<font color="0000ff">Shir Shir</font> - RE: U/S, abit controversial leh, it depends on one's belief I guess. For instance, my neighbour; an Indian expat - her Sister is a Gynae & she doesnt screen herself until the 3rd month (2nd T) because they think U/S makes a pregnancy unstable (and increases the chances of M/S). For me, I dont really buy this part because if that's really the case, it should be an 'international rule', this is how I deduce it lah.
I've read from pregnancy books & such, even from BabyCenter app - it seemed like the encouraged time frame to visit a gynae & U/S is on 12w onwards. I believed these are USA sources, which my friend in USA also freaked out abit when I told her I visit the gynae once every 3 weeks (I think their "normal" is 4-6 weeks until last T).
There are sources that claims that even weekly U/S wouldnt affect the fetus, and there are some that cited per U/S shouldnt last any longer than 30mins because it would be straining for the fetus. How it works is that the waves are sent to the BB and the signal is bounced back/off from the BB in order to deliver the image to you, although it is said that the waves signal are very low but some draw a parellel to why preggers cannot do X-ray because of the harmful waves (but I also think X-ray de waves are so much more stronger, so it's like not a fair comparison) so... to me, this debate is not going to end, hahahahah! Oh, before I forget, if I remember correctly the waves sent to listen to your BB's heatbeat are stronger - I think I read the above earlier somewhere here in this thread too because I listened to my BB heartbeat on W7 but read from some MTB that their gynae didnt encourage it until the later weeks cause it's not safe, oh geez!
Anyway.. I personally think it is fine, unless the Gynae said otherwise lah, like for instance, on that visit whereby I had OSCAR screening earlier on, then she advised me not to screen again... My visits are once every 3weeks like you too, I think I'm comfortable at that period difference, and also, aside OSCAR, most of the U/S done during visits are like 10-15mins, sometimes even lesser only so it shouldnt be THAT bad loh...
My 2 cents worth lah...