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Had unprotected sex. Started irregular periods. After how long should I take home pregnancy test?

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Practicing since : 1999
Answered : 1671 Questions
Had period from August 2nd - August 6th. Next was on, August 20th - Sep 3rd.
When should i be expecting next period?
After how many days should i be worried if no period?
After how long should i be taking home pregnancy test?

Earlier, before August, used to be a 28 day cycle.
No contraceptives, no pills.
Unprotected sex on Sep 20th.
Posted Wed, 17 Oct 2012 in Early Pregnancy Signs and Symptoms
Answered by Dr. Timothy Raichle 2 hours later
Hello, I would be happy to answer your question today.

So from what you are describing, I will summarize your situation:

1. You are a healthy 23 year old
2. You previously had regular 28 day cycles
3. You had unprotected intercourse on 9/20
4. You had a normal period on 8/2 (lasting 5 days)
5. You had an early period on 8/20 (beginning on cycle day 19)
6. Assuming that the 8/20 period MIGHT have been normal, your next cycle would have been due on 916 - so you are currently late.

Now you did not mention if you had intercourse unprotected at any time prior to 9/20. If this is the case, please update me so that I can give you the most accurate answer. With regard to WHEN to do a pregnancy test, you should do one now and AGAIN two weeks after that episode of unprotected intercourse on 9/20.

Please let me know if this answers your question - Dr. Tim
Above answer was peer-reviewed by
Follow-up: Had unprotected sex. Started irregular periods. After how long should I take home pregnancy test? 1 hour later
Had unprotected intercourse on 9/8, 9/9, 9/15, 9/16, 9/19, 9/22, 9/23

Home pregnancy test on 9/23 with noon sample was negative.
Answered by Dr. Timothy Raichle 9 minutes later
Assuming that the 8/20 period was POSSIBLY normal but early, this would have placed the intercourse on 9/8 as well beyond when you would have ovulated.

That being said, you had such an unusual cycle, that I am not sure you can really know exactly when you did ovulate.

So, I would repeat the pregnancy test two from 9/23. If it remains negative, then you are definitely not pregnant. By then, if you have gotten your period, this will be further confirmation that you are not pregnant. If you still don't get your period, and the test is negative, then it would be time to see your doctor to figure out what is going on.
Dr. Tim
Above answer was peer-reviewed by
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