It's not recommended that you have laser treatment whilst you are pregnant, or in the first few months post natal.
Your prescription can fluctuate due to hormone changes and because of this it is not always possible to obtain an accurate prescription.
Six months after the birth is an appropriate time scale, though it is advisable to discuss this with your treating doctor at the time of your consultation.
History on past / previous prescriptions are very helpful as these will be used to gauge the stability of your prescription.
All eye surgical procedures carry a level of risk including not obtaining the desired outcome, through to varying levels of visual loss. Your eye surgeon will discuss the risks and benefits, including ones specific to your circumstances, at the time of your pre-operative consultation.