In 2011, NFL cornerback Antonio Cromartie, father of 10, decided that his baby-making days were over and got a vasectomy. Of all the birth control options available to men, vasectomies are considered the most effective and permanent — it’s known as “male sterilization” for a reason — but the free agent’s penis doesn’t appear to care for those rules. On Thursday, he and his wife Terricka announced that they had recently welcomed a new baby into the world.

Baby Jhett Paxton, born on August 30, is actually the third baby Cromartie has fathered since his vasectomy, making her his 14th child, according to TMZ Sports. His continued ability to spread post-vasectomy seed hints at either of two issues: a poorly managed recovery period or a freak of biology.

Vasectomies are thought to be permanent because they block the only path connecting the testicles, where sperm are born, and the seminal vesicles, where sperm join other fluids to become semen. What male ejaculate consists of, after all, is only 1 percent sperm: The rest is seminal fluid, a mix of proteins, vitamins, and minerals that keep sperm alive during their journey.

A post-vasectomy dude’s ejaculate should comprise all that, minus the sperm. As the diagram below shows, there’s just no way for his sperm to get out if his vas deferens (hence the name vasectomy) is blocked — usually by cutting and tying it, clamping down on it with surgical clips, or cauterizing it with an electrical current. Sometimes, surgeons opt to block it with an injectable plug.

The areas circled in red mark the vasectomy zone.

But sperm-proofing a vas deferens isn’t instantaneous. After a vasectomy, sturdy sperm can stick around in the tubes adjacent to the cut for up to three months. Usually, doctors ask patients to come in and masturbate into a cup a couple of times after their surgery so they can count the sperm in their samples, and they recommend using an additional form of birth control until that count reaches zero.

In an interview with USA Today, urologist Dr. Jay Sandlow of the Medical College of Wisconsin said that, because we have no confirmation of whether Cromartie’s sperm count actually reached zero, it’s possible that the procedure was simply not done properly and that some sperm continued to leak out. This would explain how Terricka gave birth to twins in 2016, which meant that she would have had to conceive well after the three-month recovery period.

There is one other possibility, though it’s rare: That Cromartie’s vas deferens simply grew back. As an article on Planned Parenthood explains, “There’s a very slight chance that the cut ends of your vas deferens can grow back together after a vasectomy, which means you could cause a pregnancy.” There’s not much humans can do to prevent or predict this.

Nevertheless, vasectomies are the most effective method of birth control for guys, with a 1 in 1,000 chance of getting pregnant after the first year, and a 2-10 in 1,000 chance after five years, according to the American Pregnancy Association. Altogether, this adds up to a less than 1 percent chance of getting someone pregnant, which is much more than a guy could hope for when using condoms (17 percent, according to the National Center for Health Statistics) or by pulling out (18 percent).

Of course, for Cromartie, who coincidentally has just announced his USA Network reality show called The Cromarties that is all about his “blended” family — made up of his 14 kids from seven women — having such robust physiology obviously pays off. Terricka has confirmed, however, that child number 15 is not going to happen.

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