How accurate is an ultrasound, Based on first day of last period I am 7 weeks, ultrasound says 5, why is this?

I am pregnant with my second child. My first pregnancy and delivery went awful. At the time of my last ultrasound the ultrasound dr measured my daughter to only be the size of a 36 week old which put my due date from February 25th to March 15th. Following that ultrasound I started having severe hypertension and only 2 weeks later started showing protein in my urine. I was then given an emergency c-section to only get help syndrome immediately after delivery. As far as my daughter's health she was fine other than the fact she had lost oxygen from the hypertension. She is now a year old and extremely healthy, but still small she only weighs 22lbs. At delivery she was only 5lbs and 18 1/4 inches. I just had my first ultrasound for my new baby. From my first day of last period I should be 7 weeks pregnant and due on April 2, 2008. I did not mistake the first day of my last period this time or the last. The ultrasound however shows the baby to only be 5 weeks. How is this? Considering my first baby was very petite is it possible that this baby is petite at 5 weeks. I am also high risk %26amp; seeing a high risk doctor, will he make me carry the baby to what the ultrasound deems as full term even if I run into the complications I had in the first pregnancy? I am very worried, I don't understand why even if I get the first day of my last period right I am still 2 weeks off. I also hope that this child is not suffering IUG in early term. Anyone know about this?|||Hun don't stress too much over date. It depends on when you ovulate as to how far along you are. I'm actually due about 2 weeks earlier then my dates say since I ovulated really early during the cycle I got pregnant in.


Also don't worry about your baby being "petite" My son is the same way yet extremely healthy.


If you run into the same complications with your blood pressure they will take the baby by c-section again if they can't bring your pressure down with mag sulfate. They are not going to risk loosing both of you due to seizures or stroke which is what happens when pre-eclampsia is not responded to aggressively. They may end up having you deliver early. There is no real way to know ahead of time if this will develop again.


I had HIP with my son before the third trimester started. I'm now 27 weeks with my daughter and no sign of a rise in blood pressure yet. Please do your best not to stress over it.


also I wouldn't worry about IUG this early. They'll probably do another US very soon and this baby will more then likely measure the appropriate amount of growth.|||i asked the same question about a week ago. according to my last period i'm supposed to be12 weeks right now but the ultrasound said i am 9 weeks. (weeks adjusted for the time that has passed since the ultrasound) . an RN told me that the ultrasound meassured from conception so u would want to go by ultrasound since the other method of figuring a due date is less accurate. plus from all the things i have been reading and watching on the discovery chanel tell me its too early for your baby to be a bit too small for its age. dont worry too much right now but ask ur doc at ur next ob visit.|||the ultrasound is correct, they are very very accurate if taken this early in pregnancy. there is no such thing as IUGR this early. if you develop preeclampsia again, you will usually not go to term. no reputable doctor would make you go to term if you indeed had preeclampsia.|||your Dr counts from the first day of your LMP but remember ovulation usually only happens 14 days after LMP that will give you a 2 week difference. I had a 3 weeks difference because my cycle was 35 days. Hope this helps you. Please don't fret as it won't help you or your baby. Congratulations and good luck|||for better info.. you should not figure conception from the first day of your last cycle.. conception can happen from that date until 3-5 days before your missed period.. and sperm lives 5-8 days inside your body.


On that info and the ultrasound.. it gives an estimate.. as its too early to show signs of slow growth.. i wouldnt worry..





I assume you are HR because of your previous delivery.. are you considering VBAC?





Also below is a website for IUGR and i hope it helps..|||It is too early for the baby to be too small or too big. That is why the OB's use the early ultrasound to determine the due date instead of the date of your last period. Not all women have a perfect 28 day cycle so they don't know when ovulation occurred. My due date based on the ultrasound and date of last period were 4 days apart and the OB used the ultrasound date even though I knew when I ovulated which was 14 days after my last period.|||Exactly the same thing happened to me. By my LMP I am due December 12th, but the ultrasound says I'm due December 23rd. It just means you ovulated a little differently than they expected. The earlier the ultrasound, the more likely the due date is accurate. Will not impact anything in a negative way so don't worry about that.