On a warm Saturday morning in March, while the 20-something influencers and young finance bros of Williamsburg were still asleep, a group of more than 30 men gathered in McCarren Park.

Some were coming from as far as the Catskills and others from a few steps away. Greetings transitioned to talk of sleep training and stroller envy, and the bonding happened quickly. After all, they all had one major thing in common: babies. “How old is yours?” they asked one another as the group grew.

Benjamin Velez, 32, jogged up to the crowd with his 1-year-old daughter, Wynter, fresh from working an overnight shift as a switchboard operator and receptionist. One of the other men commented on the Monster energy drink in his stroller, and Mr. Velez pointed out that it also contained coffee.

Victor Ayala, 36, a quality control inspector, and his 2-year-old, Cassius, pulled up to the park in an Uber from Cobble Hill. The pair was praised for their style: Mr. Ayala was wearing a jersey, a white canvas jacket with black stripes, yellow sneakers and a Brooklyn Stroll Club hat. Cassius was kicking back in a Bape x Airbuggy stroller that his dad’s friend had shipped from Japan.