Antepartum fetal testing can be performed after 39 weeks in patients with sub-optimal dating due to concerns for post-term pregnancy . Check with your ultrasound clinic for any preparation you need to do prior to the scan. The American College of Obstetricians and Gynecologists.
It will not harm you or your baby. Ultrasound examinations from 12 to 22 weeks are regarded as being within 10 days of accuracy or up to 10 days earlier or 10 days later than the woman's calculated due date. The scan or my dates - which should I believe?