Fetal Movement at 21 Weeks: What's Normal & When to Worry

Question
At 21 weeks, I have been enjoying the baby's movements for a couple of weeks now. My 20 week ultrasound was normal.  However all today morning, normally when the baby is actively kicking, I haven't felt anything.  I also don't remember much from last night, since I was fast asleep.

Should I be worried?  How do I monitor the baby's movements?  I always try to sleep on my left side, however I might have been on my back for a while before I realised it and turned.  Does this affect the baby?

Also, I have been wearing some elasticated pants which rest right on my belly button, because they are very comfortable. Could they pose a problem by pressing down when I am sitting, etc?

One more question, I sneeze too loudly, almost violently.  Is that harmful for the baby in any way?

Thank you for all your answers, Dr. Rappaport.

Answer
Neither the clothes you wear, the position you sleep in, or the volume of your sneeze will cause any danger to the baby. We would prefer you to sleep on your left side in order to increase perfusion to the uterus, but no harm will come to the baby if you don't. Normally, kicking starts around 22 weeks gestation (some woman notice kicking a week earlier). There are sleep cycles and wake cycles for the baby and you do not always feel kicking. After 22 weeks, you should feel fetal movement (hiccups, rolls, turns, kicks, gurgling, etc). If you do not feel any movement at all when you had previously felt movement, youo should contact your doctor and get a non stress  test to see if the baby is O.K. We also instruct patiients to perform "kick counts" where you see how long it takes to feel 10 fetal movements (of any kind). That should be your standard. If the kick counts appear abnormal, contact your doctor.