First trimester dating ultrasound
These sound waves send signals back to a machine that converts them into images of your baby.The standard ultrasound arms your doctor with valuable information.I'm in the uk and I think mine is out by 1-2 weeks I know when I ovulate etc so know when I conceived.I mentioned it in my 20 week scan and they say yeh it could be just over a week out but we don't bother changing the date because it doesn't make much difference!They are the most accurate way to date a healthy pregnancy.It may vary by machine but at my hospital they told me it is /-3 days for the early scan.I have had tiny baby's and my first three have been on my track with my lmp but this baby was measuring small at my dating ultrasound less then a week from my lmp and my ob changed my due date later saying he's a big baby.
The sound waves bounce off the fetus and send signals back to a machine that converts these reflections into a black and white image of your baby.
It will be hard to see much in this first snapshot, but a clearer photo will come around 13 weeks, which is the ideal time to share your exciting news.
Why it's important Your ob-gyn listens for your baby's heartbeat and estimates his age by measuring his length from head to bottom; the baby is tiny in the first trimester and is growing about a millimeter a day.
From this test, your doctor will be able to determine a more accurate due date and track milestones during your pregnancy.
Your ob-gyn will also rule out a tubal (ectopic) pregnancy, which is when the fetus grows in the fallopian tube instead of the uterus.
It allows him to monitor your baby's growth and track milestones, detect abnormalities, home in on your due date, determine whether you're carrying multiples, see the position of your placenta (important for delivery), and (a big one for parents-to-be! Another exam that utilizes ultrasound is Doppler fetal monitoring.