Girls, who has this, when lying on their left side, there is strong lo…

Girls, who has this, when lying on their left side, there is strong load on the heart, as if something presses on it, and pressure drops immediately, but on the right side it's easier, but I know that it's preferable to lie on the left side. Today at Doppler ultrasound said the sonographer that the baby has a little bit of oxygen deficiency, and they told me to lie on the left side, and I feel bad when I lie like that, I told the doctor, she didn't answer anything, what would you recommend? I'm worried about the baby not having hypoxia ?