Pregnancy After Miscarriage: Understanding Ultrasound Timing & Gestational Age

Question
Hello Rappaport,
  Well my name is kiran ,Iam 26 years old and 8 months married,I had a miscarriage 4 months before that is ,I HAD MY dns AT 20TH MAy ,this month sept i didnt had my periods that was dur on 15TH SEP,my last periods were at 15th of august and lasted for 7 days and finished at 21st aug,pregenancy test confirmed i am pregnent ,What i wanted to ask you is according to the doc he counting the days from 21st august and i am supposedly pregent for 6 weeks and she ask me to come for ultasound to hear the baby's heart at 8th,that will be 8th week  but my problem or question is i know that me and my husband were seperated from each other for the month of august i know that i concive at 1st sep because that was the date when i didnt use the rubber now if i count from then,than i shall be only 4 weeks pregenent and if i go for ultrasound then it will be only 5 weeks and baby's heart comes in between 4 or 8 weeks and my biggest problem is my own doc has gone for vaccation and she recoomended me to other doc for checkup,another question is my medince the name is Duphaston for 3 weeks that will be completed at 8th(the day for my ultrasound)but i know at this date 8 weeks are not completed so i dont want to go ,if i dont go then what should i do for my medince cause she said she will see the ultrasound then only will start the futhere treatment now you tell me what
should i do and i want to know about how these doc counts the weeks i know mine is 4 weeks,it couldbe futher late tooo then how the docs come to know?please do help me i am waiting for your reply
kiran

Answer
We count a pregnancy from the first day of your last period. YOur last period started on August 15. Therefore, you ovulated on August 29 and could only have conceived if you had sex on August 28,29,30,31, and September 1. You are now 6 weeks 4 days pregnant (we don't count from the day of conception, but only from the first day of your period). We usually cannot hear the baby's heartbeat until after 8 weeks (better at 9 weeks) from the first day of your last period. Therefore, make an appointment with your doctor for after October 10,  A sonogram will be able to "see" a fetus and a fetal hearbeat 6 weeks from the date of your last period. I would suggest that you complete the medicztion you are taking. You probably will not need any more medication. Don't worry.  Remember, the entire pregnancy is counted from the first day of your last period, not when conceived. A pregnancy is 40 weeks (from your last period until your due date), Your due date is May 22, 2006. Good Luck.