Heather Corinna replies:
I'm very forgetful, and at times I forget to take the pill. My boyfriend and I have unprotected sex, so I was wondering if I miss a day with out taking the pill what are my chances of getting pregnant? How long before the sperm dies?
Missing one every now and then so long as you make it up within a day or so won't likely compromise your effectiveness all that much, but if you're missing a few pills regularly, that's when you start to look at viable pregnancy risks. And in the case that you're on a minipill, a progestin-only pill, it's an even bigger deal, as it matters what time those pills are taken, not just that they're taken each day. If you're a few hours late routinely, without even missing pills, you can be at a reasonable risk of pregnancy.
The pill isn't a good choice for someone who just can't remember to take them every day, and ideally, can't take them around the same time daily. While it's one of the most commonly prescribed forms of hormonal birth control, it's hard for an awful lot of people to take that pill on time or every day without fail, especially young people whose schedules tend to be more erratic or are trying to hide pill use from parents.
That's why there tends to be a lower rate of effectiveness in typical use with the pill among teens. As shown here, one study found that teens' ability to use the pill properly was as low as only 45% with the first three months of use, and 33% with one year of use. That's pretty dismal.
One of the most important jobs of any healthcare provider who is helping you to find a method of birth control is to find out if that method is going to be the best one for you, not just in terms of risks and side effects, but when it comes to what methods are methods you will or will not be able to use properly. Timeliness is a biggie when it comes to the pill, so in counseling a client who wants that method, it's vital that we find out if they're forgetful in their daily lives or not, and make sure that if they are, we suggest alternatives which will probably be more effective choices for them.
So, you have two options: you can either find out a way to take that pill every day without fail, or you can talk to your healthcare provider about switching to a method which is going to be a better fit for you. Additionally, no matter what method you use, your boyfriend can share the responsibility of birth control with you by backing up with condom use. That way, if you miss a pill, you're still covered. Considering that the pill effects your body far more than a condom could dream of doing to his, it's a pretty small concession for any male partner to make.
If you really want to stay on the pill, try finding a time where you do something around the same time every day, like brushing your teeth in the morning or at night, or when you have lunch, and get in the habit of taking your pill in conjunction with that routine. There are also pill cases you can buy which come with an alarm to help remind you to take them.
Or, you can switch to a different method you don't have to remember to take, apply or change as often. Both the contraceptive patch and the vaginal ring, for instance, are combined hormone methods like the combination birth control pill. If you haven't had side effects you don't like with your pill, so feel a combination hormonal method is otherwise working for you, you might want to look into those. You only have to remember to change the patch once a week, and you only need to remember to change the ring once a month. You also have the option of considering progestin-only (that's one of the two hormones in your pill) methods you have to remember even less: Depo-Provera only needs to be injected once every three months, and Implanon, the new contraceptive implant, once inserted can remain in and effective for up to three years. For a forgetful person, I'd not suggest methods like cervical barriers, since it's hard enough to remember to take a method in your average day: so if that's tough, remembering to put something in in the heat of the moment will likely be even trickier for you. So, if you don't feel like you'll be able to take the pill every day, or you try the suggestions above and still can't get in the swing of it, I'd suggest you talk to your doctor or clinician about some of these other options.
Per your sperm question, sperm can live inside the vagina for anywhere from 2-5 days after ejaculation. But how long they can remain viable in your vagina is a bit of a non-issue here. You can't chart your fertility when on the pill, since it alters your fertility cycle (and that'd also mean remembering to chart daily), so knowing when you're likely to be fertile should you release an egg due to not taking the pill on time would be a challenge. But if you stick with the pill and miss one or two, you'll want to have your partner use a condom as a backup method of birth control for the whole of that cycle, until you start a new one.
Here are some extra links -- including a means for you to get a good idea of what method might be a better choice -- for you: