Hi. my girlfriend and i are planning our first ski trip in the beginning of march. she want to know how she can postpone her period without the pills?

Besides getting a severe illness, rapid and significant weight loss, or pregnancy, it is not easy to postpone a menstrual cycle without chemical intervention, or in this case “the pill“ as you suggested. Also it depends on how far away is the menstrual cycle is to start. “Normally” it is virtually impossible to postpone it with less than 3 to 5 days away. Best of luck and have fun on your trip!