They can't ALL be lying...
July 30, 2007 1:04 PM   Subscribe

Three women I know, two of whom are pregnant and one of whom who had a baby three months ago, SWEAR that they were on the pill and taking it as instructed (same time every day, no missed pills) when they got pregnant.

I know one of these women very well (we work together) and she is so exacting and methodical in everything she does that I can't imagine her being five minutes late taking her pill, much less missing one entirely (and according to the birth control instructional insert, you don't even need back-up protection when you miss one pill). Other women I've known in the past have claimed that they got pregnant on the pill, and I assumed they were really bad at remembering to take it, or just trying to abdicate responsibility for the pregnancies. The three women mentioned above just don't seem like the types for that. Are all (or most) of these women lying, or is it that easy to get knocked up when you're doing everything right with the pill? I'm not asking because I want to call anyone out, I am just genuinely curious, and a teeny bit worried as I use the pill and I definitely don't want to get pregnant right now. I take it every night when I go to bed, between 10:30 and 12:00, and I haven't missed one by more than an hour in a year.

Anecdotal and scientific evidence are both welcome!
posted by Wroksie to Health & Fitness (39 answers total) 7 users marked this as a favorite
Perhaps your friends were taking antibiotics, St. John's wort, or suffering from vomiting or some other health condition. All those situations could reduce the effectiveness.
posted by acoutu at 1:08 PM on July 30, 2007

One woman I know got pregnant on the pill when she was taking antibiotics (don't remember which kind). Although she was taking the pill properly, the medication rendered the pill ineffective.

Another woman I know got a stomach bug and vomited soon after taking one of her pills. It hadn't been absorbed by her body yet, so it didn't work and she got pregnant.

posted by hurdy gurdy girl at 1:12 PM on July 30, 2007

I should have previewed...

Or, what acoutu said!
posted by hurdy gurdy girl at 1:14 PM on July 30, 2007

I've always heard that antibiotics or other medications are the biggest reason for birth control failure.
posted by Octoparrot at 1:15 PM on July 30, 2007

I read a thing in an issue of Cosmo about how it's important to take the pills at the same time every day. It said depending on the pill, even being off an hour can make it less effective.
posted by Becko at 1:18 PM on July 30, 2007

And I, and several women I know, have often missed one or two pills and just carried on, and not gotten pregnant (just as a counterpoint).

Yeah, I seem to remember reading that medication interactions/vomiting etc. were the main reasons that OCPs fail.
posted by gaspode at 1:19 PM on July 30, 2007 [1 favorite]

Well, according to the FDA, the "typical use rate of pregnancy" for both combined and progestin-only pills is 5% over one year. That means that in any given year, 1 in 20 women using birth control pills will become pregnant. So, why doubt any woman who says it happened to her?
posted by not that girl at 1:26 PM on July 30, 2007

My wife and I recently sold our toddler's co-sleeper crib to someone on Ebay who just had twins. I met with the parents of the new mom to deliver the crib. They said their daughter already had a toddler, and was on birth control pills when she got pregnant with her twins. It was a complete surprise to the new mom, and was told by her doctor that it was an extremely rare occurrence.
posted by jaimev at 1:26 PM on July 30, 2007

It happens. A friend in college was on the pill while not on any other drugs and still got pregnant. The pill certainly helps, but it's not foolproof.
posted by jmd82 at 1:31 PM on July 30, 2007

Your body weight may affect the efficacy of your pills, along with the above mentioned antibiotics and vomiting.
posted by peep at 1:32 PM on July 30, 2007

The pill is only 92-99.7% effective.
posted by damn dirty ape at 1:33 PM on July 30, 2007

Ack, an accidently early post, sorry. That 5% number is for "typical use," which means some pills missed or taken late, etc. The rate for women who manage to be perfect with it is much much lower but still not zero. It doesn't say how many women fall into each category!

