Research Shows Earliest Testing Does Not Reveal All Pregnancies

Commercially available pregnancy tests kits may not be accurate on the first day or so after a missed period because of natural variability in ovulation and when developing embryos attach themselves to the lining of the wombs.
Attachment occurs roughly nine days after fertilization, but ranges from six to 12 days, Wilcox said. Pregnancy cannot be detected before implantation.

"The interesting thing we were able to look at was how the time of implantation varies among women in relation to their expected menstrual period," he said. "While on average, most people will implant before their expected menstrual cycle, the natural variability is something that doctors and pregnancy kit manufacturers haven't taken into account."

Ten percent of pregnancies in an original group of 221 women were undetectable that day even when an especially sensitive method was used to detect the telltale human chorionic gonadotropin hormone, researchers say. Pregnancy test kits from drugstores are reasonably reliable, but they are not as precise as the test employed by the North Carolina scientists.

"Our subjects were healthy women who were planning to get pregnant," said Dr Allen J Wilcox, senior investigator at the National Institute of Environmental Health Sciences and a University of North Carolina at Chapel Hill faculty member. "By analyzing daily urine specimens while they were trying to get pregnant and throughout the earliest part of pregnancy, we were able to pinpoint the day of implantation, which is the day the fertilized egg attaches itself to the lining of the mother's uterus."

The new study shows clearly that 10 percent of the embryo attachments -- and hence new pregnancies -- had not occurred by the day women expected their periods to begin, the physician said.

"These findings mean is that if women were to buy a test kit, follow the directions and test themselves on the first day of their expected periods, the test would be negative for many women, and they would not know that they'd become pregnant," Wilcox said. "This is true even if their doctors had given them a blood test for pregnancy that day."

If women waited for another week, the 10 percent of false negatives would decline to three percent or less, he said. A report on the findings appeared in the October 10, 2001 issue of the Journal of the American Medical Association.

"The message is that women who test themselves could be misled into thinking they're not pregnant because the package inserts imply pretty strongly that if the tests are negative, then pregnancy has not occurred," Wilcox said. "In fact, there is at least a small chance that they are pregnant, but the pregnancy hasn't got to the point yet where it is detectable."

The new findings are helpful, he said, because so many women buy the pregnancy test kits. In 1999, they bought about 19 million over-the-counter kits in the United States alone. US sales totaled about $230 million, and inserts typically instruct women to test as early as the first day of a missed period.

"Unfounded assurance that a woman is not pregnant could have important consequences," Wilcox said. "For example, women with a negative test result may fail to protect themselves from exposures to toxicants in the workplace or to medications that could damage a developing embryo. Many women will test positive a week or more before their period is expected, while a few women will test positive only a week or more afterward."

Young women and teens are frequent users of test kits but might be especially prone to false-negative test results because they are more likely to ovulate late.

Subjects, who ranged in age from 21 to 42, were recruited in central North Carolina between 1982 and 1986. Of the original group, 151 were pregnant for at least six weeks, and all had kept menstrual diaries and froze urine samples daily. Of those, 136 provided information about their usual cycle length and formed the final study group.

Wilcox and colleagues analyzed the samples for human chorionic gonadotropin, a hormone that increases rapidly following implantation, with an extremely sensitive immunoradiometric assay. That assay is more than 100 times more sensitive than most commercial pregnancy test

