Folic acid and vitamin D are considered vital by the NHS. Folic acid is essential now, to ensure the baby’s neural system has the best chance of developing without problems, and I think that vitamin D is important as soon as the skeleton starts to develop properly, to aid calcium uptake, or something. I took a prenatal every day I was confident I could get it down, and just folic acid and vitamin D on the other days.
I can’t recommend a brand, I’m afraid. I have read some stuff which suggests that I might not be good at converting folic acid to something the body uses readily, so I use the methylated version, which is ready for the body to use. As a result, the prenatals I ended up buying are absolutely horrendous - large, and bad-smelling. Before that, I just used the ones from Wilkinson’s because they were cheapest. They contain everything they are supposed to contain and don’t smell horrendous!
Can you have an appointment with a GP or asthma nurse about your asthma with respect to pregnancy? I know that some people use both steroid and reliever inhalers in pregnancy, but you need actual medical advice in your situation. A telephone consultation might do the trick.
The yummiest things to stick in a smoothie are strawberries, almond milk, dates, apple, banana, pineapple, some tasty seeds.