Time of Conception?

Updated on August 23, 2010
M.F. asks from Cleveland, TX
14 answers

This is a really weird question, but on Tuesday I found out I was pregnant. I took two home test and they both came out clearly positive. The first day of my last period was July 24, I have it written down. According to my google search (various sites) a pregnancy test is not even suppose to come up positive yet. I think the approximate date of conception was August 8th. I just want to get my dates right because with my last pregnancy I had to be induced because of high blood pressure and it was important the baby made it to at least 37 wks. Towards the end those weeks really count. I am feeling pregnant but is it possible to get a false positive? Or have these home tests just come a long way? I don't have an appointment for another month and half. Can someone shed some light?

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answers from Dallas on

There is NO such thing as a false positive only a false negative, so congrats to you :-) As for the date of your last period, are you sure it was a regular period and not a short one? A short one COULD indicate that it was implantation bleeding and not a regular period. Also-- some women actually have period like bleeding all through their pregnancies, or at least through part of it, which can totally throw estimations on when you conceived off! I will tell you something though, each pregnancy you have can be completely different, so if you had morning sickness last time you were pregnant and you haven't been sick this time, it definitely doesn't mean you can't be FURTHER along than you think! Girl, I think you conceived last month not this month, is that possible? There really doesn't seem to be a way that a test could come up positive THIS soon if you truly did conceive then! But then again, maybe you ovulated a different time than you thought? Anyway hope I helped, let us know how far along you are when you find out!

1 mom found this helpful


answers from Los Angeles on

My daughters and daughters-in-law have gotten positive results within a month of their last period. I would say your tests are correct.

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answers from Seattle on

Unless you've just had a miscarriage or are on fertility drugs, a positive means you're preggers. Congratulations!

Not EVERYONE produces enough hormone to read prior to missing, but many (if not most) women DO produce enough up to a week+ before they're due to miss. My family runs "hot" as far as hormones go, so 10 days before missing a period we can test positive. Others wont show up as positive for up to 2 weeks or more AFTER they've missed a cycle.

Also, dehydration helps (hence why some tests say the "best" time to test is the first pee of the day). The darker your urine is the more concentrated it is the easier for the test to read any hormones in it.

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answers from Cincinnati on

A false positive is really really really unlikely. The pregnancy tests detect the HCG hormone (the one used to make your baby grow). There is no other reason for your body to make this hormone outside of pregnancy. Sooooooooo... if the test is finding some HCG then WOO HOO!!! Congratulations Mama! Looks like you're having a baby!

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answers from Kansas City on

They do not use a date of conception to figure out how far along you are. Funny story- I concieved the day my husband came home from a six month deployment and for the longest time he swore the baby wasn't his because the doctor said I was 11 weeks but he'd only been home 9! Of course, when he popped out, there was absolutly no mistaking that kid was his (of course, I already knew that!). They will go by the first day of your last period, July 24th. Start counting up from there. Congratulations!!

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answers from Chicago on

The new pregnancy tests give accurate readings sooner than just testing when you miss your period. First Response advertises that you can "know" 6 days sooner. So I would have to say, congratulations! If you are still unsure you could wait until a day after you are supposed to get your period, and test again. Good luck!



answers from Norfolk on

I won't repeat what the other answers have said, other than congratulations. I will add that ovulation is not a constant between all women. The average is probably 14 days into your cycle, with conception and implantation occurring in a three day window around ovulation. Your ovulation could have occured earlier than is "typical". Also, many at home pregnancy tests claim accuracy up to 5 days before your missed period.

The best way to determine gestational age is vaginal ultrasound between 6 and 9 weeks gestation. Use your best guess and see if you can get an ultrasound for that time period. If your regular OB can't accomodate you, they may send you elsewhere just to make sure they have the estimated due date as accurate as possible.

Good luck and best wishes.



answers from San Francisco on

Congratulations! It is very rare to have a false positive-- Can you get in to see your doctor sooner? At least an ultrasound will be much more accurate to get measurements and dates to guess how far along you are. Congratulations!




answers from Philadelphia on

There is a false postive, i had one, very rare though. (due to blood in the urine i think)

You are pregnant :) Congrats! The tests for me showed positive a few days before period was due.



answers from New York on

sounds normal to me, 28 days is average but many times women ovulate sooner or later. tests sometimes do 5 days before your missed period. you may have just ovulated earlier, like 11 days after your last period, which is normal. i dont ovulate in my cycle until day 22 or more. i wouldnt worry, 2 tests with false positives is rare, and you are only talking a few days easily explained by earlier ovulation.

since you have concerns, once you go to the doctors, just mention you "think" that was your last period around that day but arent sure, then they usually will do an ultrasound to make sure and the ultrasound is pretty exact at the early times.

around here, doctors usually see patients earlier in the pregnancy.



answers from Honolulu on

You are probably most pregnant.

How come you can't get into see your Doctor earlier?
Is the OB/GYN that busy?
I would call them back and see if you can come in already.



answers from Raleigh on

I knew the day of the conception of our 3rd baby, and the u/s tech was able to tell how far along I was to the day:) Counting from period was always off by a week or more.



answers from Houston on

I understand the anxiety that comes with needing to have these details straight. Guess what--no matter what you say about the time, what the doctors use to determine the time is the rate of development. When they say that the baby has to be at least 37 weeks, what they're saying is that the development has to look like what they expect at 37 weeks, based on their experience. I think that you should go to the doctor and see where the little one is developmentally and keep your calendar with that.

I am pregnant now and KNOW with certainty my date of conception (absolutely no chance that it was before). Yet, the doctors still tack on that two weeks in front. My fertilized egg is only 17 weeks old right now, but the doctor's calendar shows 19 weeks because of the two-week automatic addition, and the ultrasound shows about 19.5 to 20 weeks, because this sucker is growing and active. Go from the time that your doctor gives you--unless you know otherwise FOR CERTAIN--and then just keep up with the development. That's what it's about, anyway, whether or not your baby is developed enough to come on out.

Congratulations and good luck to you!



answers from Laredo on

I had my last cycle on december 12 of 2009 so according to the doctor and websites I conceived on December 26. I took a pregnancy test just about three weeks later and both came out positive as well. I went to the doctors the following week and they confirmed with a urine and blood test. So I wouldnt think that it is too early to tell.
Alot of it has to do with the time of day that you do the at home pregnancy test. If you do it before you start drinking lots of fluids for the day the tests are more likely to be accurate.

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