It is not clear to me as to why you were taking Optisulin, a multi-ingredient cocktail of vitamin B complex factors, vitamin C, calcium, chromium etc. unless you had documented deficiency of all these agents at the same time which is most unlikely. Taking supplements without any need can lead to adverse effects. For example excessive dose of calcium can result in kidney stones.
All medicines except those specifically required for pregnancy should be avoided. You actual need is folic acid (brand name: Folet, one daily till labour) or along with iron, if you are anaemic (brand name: Globac Z Softules, one daily till labour).