Understanding Ultrasound Dating & Calculating Your Due Date

Question
QUESTION: Dear Dr., my LMP was on 13th June 2010. However the pregnancy was detected only in August 11th 2010 which showed that I was 6 weeks pregnant. Now my due date is given as 10 April 2011. Can an ultrasound predict the accurate due date especially with irregular cycles ? I had done ultrasound in July which showed no gestational sac. According to my doctor's fundal measurement I am 32 weeks pregnant while the ultrasound showed 33-34 weeks. If I take the LMP, what should actually be my due date ? I conceived taking siphene 100 mg. Thanks for your time and advice in advance

ANSWER: Dear Salome

It is quite normal to have a difference of 1-2 weeks betwwen ultrasound dating and dating according to your LMP.
However; if you are sure of the date of your LMP, then calculation should be mase according to it and NOT ultrasound. If your cycle is every 28 days, then your expected date should be 20 March 2011 with a margin of 2 weeks more that is till 3 april or less back to 7 March. These calculations are only valid if your cycle comes every 28 days.

Good Luck



---------- FOLLOW-UP ----------

QUESTION: Dear Dr., am now in my 35th week of pregnancy and experiencing extreme pain and pressure in my lower abdomen till the pubic bone. My lower back pains too. When I sit the pain starts from my hips right till my knees. Does this mean that the baby has dropped into the pelvis ? At which week does the baby drop into the pelvis ? Is it true that the baby can be born anytime after the 36th week ?

Answer
Dear salome

First, I would advise you to seek examination as the pain you described may be an early sign to have a preterm labor. It does not mean that the baby has moved down to the pelvis. This down movement is known medically as engagement and it occurs between 37-40 weeks if this is your first pregnancy but may be delayed till the time of labor and delivery itself if you had an earlier term pregnancy. As for your last question, yes the baby can be delivered, although unusual, at any time after 37 weeks but this will be preceeded by labor pains for hours and the passage of the mucus plug out of your vagina.

Good Luck