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How effective is Plan B in preventing pregnancy?

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Posted on Wed, 13 May 2015
Question: While having protected sex with my girlfriend, my condom broke, and I ended up accidentally ejaculating in her. Realizing the mistake, we immediately bought and used plan b within 3 hours. The only problem is we don't whether or not she was ovulating at the time. She said her period would probably be happening in about a week or so. What are the chances of her getting pregnant regardless of taking plan b immediately after the mistake?
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Answered by Dr. S Patra (13 minutes later)
Brief Answer:
Chance of pregnancy less than 1%.

Detailed Answer:
Hello,

Thanks for writing to us.

Plan-B is an emergency contraceptive pill and will give protection more than 95% against unwanted pregnancy if taken within first 24 hrs of sex.

If her period is due for 1 week, then it was relatively SAFE sex. In this case, her chance of pregnancy is extremely LOW or NEGLIGIBLE.

She will get a withdrawal bleeding like period within 5-7 days and it may coincide with her regular period.

Hope, it helps for your information. Practice safe sex and use contraception in future. Kindly, close the discussion if you don't have any other query.

Regards,
Dr S Patra

For future query, you can directly approach me through

http://doctor.healthcaremagic.com/Funnel?page=askDoctorDirectly&docId=63326
Above answer was peer-reviewed by : Dr. Pradeep Vitta
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Follow up: Dr. S Patra (5 minutes later)
OK, thank you so much for the speedy reply. My only other question is I've heard that plan b doesn't work if she is already ovulating. Is that true? She doesn't think she is, but I'd like to know just in case.
doctor
Answered by Dr. S Patra (2 hours later)
Brief Answer:
Post-fertilization action is quite weak.

Detailed Answer:
Hello,

Thanks for follow up query.

1) Emergency pill like Plan-B helps to prevent fertilization by inhibiting or delaying ovulation. It is the usual mechanism of action of such pills.

2) Post ovulation, these pills may cause endometrial changes (biochemical) that discourage implantation. Though, it is very much weak.

3) I suggest her to await for next coming period. If it is delayed more than 1 week, she must undergo one home pregnancy test to clear doubt.

Hope, I have answered your query. Kindly, close the discussion.

All the best and good luck.

Regards,
Dr S Patra
Above answer was peer-reviewed by : Dr. Vaishalee Punj
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Answered by
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Dr. S Patra

OB & GYN Specialist

Practicing since :2011

Answered : 4048 Questions

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How effective is Plan B in preventing pregnancy?

Brief Answer: Chance of pregnancy less than 1%. Detailed Answer: Hello, Thanks for writing to us. Plan-B is an emergency contraceptive pill and will give protection more than 95% against unwanted pregnancy if taken within first 24 hrs of sex. If her period is due for 1 week, then it was relatively SAFE sex. In this case, her chance of pregnancy is extremely LOW or NEGLIGIBLE. She will get a withdrawal bleeding like period within 5-7 days and it may coincide with her regular period. Hope, it helps for your information. Practice safe sex and use contraception in future. Kindly, close the discussion if you don't have any other query. Regards, Dr S Patra For future query, you can directly approach me through http://doctor.healthcaremagic.com/Funnel?page=askDoctorDirectly&docId=63326