by 20wks many women find they are feeling pretty good, morning sickness tends to lessen along with the fatigue that's so common early on. gender is typically able to be seen on an ultrasound, most hospitals automatically take you to labor & delivery if you go in to be seen in the er or urgent care. at this point a loss would be considered a stillbirth rather than a miscarriage (I believe) & should you go into premature labor most hospitals will try to intervene & stop labor (earlier than 20wks they rarely do). Should labor begin & not be able to be stopped, your baby will officially have some chance (though small) of survival with help from steroids to help force the lungs to mature & strengthen. You can also exppect to have an ultrasound where they check that you babies organs are developing correctly & that their kidneys are functioning. I believe there are some routine tests that are done around 20wks as well (lab work).
congrats on hitting the half way point!!