Hi, Your history suggests that you may have either miscalculated your dates or you do not have regular 28-30 day cycles. This is in accordance with the sonogram reports done at different centers. There can be slight variation in the dates as the size of the sac is very small and estimations may have slight differences when done by two different persons. So, there is no need for worry with the slight difference in the gestational age from the two reports. What should be noted is the viability of the pregnancy. Your doctor may have wanted to assess the pregnancy and the progress and thus asked for serum beta-hCG titres as doubling titres once every 2-3 days is seen in a normal pregnancy at this stage. Please avoid anxiety, take bed rest, avoid intercourse and follow your doctor s instructions. Good luck.