In certain circles in New York, it is difficult to believe that the birth rate is at an all-time low. When it comes to having children in the city, three is the new two, and in the lush, leafy ‘burbs, four is the new three.

Twenty years ago, families of five, six, and seven were viewed as birth control mishaps. Not so today. “Our friends are all having four or five children,” a mother of three told me. “I almost feel like we have a small family.”

But parents of multiple children do worry about those darn birth control mishaps. A “happy accident” that brings the total number of children from two to three seems, well, happy. But what if the accident brings you from three to four, or four to five? Is the accident still so happy?

“We knew we were done having kids,” a father of four young children said. “So I had a vasectomy. The other day at some benefit I saw this really old guy with this gorgeous young blonde, his second wife. They had just had a baby. As far as I can tell, after the vasectomy, the only drawback is in that situation.”

Really? Somehow the thought of a vasectomy seems pretty drastic. But when I researched the subject, it turns out that my friend — well-educated and affluent, married with children, and almost middle-aged —fits the profile of those who have most of the 600,000 vasectomies each year in this country. According to the Guttmacher Institute, a nonprofit organization focused on sexual and reproductive health research, one out of every six men over the age of 35 has had a vasectomy, and the likelihood increases along with education and income.

I know many women who have opted for a tubal ligation, which is just a bit more common than a vasectomy. “A vasectomy these days is almost always reversible,” the father of four told me. “Having your tubes tied isn’t.” Having a vasectomy has become a quick in-office procedure — no scalpels — that is often covered by insurance.

“I started to do a Sudoku board in the waiting room, and I had just filled in a few numbers when they called me and said he was ready to go home,” a mother of three told me. “It was no big deal.”

“Easy for her to say,” her husband said. “It was uncomfortable. But we really didn’t want to have to worry about getting pregnant.”

“My wife didn’t like how she felt on birth control pills, and if for some reason we change our minds, especially in the next five years, it really is reversible,” he added.

Some parents really do worry over the thought of an accidental pregnancy, and for good reason. According to a 2005 study conducted by the Center for Disease Control, roughly 49% of all pregnancies and 30% of live births are unintended at the time of pregnancy.

But some men can barely even stand to hear the word “vasectomy,” let alone go ahead with the procedure. “No way,” said a father of four. “I don’t care what any doctor says, it just might make things different. I feel like it would take away my masculinity. It wasn’t meant to be like that.”

Many men view a vasectomy as a monumental sacrifice, but more men, according to a urologist in private practice in New York, are going ahead with the big snip.

“I’d say there’s been maybe a 10% increase in the number of men seeking vasectomies in the past few years,” he said in an email interview. “I do feel they are becoming more popular, especially in certain social circles in the city. Word has begun to be spread that it’s just not the biggest procedure. And by and large the men are married with several kids.”

Though the process has been simplified, men who have taken the plunge wouldn’t exactly say the aftermath was a ball. “The procedure was nothing compared to what happened afterward,” the father of four said. “I had the vasectomy done on a Friday and my kids were around that weekend, when I needed to be icing my, well, you know. We had to tell them something, so we told them that ‘Daddy has a boo-boo on his penis.’ My 5-year-old thought it was so funny that she told everyone in her class. Apparently the story was a big hit with the 5-year-old set.”

sarasberman@aol.com