Sonogram dating for due date
Even when the last period is known, ultrasound is reassuring to demonstrate adequate growth, especially when there’s a risk of delayed growth, as in hypertension or smoking, or if there’s the risk of exaggerated growth, as in gestational diabetes.It is not uncommon for babies that are labeled “Large for Gestational Age (LGA)” and “Intra Uterine Growth Restriction (IUGR)” to have monthly or even weekly ultrasounds during the pregnancy.When an ultrasound is performed, measurements of the head, abdomen, thigh, and amount of amniotic fluid are done.
The scan can check that your baby's heart is beating nicely and that he's developing normally.
The software has certain measurement scales based on data from large populations, and your baby’s measurements are put into this scale.
In other words, by comparing your baby’s measurements to the data from this large collection of measurements, the ultrasound can then tell how far along your baby is.
Pregnancy is dated from the first day of the last menstrual period, so at four weeks, a woman is just due for a menstrual period.
At 4.5 to 5 weeks, a gestational sac may be seen in the uterus using transvaginal ultrasound, Joseph Woo, M.