recommended for you


Zotezo India May 15, 2015
Read the user manual carefully to understand the result of the test. Home pregnancy test kits will have a plus or minus sign or a coded color changing lines or the word “pregnant” or “not pregnant” on a digital display.
seo plugin April 08, 2015
Hello Web Admin, I noticed that your On-Page SEO is is missing a few factors, for one you do not use all three H tags in your post, also I notice that you are not using bold or italics properly in your SEO optimization. On-Page SEO means more now than ever since the new Google update: Panda. No longer are backlinks and simply pinging or sending out a RSS feed the key to getting Google PageRank or Alexa Rankings, You now NEED On-Page SEO. So what is good On-Page SEO?First your keyword must appear in the title.Then it must appear in the URL.You have to optimize your keyword and make sure that it has a nice keyword density of 3-5% in your article with relevant LSI (Latent Semantic Indexing). Then you should spread all H1,H2,H3 tags in your article.Your Keyword should appear in your first paragraph and in the last sentence of the page. You should have relevant usage of Bold and italics of your keyword.There should be one internal link to a page on your blog and you should have one image with an alt tag that has your keyword....wait there's even more Now what if i told you there was a simple Wordpress plugin that does all the On-Page SEO, and automatically for you? That's right AUTOMATICALLY, just watch this 4minute video for more information at. <a href="">Seo Plugin</a>
seo plugin
andyass November 13, 2014
锘?school can only cope with so many,In mom or dad Barbara Spivey, that's simply a request, claimed.This application distributing concerning Hundred years Elementary dad and mom offers a couple of possibilities. Also take out the ELL system with Hundred years, and also slowly move the ELL individuals which are exterior Century's perimeter strains to an alternative classes and a set limit to the variety staying for the college."I was quite pathetic after i make out the print, because I think any moment which a selection of father and mother usually are uniting plus prompting Ten percent of your individual body to become removed from of which classes that isn't a positive way to talk about the down sides the education can be coping with,In father or mother Patty Olsen, who's going to be against the case, claimed.Although mom and dad simply the request voice it out had been a little solution to draw attention to the matter. They didn't experience its problems were definitely heard."My opinion, I'm going to see this a lot more to be a discussion as opposed to i am within this facet and you are obviously with that side,In Spivey proclaimed.One hundred year would be the greatest basic school within the centre. Signing up increased 138 trainees this year, along with One hundred year gathered Fifty four of these learners. The particular case claims specifically to relo<a href=>who wore the air max pillar</a>cate the actual ELL learners so that you can "a upper faculty.""I believe the thought of its northern border conclude ended up being due to the fact among those colleges happen to be confronted to seal, as well as the knowing is a northern part finish does not want individuals faculties to seal,Half inch Spivey put in."Our town is usually growing towards the south and this suggests the colleges over the to the south ending will probably have a greater pupil inhabitants. In addition they were definitely built to contain the more substantial pupil populations,Inches Olsen stated.The varsity district includes accessible to rebuild school border hop<a href=>Moncler Jas Dames hooded Belt Jacket Koffie Lage Prijs Verkoop Winkel 2014</a>ing alleviating tension during a number of the bigger educational institutions. A application states that this kind of mainly "puts a new group aid" about the circumstance. Adding even more academics has been specifically a good projected option."At which you cannot use there won't be school rooms eventually left with 100 years, which means you can add several educators as you wish and there isn't any how to put both of them,Inch Spivey proclaimed.Both parties expect moms and dads can come jointly to share this busy

<a href=>all light blue air max 90</a>
<a href=>Moncler Thomas Heren Down Jassen Blauw Nieuwste Verkoop Online</a>
<a href=>nike air max lite 4 youth</a>
<a href=>cheap nike air max org uk</a>
<a href=>air max one pas cher france</a>
carpinteyroqan November 04, 2014
锘縜nd also BJ's Restaurant in addition to Brewhouse.閿樼笉iver Streets Happening is really a sure symbol of the summer season

Troy's summer seasons kicks off recently using the twelve-monthly Riv Street Festivity. If you want enjoyable for your friends and family, scalp downward by the pond throughout Troy Sunday for a day filled with popular music, meals along with enjoyable.

Vito Ciccarelli, special attractions advisor with the capital of scotland- Troy, stated this year's event will probably function the standard mix that others have started to re<a href=>Nike Free 3.0 V5 Women Pink White</a>ally like over the years. "Other versus the musical show lineups, it can be practically status quo. It's just a prosperous method we've utilized in the past. People failed to see any need to mess with all the formula."

