Confused About Dating of Pregnancy

Cynthia Flynn's picture


Dear Midwife,
Boy where to start. I had a miscarriage on may 25th of 2008, this would have been my 2nd child. I found out I was pregnant around mid to late September, I had no idea. I know I didn't have intercourse until about the 16th of June at the earliest.

From ultrasounds done they are telling me my due date is the 24th of next month and I will be lucky if he is in the lower range of 9 lbs.

Now I bled after the miscarriage for probably close to two weeks. I found a calculator online that you put the due date in and it tells you the date you likely conceived. This calculator told me right about June 3rd which is impossible unless I am the virgin mary...and I don't think I am.

The midwives just wont seem to listen to me. I don't know what to do and don't know where else to turn anymore, the date is getting closer and closer and I just want to be sure that the date they are giving me will be ok for him.


First, I am so sorry for your loss, and also want to congratulate you on your successful pregnancy!

If you are certain of the first day you had intercourse, then obviously conception could not have occurred sooner. End of story. With a conception date of June 16, the earliest your due date could be is March 9, and it would be ok for your baby to be born anywhere from Feb 16 to March 23. If you didn't find out that you were pregnant until late Sept, you were already at least 15 weeks pregnant (maybe more) and if the midwives are using an ultrasound from late Sept/early Oct to date the pregnancy, the dating can be off by 10-14 days (or even a little more), depending on the skill of the ultrasonographer. If you are having a big baby, we would expect the "due date" as calculated by an ultrasound to be earlier than the real due date.

If you were my client, I would be making sure that you passed your sugar test; I would be watching your diet like a hawk, and maybe even putting you on a diabetic-type diet even if you did pass your test; and I would not induce you (if you didn't want to be induced) until about mid-March. However, my advice is based only on what you are telling me. Obviously, I have never even met you, I don't have your full history (including the weight of your first child, your weight gain since entering care, etc etc), so there may be important factors that I am not taking into consideration. I do wish you a wonderful labor and delivery of a healthy baby. Good luck!

--Cynthia, CNM. PhD.