Unfortunately, you can't change the position of your placenta even if you wish to, but it's common for the placenta to adjust and grow as the uterus grows. If you've got a low-lying placenta in the second trimester, your placenta could grow upwards, pulling you away from a risky birth. But it could also grow downwards, which isn't in your hands.  An ultrasound done at 32 weeks will help your doctor consider options for the safe birth of your baby, in case it's a risky one.