Vitamin B12 injections

My primary care doctor drew blood last week and called me with results. She said my blood levels are down, and I’m low on vitamin d which are causing my anemia issues to show in blood work again! I called my OB-Gyn today and they said I need to start taking Vitamin D pills, and getting Vitamin B12 injections on top of taking my prenatal vitamins.

Has anyone gotten the Vitamin B12 injections during their pregnancy? If so, where do they give you the injection, does it hurt, how long does it take, and do you need to get the injections until you give birth?