whether cortisone efffects future pregnancy?

Iam suffering from hip n back pain for almost 2years.
Physiotherapy also didnt make any difference to the pain releif.
Am 25 years old female and am afraid to take the injection of cortisone as whether it will effect my pregnancy(if we are planning to b pregnant in next few months).
according to my Dr only cortisone can help me to get relief from this severe pain.
Am in a dilemma whether to take it or not,as whether it will effedt future pregnancy or not