I wonder to what extent women are able to reliably report their pill-taking? That is, how many women who think they are "doing everything right" are nonetheless varying the time they take it, or otherwise not quite getting it perfect.

I met a woman a few months ago who got pregnant four times in five years on four different birth control methods, each method with a lower failure rate. Every method (even sterilization, if you look at the FDA chart again) fails for somebody, sometime.

She liked her four kids, but she did seem a bit tired.
posted by not that girl at 1:33 PM on July 30, 2007 [1 favorite]

Here's a better link about body weight & the pill.
posted by peep at 1:36 PM on July 30, 2007

Scientific: The pill, like any other form of birth control, is not 100% effective. Even with perfect use, 1-2 women out of 100 will get pregnant over a year of use. (FDA)

Anecdotal: My best friend got pregnant about three months ago while on the pill, even though she did not miss a dose and was very careful about taking it on time.
posted by pitseleh at 1:39 PM on July 30, 2007

Antibiotics and other prescription drugs can mess with the efficacy of the Pill. So can tummy upsets and the common cold. And sometimes, you get pregnant anyway, even with perfect health and compliance. There is no 'perfect' contraceptive. Some are better than others, but the only really, truly, 100% effective contraceptive is abstinence. :)
posted by jlkr at 1:48 PM on July 30, 2007

And I, and several women I know, have often missed one or two pills and just carried on, and not gotten pregnant (just as a counterpoint).

That is not a counterpoint. It is perfectly possible to have sex and not get pregnant despite not taking birth control. It is just not at all reliable. Some couples try for months or even years to get pregnant before conceiving, so the likelihood of getting pregnant after missing one or two pills is still fairly low: it is just that it is higher than it was.

To the poster, you could consider keeping track of your cycle and doubling methods when you're ovulating or something like that, if you're really worried. No birth control method is 100%, though I think condoms are the most effective.

posted by mdn at 1:54 PM on July 30, 2007

"the only really, truly, 100% effective contraceptive is abstinence"

That's not true, actually. Castration, for instance, is a perfect contraceptive, and it still allows for normal sexual function. That said, very few methods are perfectly effective. For instance, my father, an emergency room doctor, once had the dubious privilege of informing a woman who had had a tubal ligation that she was pregnant.

More on topic, as others have pointed out, yes one can become pregnant while on birth control. If you're worried, you can use an additional unrelated method such as a copper ion IUD or a condom, or even all three together. Because they function in different ways, the probabilities multiply, leading to a vanishingly small chance of becoming pregnant. A back-of-the-envelope calculation suggests that a combination of the pill and a condom results in a .003% failure rate, which should be pretty acceptable for most people.

"though I think condoms are the most effective"

Not true. The failure rate for condoms, even with perfect use, is considerably worse than several other forms of birth control. The typical use failure rate is pretty bad, at 15%. The condom's real value over other methods is that it is largely side-effect free and prevents STDs. See this comparison of birth control methods for reference.
posted by jedicus at 2:09 PM on July 30, 2007

Castration, for instance, is a perfect contraceptive, and it still allows for normal sexual function.

I believe you meant to say "vasectomy". Castration does not allow normal sexual function. (Absent hormone replacement therapy, a castrated man loses interest in sex within a few months.)

A vasectomy leaves the testicles in place and doesn't interfere with the man's hormone balance.
posted by Steven C. Den Beste at 2:15 PM on July 30, 2007

No birth control method is 100%, though I think condoms are the most effective.

The FDA would disagree with you on that one. Most hormonal contraceptives, including most types of the Pill, Depo-Provera, and IUDs (which admittedly are not strictly hormonal) are all more effective at preventing pregnancy than condoms. And sterilization definitely is.
posted by Kadin2048 at 2:38 PM on July 30, 2007

Response by poster: Oh, man, this was just a simple question - can we leave rape out of this, and, pre-emptively, abortion as well?

