goofie,
hehe no prob lah, glad to help. but my ans are based on my own experience and beliefs lah. so other ppl might advise u differently. u use yr own discretion hor.
down syndrome test - yes i did the test for both #1 and #2. the test consist of a BT and a NT scan. u can choose to do BT only or scan only or both. then a risk assessment will be computed based on the results. if u do both BT and scan is supposed to be the most accurate. but this only give u the risk of bb having down syndrome, is not a definitive yes/no. only amnio can give tat but amnio has it's own set of risks so usually dr ask u to do the BT/scan first. BT/scan usually done at 12-14wks.
stretch mark cream - hmmm this is quite subjective, u need to try a few cos some are quite light, some are quite rich and some may cos itch if yr skin is sensitive. so a bit of trial and error. the more common brands out there are Palmers, Elancyl and some ladies are using olive oil too
http://www.olive.sg/main10.php
stretching exercise - i think light stretching for the arms, calves are ok but try to avoid stretching the stomach and back area. after 1st tri u can consider pre-natal yoga lor to relieve all the tightness.
eating - is ok to eat now lah, just follow yr body cues, if u're hungry eat cos there will be times when u really dun feel like eating. just pick healthy food like low fat milk, fruits etc dun overload on junk food lah (potato chips, chocolate etc). now is not the time to worry abt weight gain yet.
dha - no need to start yet, usually start around 5th mth onwards cos we take dha mainly for brain development and that's when bb brain really starts to develop. before that is basic organ development only. there are a few recommended brands out there too, otherwise u can also ask yr dr to prescribe or recommend. it's in softgel capsule form, taken the same way as vitamins
