After some panicked Googling, I thought I had found the culprit: A few weeks earlier, I’d come down with strep, and the family doctor had prescribed an antibiotic. I had taken the antibiotic with no thought whatsoever about birth control.
Aha! That explained it, I thought. And the doctor later confirmed my suspicion: The antibiotic, she said, might have lowered the efficacy of the pill. (This turns out not to be the likely explanation — more on that below.) A week later, I had a miscarriage.
We changed insurance plans, and soon I found a highly recommended OB/GYN and asked about getting an intrauterine device. Based on some factors related to the ultrasound the OB required before ordering an IUD, she talked me out of it. Furthermore, an IUD would have cost me about $600, even with our excellent insurance plan.
Figuring that my previous unplanned pregnancy was just a fluke, I went back on the same pill. It cost me only $5 per month, I was a reliable pill taker, and switching to a different form of birth control seemed like a hassle. A few months later, I discovered I was pregnant again.
My third child is now 9 months old. I wouldn’t change anything and can’t imagine my life or our family without her.
Still, most women take the pill because they expect it to work. There’s something unsettling about using the most common form of birth control and then finding out that you have so little “control.”
The responses I got from local obstetricians ranged from: “Did you take the pill at about the same time every day?” (that, it turns out, shouldn’t have mattered) to wonky and wrong explanations about differences in formulation between generic and brand-name pills.
Getting to the bottom of why the pill failed me — not once, but twice — has felt about as scientific as voodoo. As I soon found out, there are more questions than answers about why the pill usually works but sometimes doesn’t.
The failure rate
Researchers are struggling to understand how a person’s individual traits — genetics, metabolism, obesity, diet and other factors — might make certain drugs, including the pill, work reliably for some people but not for all.
“I can’t even give you a scientific answer, even if you missed a pill,” says Colleen Krajewski, an OB/GYN who is affiliated with Johns Hopkins for contraception-related research projects, when asked to explain what might have caused my pill failures.
“My guess is it was sort of the perfect storm of little things,” she says.
The first thing that obstetricians like to remind you is that no method of birth control is 100 percent effective.
Researchers break statistics on efficacy of contraceptives into two categories: perfect use and typical use.
With perfect use — a term that basically applies to women in research studies who are being paid to take the pill in a regimented fashion — the pill is 99 percent effective. But with typical use, meaning women in the general population who use the pill imperfectly, the effective rate drops to 91 percent.