You may wonder, “Can a scan lie about weeks of pregnancy?” The good news is that most scans will show that your baby is developing as it should, so the answer is no. However, if the sonographer finds anything unusual, they will let you know. Regardless of the answer, you should always keep your ultrasound report with your maternity notes.
A typical ultrasound scan is used to check the baby’s development and to identify its sex. However, the baby’s position and the mother’s BMI can affect the results. For these reasons, some scans are unable to tell the sex of the baby. In these cases, some hospitals have a policy of not telling the sex to prevent mistakes.
Moreover, obesity can reduce the accuracy of a scan by 50%. This is because the high-frequency soundwaves that are used during an ultrasound take longer to travel through increased body tissue. Also, the distance between the ultrasound transducer and the uterus affects the clarity of the image.
However, ultrasounds conducted before twenty-two weeks are more reliable in estimating the due date of a pregnancy than scans done after this point. The results of scans taken after this point can be off by one or two weeks. If you have doubts about the accuracy of your ultrasound, talk to your doctor or midwife.