Ob-Gyn questions? Ask a gynecologist online.
We can't do anything at the stage. The yolk sac is the first anatomic structure to appear within the gestational sac. It can be noted initially at the beginning of the 5th week of gestation (MSD approximately 5 mm), although it may not appear until the MSD approaches 8 mm. MSD: mean sac diameter. You may do normal activity. Laying down doesn't help.