” added Ms. Schwab, 43.

Those doing the math may have gleaned that Aaron is only slightly younger than the marriage. At the couple’s wedding at the Roosevelt Ballroom in Yonkers, Ms. Schwab was five months’ pregnant. The couple had been involved for nearly four years when she found she was expecting. Days later, Mr. Gertsacov’s mother died of cancer, and they decided to marry. Their wedding had many clownish touches, like the rings being extracted from a Cracker Jack box.

After Aaron’s birth, Ms. Schwab took two months’ maternity leave, then returned to work. They hired a part-time sitter so that Mr. Gertsacov could concentrate on his job directing Bright Night Providence, a New Year’s Eve celebration in Providence, R.I., that he co-founded when he lived there. After the festival was over, he became the stay-at-home parent.

Ms. Schwab, with her breast pump and daily commute to Manhattan, often felt disconnected. “The first two years,” she said, “I made Adam and the sitter write down every poo, every feeding, every ounce of milk Aaron took, when he slept and when he woke up. I would get home and say: ‘What did he do today?’ What went on?’ ”

Eventually, she learned to trust her husband. “I couldn’t micromanage remotely,” she explained.

Focused on Aaron, Mr. Gertsacov stopped pursuing gigs for the flea circus and another act, “The Puppet Tragedy,” which includes a “Glass Menagerie” performed with real glass and “The Vegetable Macbeth,” at the end of which, Mr. Gertsacov said, “I juice the cast and drink it.”

He has no regrets about shifting from ringmaster to homemaker. “I was afraid I would resent being tied down and that I wouldn’t love my kid,” he said. “After he was born I realized my fears were completely unfounded. Now I have new fears, like the fact that when he turns 18 I’ll be 61.”

As new parents past 40, the couple nonetheless found child-rearing less stressful than the extensive renovation of their Victorian fixer-upper. “We renovated a house, got married and had a kid, one after another,” Mr. Gertsacov said. “Change is normal.”

When someone has a child later in life, Ms. Schwab added, “you are already who you are.”

“You’re not changing as people,” she continued. “We’re pretty settled in what we want out of our lives so we don’t fight much.”

Her marital résumé is longer than her husband’s; she had two short-lived marriages during her 20s. “I knew how not to be married,” she said. “I knew that I had to let go of a little bit.”

After Aaron turned 1, the couple decided he would be an only child. “I really thought we would have more,” Ms. Schwab said, “but once we had him we realized we were too old — staying up all night and breastfeeding around the clock. We were exhausted.”

Last May, they faced a new change. Ms. Schwab founded a digital media concern, Crackerjack Marketing, and now both husband and wife work from home.

“Whether or not Adam will admit it, he feels like I am more underfoot,” she said. “I’ll come down for lunch and ask what he’s done today. He’ll say, ‘Nothing.’ ”

Mr. Gertsacov, who fetches Aaron from school and makes dinner while Ms. Schwab works upstairs, admitted, “I might feel that she’s nagging me a little bit.”

Asked why they seldom argue, they credited technology and a smart suggestion. At their Aufruf, a Jewish ceremony before their wedding, couples in their temple offered advice. According to Ms. Schwab, “the most elderly couple in our synagogue stood up and said, ‘We have two pieces of advice for you — separate bathrooms and separate televisions.’ ” Mr. Gertsacov now watches “Justified” and “Archer” on the set downstairs while Ms. Schwab watches “Top Chef” in their bedroom.

When arguments do occur, they usually involve colliding agendas. As he is on his way to get Aaron, she will tell him what errands to run, and in what order. “Adam will put his palms up, say, ‘maybe,’ and walk out the door,” she said. “I’ll have no idea and no control over what they do.”

Mr. Gertsacov explained: “I don’t like to be told what to do. That’s part of having lived alone for a long time.”

Another recurring disagreement concerns Garrison Keillor. Mr. Gertsacov greatly admires him, but Ms. Schwab does not share that sentiment. Yet she bought them tickets to “A Prairie Home Companion” at Town Hall in Manhattan in the hope that a live show would convert her. In a later telephone interview she said, “The jury is still out.”

Now that Aaron is in preschool, Mr. Gertsacov is developing shows about Henry Hudson and P. T. Barnum, and is to perform the flea circus in July at the Hudson River Museum in Yonkers. His ringmaster act intact, he fires off three flea jokes with very little prompting: “That’s the show people are itching to see. That’s how I make my scratch. I don’t perform for flea.”

While Ms. Schwab took Aaron upstairs for a nap, Mr. Gertsacov set up his stage and excitedly ran through the act — without his current Midge and Madge. He said they were sequestered at a friend’s studio to train for the coming performance. “I don’t show them to people in general,” he said earnestly.

Asked how he responds to those who question the very existence of Midge and Madge, he said, “In some ways I welcome that.” He added: “The show is 30 minutes long, 40 minutes with laughter. It’s about the audience and me sharing a moment together.”

As he paged through a book of flea trivia, Ms. Schwab came downstairs and watched happily. “I’m less jealous of the fleas,” she said, “now that we have Aaron.”