Hi mga momsh,Bakit po kaya binabago bago ng ob ang prenatal vits. ? 31 weeks preggy

After ko po maconsume ,pinapalitan na ulit ng new brand , from hemarate at obimin nging hemrate at mosvit then sorbifer at obnate iq then etong last check up ko magiging prenat at calvi plus .Curious lng po as a first time mom, kasi ung ksbayan ko ngstay sa iisang vits. Reseta sknya which is hemrate ,calciumade at mosvit . I also finished taking calciumade. Thank you sa response