If your daughter looks fine and healthy I don't understand why you would even need an ultrasound so often. That sounds a little fishy to me. Unless you are at high risk or the baby has some sort of defect that really needs monitoring, you shouldn't have a lot of ultra sounds because it isn't good for the baby's development, plus it's expensive!
Please read the info on this page and I put the relating part copied below:
Information on Prenatal Technologies
The process of getting information on a technology can be tricky so a couple of examples will be given to illustrate how to go about it. While pregnant it might be a good idea to test your skills at getting information on a technology and to see how willing the midwife, nurse or doctor is to provide full unbiased information.
It is likely a routine ultrasound scan will be suggested fairly early on in your pregnancy. This presents a perfect opportunity to ask a few questions. "What is the chance the scan will make things worse? Is such a scan safe?" If the answer is a flat "yes, ultrasound scanning during pregnancy is safe," alarm bells should start going off in your head because you are not getting the full information. You must then ask "Show me the data on the safety of prenatal ultrasound" in order to check on what you may be told about the data on the safety of prenatal ultrasound. As a scientist I can assure you that the only correct answer to your question is "We don't know because there is not sufficient scientific data to prove the safety of prenatal ultrasound." Some research has shown the possibility that ultrasound can cause slowed growth of the fetus while still in the uterus. Other research has shown the possibility that some children who have been scanned while still in the uterus may later have mild neurological deficits. We need more study of both these possibilities. But from a scientific viewpoint, it is impossible to say today that ultrasound scanning during pregnancy is perfectly safe.
The next question to ask when ultrasound scanning is proposed to you is "What is the chance that a scan will make things better?" When you are told that one reason for the scan is to look for defects in the fetus, ask: "What is the chance a defect will be correctly identified (true positive screening test) and what is the chance a defect will be incorrectly identified (false positive screening test)?" If your provider cannot or will not answer this question, watch out! Again so you can check on what you may be told, here is the best scientific data: If one hundred pregnancies are routinely screened with ultrasound to look for a defective fetus, two out of the hundred will have a true positive result (i.e. the scan says the fetus is defective and it truly is defective ) and one of the hundred will have a false positive result (i.e. the scan says the fetus is defective but it is not defective, it is a normal fetus). So if all women with a positive scan are offered therapeutic abortion, for every two defective fetuses aborted, one normal fetus will be aborted. How many women are told this before they are offered a routine prenatal ultrasound scan?
Your next question when ultrasound is suggested should be, "Is there a better chance my baby will survive the pregnancy and birth if an ultrasound scan is done, and what are the data?" The correct answer is that a large study in the United States of over fifteen thousand pregnant women showed no improvement in the mortality rate of the babies if ultrasound is routinely used during pregnancy.
One scientist published the following summary of the present state of the art on routine prenatal ultrasound scanning: "The casual observer might be forgiven for wondering why the medical profession is now involved in the wholesale examination of pregnant patients with machines emanating vastly different powers of energy which is not proven to be harmless to obtain information which is not proven to be of any clinical value by operators who are not certified as competent to perform the examinations." For all these reasons, the American College of Obstetricians and Gynecologists, the American College of Radiology and the US Government's Preventive Services Task Force all recommend against routine ultrasound screening of low risk pregnancies. This is the type of unbiased, scientifically sound information you need to make informed choices about technology used on you during pregnancy.
http://www.childbirthsolutions.com/article
s/pregnancy/techinbirth/index2.php
And the above posters are right...the reliability does go down as the baby gets older...it's harder to tell thing with the ultrasound.
I mean when I had my 21wk U/s she measured at exactly 21wks and now I go in for my 26wk u/s and they tell me that she is measuring at 24wks....what happened??