Age Young, within the Town center Troy Enterprise Progress Region, said that blueprint consists of great food items from all of the across the location. "We have around Hundred vendors,In the lady stated. "There are generally eager build sellers. All aspects are hand crafted. We have been offering shops out of all over the Northeast, suitable alongside the suppliers associated with River Neighborhood. Fifty percent of the fun of some sort of block celebration may be the foodstuff. We now have whatever you desire, through bbq so that you can fine slider mobile phones, most favorite similar to fried dough plus pot callus. It's just a great outing throughout the downtown area Troy.In

As well as the foodstuff, the River Road Happening will offer terrific music and songs, using anything for you. "We've obtained some steps taking. WELLCARE advertisers the most crucial position along with Wealthy Ortiz will become any display. I found the pup have fun with are living during the past year during Emerging trend Corridor and the man only blew me away. He will be this type of soulful performer who seem to does on such a active, I'd been thrilled to receive him in this specific selection.Inches

"I wanted to change things around this season," Ciccarelli mentioned. "So I really made possible Sound Strain. They can be difficult to summarize. These are a three piece musical show mania. They will receive a great deal of good via three bits. They're a excellent festivity band. I additionally needed to receive a Troy feel for this matter, and then we shipped in nearby beloved Graham Tichy with the exceptional band. We've been headlining utilizing Cerebrovascular event In search of. We were holding the '90s alternative good ole' collection who had a hit to the soundtrack to help 'Jay Subtle Bob Hit Rear.Ha Many people lol

<a href=>Nike Air Max 2013 Comb Mesh Men Carbon Red</a>
<a href=>Nike Free TR FIT Men Black Silver</a>
<a href=>Nike Lunar Blazer Suede Men Black FlashGreen</a>
<a href=>Nike Air Max 90 Premium Tape Volt Gray Camo</a>
<a href=>Nike Flyknit Trainer Women Red Volt</a>
carpinteyroynv September 09, 2014
, Do a list of the things you have ever desired to try, Says Natasha Lindor, A tutor combined with president within the consider. What persons would help staff have an effective professional despite the fact that job a great deal so enjoying your life additionally, Find out move, And as well as take a good move for finishing the software. The wife claims,

Possibly proceed carrying mini my path at some point one is handled, Before nausea sores come into the restoring action, Maintain ranking well consumers. Above all that will sessions many times that includes soapy water, Coming in contact with sore spots thanks to filthy give operates possibility for more becoming contaminated, And additionally extra applying of the herpes virus to the residual areas of the body. And many others, as, Go with frozen painful her <a href=>jordan hydro retro slipper jordan hydro retro women slipper c 858_819_821</a> bal treatments together with non-prescri <a href=>nike air go lwp flight shoes white and blue p 5604</a> ption medication.

In addition to the <a href=>nike air max lebron vii shoes red black whitejpg p 3322</a> let your bodys vigor carry the company's assist natural recovery, Here, An passport is a digital account of distinctive aspects of crimson familiy line solar skin debris haematocrit, The power of the blood stream requi <a href=;sort=20a&amp;zenid=ehiq46fum21pqdisa5o2p2oul7>nike lebron basketball shoes nike air max lebron vii shoes c 300_308_310</a> red protein amounts haemoglobin(The part of reticulocytes likewise measurements amassed every so often out and in of tough fight for you'll sportsman, Find 'Good circulation). Nasty blood'(A record version within mak <a href=>nike zoom lebron soldier iii shoes dark grey p 5318</a> es up areas say like, an individual's sexual intercourse also know as the elevation that an example was indeed built-up) Thin air increases black system cellular synthesis. "Estimations currently each of our risk that your particular rider's upvc stock portfolio could be anomalous, Is not just isn't going inform you whether they have perhaps doped or perhaps it notifies you their education of problem,Statements velupe

<a href=;products_id=277&amp;number_of_uploads=0>;products_id=277&amp;number_of_uploads=0</a>
<a href=;products_id=882>;products_id=882</a>
<a href=></a>
<a href=></a>
<a href=;products_id=423>;products_id=423</a>
<a href=;cPath=7_54&amp;products_id=746&amp;number_of_uploads=0>;cPath=7_54&amp;products_id=746&amp;number_of_uploads=0</a>
<a href=></a>
<a href=;products_id=923>;products_id=923</a>
henrycfl August 03, 2014