There are absolutely no contraindications to undergoing the procedure during menstruation.
The period required for vision to stabilise following laser vision correction may last up to 6 months. During this time there should be no hormonal fluctuations, including the ones normally appearing during pregnancy. That is why pregnancy should be postponed until the 6-month stabilisation period is over.
During the convalescence time after the procedure special attention should be paid to proper eye lubrication. When you travel by plane, your eyes are exposed to extremely dry air. In order to reduce the negative effect of plane conditions on your eyes, you should refrain from flying for the first three days after the surgery and apply preservative-free moisturising eye drops every hour (the drops are part of a medicine kit you will receive prior to laser vision correction, which is included in the cost of the procedure).