I always joked that I didn't want to know my due date. Those dates seemed to come and go for my friends and which made them very frustrated! I didn't want to be focused on a date. I am also the odd one that didn't find out what we were having.
But seriously, according to the resources below, a due date is only an estimate of when you will deliver. Also, the fundal height is used to get a rough idea of how far along you are.
Congratulations! I am sorry this has you concerned but it's difficult to guess what they could be calling about. You may want to post on our 1st Trimester Community to connect with other moms-to-be in your same stage.
Here are a couple of resources that may be also be helpful -
The opinions expressed in WebMD Communities are solely those of the User, who may or may not have medical or scientific training. These opinions do not represent the opinions of WebMD. Communities are not reviewed by a WebMD physician or any member of the WebMD editorial staff for accuracy, balance, objectivity, or any other reason except for compliance with our Terms and Conditions. Some of these opinions may contain information about treatments or uses of drug products that have not been approved by the U.S. Food and Drug Administration. WebMD does not endorse any specific product, service or treatment.
Do not consider Communities as medical advice. Never delay or disregard seeking professional medical advice from your doctor or other qualified healthcare provider because of something you have read on WebMD. You should always speak with your doctor before you start, stop, or change any prescribed part of your care plan or treatment. WebMD understands that reading individual, real-life experiences can be a helpful resource, but it is never a substitute for professional medical advice, diagnosis, or treatment from a qualified health care provider. If you think you may have a medical emergency, call your doctor or dial 911 immediately.