It happens with so many couples after the birth of the child as for women sex is not the priority as they have to put too much effort into kid so give her enough time to focus on the sex life. One thing is good that she is aware of your situation so with time she will start putting effort to bring back your intense sex life.
What you need to do here is keep raising your concerns and desire whenever you get a chance and you find her in a good mood but make sure that you do not accuse her for anything otherwise she would get defensive. Have a healthy conversation with her and let her know your desire but at the same time show the patience to give her time. It is the matter of the priority and nothing else.
Help her in household works, communicate with her in a healthy manner, ask her what she needs and how she feels, show your affection and patience, do not make her feel that you want sex all the time, spend quality time with her and cuddle with her, take care of the baby and play the role of responsible husband and father at the same time, do not expect too much things from her as she might not have enough energy to meet your demands. I am sure with time you both will start having sex as you used to.
I do not think it would be appropriate to blame her as her situation does not allow her to focus on the sex at this time. Every couple faces such kind of time in their married life sooner or later but that does not mean that one has to lose the hope to get better.