Ultrasound accuracy in dating pregnancy
"The accuracy of these ultrasounds depends on the skill of the technician and radiologist, the maternal habitus, and the position of the baby," explains Manglani.
"[A fetal well-being assessment] ultrasound looks for fetal movements, growth of the baby, position of the placenta, and the amount of amniotic fluid." An ultrasound can also act as a guide for your doctor during an amniocentesis, and can very accurately tell you if your baby is breech in the final weeks.She tells Romper that a first-trimester ultrasound can date a pregnancy within three to five days.By the second, accuracy drops to within "about a week." By the time your third trimester comes around, ultrasounds can't be counted on to provide you with an accurate or useful due date at all.If you see a heart beat flickering, you can certainly feel reassured."While these scans are very accurate, this does not guarantee the future viability of the pregnancy," notes Manglani.