I knew about the antibiotics thing - I think I remember reading somewhere that it might be an overstated risk, or maybe I made that up. Either way I'll still definitely abstain/use a condom if I need to take them, or if I get a stomach bug. And I should probably lose some weight, as well.
posted by Wroksie at 2:42 PM on July 30, 2007

I believe you meant to say "vasectomy". Castration does not allow normal sexual function. (Absent hormone replacement therapy, a castrated man loses interest in sex within a few months.)

Sorry for the derail, but I did mean castration as opposed to vasectomy. A vasectomy is not a perfect means of birth control. Castration does allow for normal sexual function in the sense that the plumbing still works. Ejaculate, for instance, is mostly a product of the prostate and other glands, not the testicles. And, as you point out, even interest in sex can be maintained with hormone therapy.

It is a pedantic point, perhaps, but I don't like the religious connotation that so often accompanies "abstinence is the only perfect form of birth control" as though god had made it thus and no human ingenuity could e'er thwart it.
posted by jedicus at 2:45 PM on July 30, 2007 [2 favorites]

When I've had an episode of vomiting after taking my pill, I've taken another pill of the same dose after I'm sure I can keep it down.

I asked my OB/GYN about the "take it within an hour of the same time every day" thing and he said that it wasn't quite that precise, but a two-hour window is a good reminder for a lot of people. In other words, If a typical week is 11:00 pm, 11:15 pm, 10:45 pm, 2:00 a.m., and 11:00 pm, you're probably ok.
posted by 100watts at 2:50 PM on July 30, 2007

I think that the real issue may be the newer, lower-dosage birth control pills that give you thinner margin of error for things like timeliness and weight. I have also heard that the antibiotics risk is overstated.
posted by footnote at 2:51 PM on July 30, 2007

Are all (or most) of these women lying, or is it that easy to get knocked up when you're doing everything right with the pill?

You're forgetting a third option:

It's very unlikely that any given person would know three women who got pregnant despite conscientiously taking the pill. However, there are a very large number of people in the UK, so extraordinarily unlikely events can be quite common.

That is, you're just unusual in having three friends who've gotten pregnant whilst on the pill.
posted by ROU_Xenophobe at 3:06 PM on July 30, 2007

You may also have friends who were taking the pill, but "forgot" on purpose. I am not accusing anyone here, so please don't jump on me, but this happens a lot more than women let on.

I was advised, when I wanted children, to pretend to "forget", since my husband wasn't ready. Obviously, I did NOT take the advice, and we had our children when we were both ready!
posted by misha at 4:18 PM on July 30, 2007

On Vasectomies: I am a post vasectomy baby. So hush about those being 100%. They have about a 0.015% failure rate (thank goodness for that, at least in my case). The hormonal IUD also has a 0.015% failure rate.

My theory, as a somewhat educated medical worker, is that the pill doses keep on getting smaller and smaller to avoid nasty side effects. This means, for any number of reasons, you could find them ineffective for a long enough period of time to get knocked up. Anything that screws with your digestive system, for instance, could easily cause such a failure, especially if you're overweight, or have some other factor influencing your drug absorption. And for some people, pills just plain don't work in their bodies.
posted by nursegracer at 4:33 PM on July 30, 2007

I know 4 people who've gotten pregnant while on the pill in the last year.
posted by fshgrl at 4:44 PM on July 30, 2007

Also, I know a family of 4 sisters all of whom have gotten pregnant multiple times while on birth control. And NOT accidentally-on-purpose. Some people are just more fertile or something.
posted by fshgrl at 4:45 PM on July 30, 2007

The dose of estrogens has been going down in oral contraceptive pills, because the medical complications of OCPs can be rather bad. The increased risk of blood clots (stroke, pulmonary embolus, Budd-Chiari syndrome etc.) and hepatic adenomas (a benign liver tumor) are all a little daunting.

