I'm one of the unlucky 0.1% of people who get pregnant with a copper IUD. I had an abortion after it failed.

• My gynecologist recommended the copper IUD and told me it was 99.9% effective.
• I was stuck on that 0.1% statistic, and it turned out I was part of that small group.

I distinctly remember sitting on the exam table at the consultation appointment for my IUD and getting hung up on the 0.1%. My gynecologist had recommended the copper IUD as a safe, reliable birth-control option that doesn't use hormones, which was important to me. It was 99.9% effective, both she and the pamphlet she handed me said. I've never been good at math, but that remaining 0.1% stuck out to me.

"I'm just trying to understand this," I told her. "But doesn't that mean if I have sex 1,000 times, I'm guaranteed to get pregnant once?"

My gynecologist seemed annoyed at my logic. "No," she said. "It's more like out of 1,000 people, the IUD won't work for one."

I pictured a thousand people sitting in an auditorium, a name being called, and then one unlucky person spontaneously combusting. It wasn't a room I wanted to be in, but what were my choices?

"Erin," my gynecologist said. "This is the closest I can make you to sterile."

So I got the IUD.

My periods were heavy

The insertion went better than expected. A chipper nurse told me after the doctor had placed the T-shaped metal device in my uterus that I was the only patient who hadn't screamed. I felt spared. Lucky.

But 28 days later, my period started and my luck ran out.

The IUD made my flow so heavy it was almost comical; like a Quentin Tarantino movie. I would get one awful cramp at the onset of my cycle, bad enough that I'd double over, and then, the flood. I bled so much that I couldn't sleep through the night without drenching the sheets and the mattress. At work, I bled through my jeans and onto my office chair. I had to order a special menstrual cup and wear backup period-absorbent panties, and still, I'd run to the bathroom to stuff wads of toilet paper in my underwear. Leaving the house felt unnerving during those days. It was easier to just stay home.

Still, I considered this a fair trade-off. Yes, seven days of every month I bled so much I could barely live my life, but at least I didn't have to worry about getting pregnant.

And then I got pregnant.

My IUD failed

One month, three years after my IUD insertion, the biblical flood became more of a trickle. Stupidly, I rejoiced. My gynecologist told me my body might eventually adjust to the IUD, and I figured that's what was happening. Finally, relief.

That light bleeding turned out to be implantation bleeding, not a period. And by the time I realized it seven days later, I was 5-½-weeks pregnant.

I had an abortion. It wasn't a difficult decision for me. I had made the choice not to have a child when I got the IUD, and I followed through with it. The experience was unremarkable: I took some pills and an hour later I started bleeding. The procedure was less involved than getting a cavity filled.

No birth control option is 100% effective. You can make responsible choices and still get burned. I'm eternally grateful that when my IUD failed, I had access to a safe abortion. After all, someone has to be the unlucky 0.1%.