Best Answer

Yes, During an ultra sound they measure the length of the baby, the limbs if visible, head circumference etc.. then calculate an expected delivery date. An ultrasound is accurate to within a couple of days if done at 8 weeks. At 20 weeks it is accurate to within a week. After this babies grow at such diffeerent rates that it becomes increasingly less accurate.

User Avatar

Wiki User

โˆ™ 2006-03-02 06:33:53
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: Is an ultrasound more accurate in dating of pregnancy especially if you do not know your LMP?
Write your answer...
Related questions

You were 16 weeks pregnant your ultrasound said that the baby size was 18 weeks which one should you do by?

The ultrasound dating has excellent and precise estimation of gestation especially if done in the first trimester (first 12 weeks). After 12 weeks, its accuracy goes down. However, compared to dating according to menstrual cycle, the ultrasound would be more accurate.

When they do a sonogram can they know exactly when you got pregnant?

If the ultrasound is done in the first weeks of pregnancy it is possible to date the embryo within a few days, an ultra sound done later is not as accurate for dating purposes.

How early can you tell if your having triplets?

With a dating ultrasound done in early pregnancy, about 5 to 6 weeks.

How accurate are dating scans in pregnancy?

They claim to be completely accurate but actually can be one week off either way

How accurate are the ultrasounds for dating a pregnancy?

My wife told her doctor she didn't know when her last mp was, so he sent her for an ultrasound! She lied, we just wanted 2 get an early ultrasound, and it was exact 2 the day and that was at 5 weeks 4 days! Our 1st baby measured within 5 days thru the entire pregnancy, and that was as early as 8 weeks and as late as 26!

Could i be father along in my pregnancy than what im told consdering i had irregular period when my periods normally last 5 days but lasted a week with spotting?

Yes. You should tell your Dr so that they can preform an ultrasound to provide you with more accurate dating.

How off can an ultrasound be on the date of conception if you have an ultrasound at 7 weeks?

Aftere having had two healthy babies and one miscarriage, I have found ulrasounds to be extremely accurate in dating a pregnancy. My OB is now only performing the initial ultrasound at 8 weeks due to the fact that so many pregnancies end in spontaneous miscarriage (20% of all pregnancies). They would not have patients wait until 8 weeks if they felt the process would inaccurately date the pregnancy. Dating is important in order to make sure that screenings are done at the appropriate times for accurate results (quad screen, glucose test, group b strep swab, etc.). I hope this helps you and good luck!

What does BPD mean on ultrasound?

Biparietal diameter (BPD) is the diameter across the developing baby's skull, from one parietal bone to the other. The measurement is useful in dating the pregnancy and estimating fetal weight after about 13 weeks of pregnancy.

Radiometric dating or carbon dating which is more accurate?

You cannot say that carbon dating is more or less accurate than radiometric dating since it is a form of radiometric dating

For what purpose do geologists use relative dating?

It remains a useful technique especially in materials lacking radioactive isotopes. Relative dating by biostratigraphy is the preferred method inpaleontology, and is in some respects more accurate

If an ultrasound estimates that you are seven weeks pregnant could it be off by a week?

Not really. Babies grow at pretty precise rates and therefore conception is pretty easy to answer at this early in your pregnancy. You are more likely to have your dates mixed up or that you conceived at a different time than you thought. Yes the date could be off a bit but ultrasound dates are usually pretty clear and accurate on dating embryos. Its all down to the measurements taken of the embryo and last period etc, that give a estimate of the conception date. When an ultrasound shows you are 7 weeks pregnant it actually means you are 5 weeks from conception. Pregnancy is on average 40 weeks from the start of the last period. This is because in the days before ultrasound this was the only date we knew. You don't actually conceive until 2 weeks after this date.

Which sonogram is more accurate 7 or 18 week For example at 7 weeks you were 7 weeks and 3 days At 18 weeks you were 19 weeks 7 days Which is correct?

Because an ultrasound at 7 weeks and one at 18 weeks use different methods for estimating gestational age, they have different levels of accuracy. In general, a skilled sonographer's 7 week ultrasound is more accurate for dating than a skilled sonographer's 18 week ultrasound. Talk with your health care provider for information specific to your situation.

Is radioactive dating a scientific theory?

No, it is a method of dating materials that is very accurate.

What is a weakness of relative dating?

It is not always accurate.

Is stratigraphic dating accurate for dating fossils?

Carbon dating and radioactive dating are more effective, assuming those arn't the same thing. =]

Is radiocarbon dating accurate?

Radiocarbon dating is incredibly accurate. However, on occasions it may not be particularly precise and the date given my include a range of several decades.

What is the most accurate way to date a fossil?

Carbon dating

What are the release dates for Pregnant in Heels - 2011 The Pregnancy Dating Dilemma 2-8?

Pregnant in Heels - 2011 The Pregnancy Dating Dilemma 2-8 was released on:USA: 3 July 2012Pregnant in Heels - 2011 The Pregnancy Dating Dilemma - 2.8 was released on:USA: 3 July 2012

Does radioactive dating produce exact results?

No, radioactive dating does not produce exact results. No form of radioactive dating produces exact results. But results can be gotten that are surprisingly accurate. As a "for instance" we might look at uranium-lead dating. This dating method can deliver results accurate to a million or two years in a billion years. That's about 0.1 to 0.2 % or so.

The most accurate age of a fossil can be found using?

relative dating

How can the most accurate age of a fossil be estimated?

Carbon dating techniques

Is kelly rowland dating trey songz?

not accurate thanks for asking

When given a dating ultrasound do you need to subtract two weeks for an actual date?

When you have a dating ultrasound you are given an EDD (estimated date of delivery) If you count back 40 weeks from this date it should be about when your last period was. If you do not have a regular cycle they may not correlate exactly. 38weeks back from your EDD is approximately when you conceived.

If an ultrasound gives you a date of how far along you are is it possible you could have been pregnant 5 weeks ago and still had your period and the ultrasound be off?

The ultrasound doesnt give you the date. It is estimated by the days you give to the doctors to help, narrow down the date. The first day of your last period and how long you've missed help them in determining your conception date. The picture shows them an image of a fetus and they use that picture to say at what developmental stage the baby is in. Anything is possible.AnswerContrary to the opinion above, the ultaasound does give you an approximate date of conception. By comparing the results of millions of ultrasounds physicians can calculate the age of the fetus based on head diameter, bone length, and other measurements on the fetus. They are usually accurate to within two weeks of when you are due to deliver. Since some women have irregular periods, it is not always possible to calculate the date based on the first day of the last period. Trust the ultrasound! ANSWERI just wanted to add to the above answer. A patient's Last mentrual period is accurate if the patient has a regular mestrual cycle, but this is not the case for many women. Therefore, it is not the most accurate source for fetal age. Ultrasound is the most accurate dating tool for fetal age. The measurement of the embryo (crown rump length) up to 12 weeks gestation is the most accurate. The rate of growth of a fetus will be based on that early measurement for the remainder of the pregnancy. It allows physicians to monitor the growth of the fetus which in turn gives them an estimated due date as well as help them diagnose growth abnormalities such as IUGR (Intrauteriune growth restriction).

What is used to provide the most accurate measurement of a fossils age?

Radioactive Dating