QuestionOkay, I conceived some time between January 5-8, 2009. It has been confirmed that I am pregnant. However, it seems that the doctor is putting me further along than I am and it is causing problems with me and the child's father. I know for a fact that I had unprotected sex only during January 5-8th. No time before or even after. I missed my January cycle and went to the doctor the 1st week of February and the doctor said that I am pregnant. On April 29th the doctor stated that I was at 18 weeks and my due date is Sept. 30. Is he correct? Or would I be less than that, I'm thinking like 4 months a week & 1 day and my due date actually being on Oct. 8, 2009 or later?
AnswerDear Pamela,
Actually - both you and your doctor are exactly right. :-) The due date of Sept. 30 and the ultrasound dating of 18 weeks on 4/29 both indicate an estimated conception date of 1/7.
Here may be the source of your confusion... The calculation of gestational age, or pregnancy dating, is not actually based on the conception date. It is based on the LMP date. Always. Even if the LMP date is not known and even if the dating is determined via ultrasound. The ultrasound will automatically calculate the gestational age determined by the measurements of the fetus or gestational sac, etc,..., but that is all based on norms for gestational age calculated from LMP. The actual "full-term" confinement of pregnancy is 40 weeks from LMP to delivery. It is assumed that conception takes place two weeks after the LMP date because most menstrual cycles last 28 days, with ovulation occurring on/about CD 14-15. I know... this is very confusing for women, but that is just how it is.
I hope this has helped you and answered your question. I wish you well.
Brenda
