I had sex the last day of active pills for


Q: I had sex the last day of active pills for my pack. Three days later (during placebo week) I was diagnosed with strep and started taking amoxicillin. Once I started antibiotics we used a backup method also. Is it possible I'm pregnant? I took a test at the end of my placebo week and it was negative. I was suspicious because I have a very light, almost non-existent period during my sugar pill week. I assumed that would happen though because I had just finished two consecutive packs without taking placebos. Also worth noting, I didn't miss any pills.


A:   Hello,

Thanks for writing to us.

I have read your case and can understand your concern.

Pregnancy is more likely to occur when intercourse is done in female's ovulation period. Pregnancy is technically only possible during the five days before ovulation through to the day of ovulation.

These six days are the ‘fertile window’ in a woman’s cycle, and reflect the lifespan of sperm (5 days) and the lifespan of the ovum (24 hours).

If a woman has sex six or more days before she ovulates, the chance she will get pregnant is virtually zero. If she has sex five days before she ovulates, her probability of pregnancy is about 10%.

The probability of pregnancy rises steadily until the two days before and including the day of ovulation.

At the end of the ‘fertile window’, the probability of pregnancy declines rapidly and by 12-24 hours after she ovulates, a woman is no longer able to get pregnant during that cycle.
Ovulation happens about two weeks before the next expected period. So if your average menstrual cycle is 28 days, you ovulate around day 14.

As you mentioned you did intercourse in the placebo week (considered as safe period), the pregnancy is least likely to happen during that time. So, your test came out to be negative.

Reduced menstrual flow is a common side-effect of hormonal contraception methods, such as oral contraceptive pills that you are taking as the relatively low estrogen contained in most hormonal contraceptives decreases endometrial growth, so there is relatively little endometrium left to be shed during menstruation.

Hope I could solve your query.
feel free to write back.

Comments / Follow Ups

Patient: I understand all of that. But isn't the point of the pill for women to not have a normal menstral cycle meaning that skipping a pill at any point of taking a drug that interacts with the pill could cause you to ovulate at strange times? Probably over thinking this. I've just never taken antibiotics and the pill and was concerned it may make effect how it works and potentially cause ovulation within the five day period.
Doctor: HELLO,
Thanks for writing back.
A 28-pill pack has 21 hormone pills. The additional seven pills are placebo pills (containing sugar or iron) to help the user stay in the habit of taking a pill every day.Since you had missed the placebo dose it is less likely to have any effect on ovulation . Once you get menses however scanty they were it indicates you are not pregnant. As I mentioned before scanty menses could be because of OCPS you take.
So though OCPS prevent ovulation and missing them can cause pregnancy but since your dose was missed when you had to take placebo it is less likely that you would be pregnant.
Hope I could solve your query.
Feel free to write back.
Patient: I did take my placebo pills when I was taking antibiotics. Prior to that I had taken two consecutive packs with no placebos in between.
Doctor: Hello,
Thanks for writing back.
Since you got menses it is less likely that you would be pregnant.
You can get ultrasound done to rule out pregnancy.
Hope this helps.
Feel free to write back

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