When I think about it, I wonder why IUD's aren't more popular, since they're at least as effective and a lot less hassle. But I already know it's because of the old scares in the U.S.
posted by desiderandus at 4:52 PM on July 30, 2007

The hormonal IUD is brilliant.
posted by jb at 5:30 PM on July 30, 2007

I think some people prefer hormonal BC to IUDs because it controls your period - a lot of female doctors I've spoken to aren't even having periods anymore. Personally, I'm a big fan of the NuvaRing, fewer concerns about upset stomachs and such. And yeah - if you're at a place in your life where pregancy would be a big problem, why not use multiple forms of birth control?
posted by you're a kitty! at 6:13 PM on July 30, 2007

It really does amaze me how many women don't know that antibiotics decrease the effectiveness of birth control. It does! Spread the word because I think it's one of the biggest reasons for BC failure.
posted by misanthropicsarah at 7:21 PM on July 30, 2007

My firstborn was conceived while I was on the pill. I had begun taking the prescription just 2-3 months earlier.
posted by momzilla at 7:49 PM on July 30, 2007

The hormonal IUD also has a 0.015% failure rate.

And I know two people who have become pregnant while using them. This doesn't mean the stated failure rate is wrong, just that it's not zero percent and random things tend to clump. I also don't know anyone who has gotten pregnant while using condoms even though it's more likely, which just reflects the randomness of who I know rather than differences in contraception methods.

The thing is, a lot of these failure rates are for 'typical use', e.g. the 15% rate for condoms. This assumes that they aren't always used properly and that there are problems and the 15% apparently reflects average use within the general population. When used properly condoms have a failure rate of more like 1-2%.

The rates tend to be advertised the other way around for oral contraception, so you're getting the 'perfect use' failure rate rather than the 'typical use' one, and there are arguably more ways for it to be used incorrectly than condoms and it's less obvious when it's not working (whereas a broken condom is usually pretty evident). It's likely that at least some people aren't using it perfectly even if they think they are (because of lack of knowledge or because their biology is just working against them). I don't know the 'typical use' failure rate for oral contraceptives but it will be enough to account for more pregnancies than you might expect.

We were taught in undergrad biochem that taking large amounts of vitamin C can also affect the pill's effectiveness, not while you're taking it but when you stop. Not very well known, not often told to people by their doctors (because most doctors here don't discuss vitamin usage with patients) and enough to supposedly cause the occasional pregnancy during cold and flu season. Those classes were a few years ago now so this may have since been discounted, but it could be another thing to take into account.
posted by shelleycat at 8:33 PM on July 30, 2007

I believe that a bout of diarrhea shortly after taking the Pill (as in, before it's absorbed) can cause the same decrease in efficacy as vomiting right after, but it's not as natural of a connect-the-dots sort of thing as throwing up.
posted by bijou at 11:16 PM on July 30, 2007

I am one who tends to question nearly everything, including most TV "exposes" and a LOT of TV news, until shown proof. That said, I recently saw a "Dateline" show about the proliferation of fake medicine entering the U.S., mainly from China (smuggled in things like stuffed toys) but also via Internet sales. Even a medical expert had a tough time telling fake Viagra from the real deal. The counterfeiters even had packaging w/serial numbers, etc. that looked like the real thing. In addition, pharmaceutical wholesalers passed along some fake stuff to pharmacies, which dispensed the drugs unknowingly.

Could it be your 3 pregnant pals were given faux BC pills?
posted by Smalltown Girl at 11:21 PM on July 30, 2007

Sorry. I meant to say 2 pregnant pals and 1 new mom. (And even if you're not in U.S., fake meds could still be entering your country.)
posted by Smalltown Girl at 11:23 PM on July 30, 2007

Just as anecdote, I was conceived while my parents were using the best contraception available at the time: combined cervical cap and condom. Nothing is foolproof.
posted by jokeefe at 12:08 PM on August 3, 2007

I also had a friend who got pregnant after a tubal ligation.
posted by jokeefe at 12:09 PM on August 3, 2007

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