Start and end dates for N previous months

Program.cs

using System;
using System.Collections.Generic;

namespace ConsoleApp1
{
    class Program
    {

        internal class DateRange
        {
            public DateTime StartDate { get; set; }
            public DateTime EndDate { get; set; }
        }
        static void Main(string[] args)
        {
            var list_of_dates = new List<DateRange>();
            const int MAX_PREVIOUS_MONTHS = 18;

            var today = DateTime.UtcNow;
            var current_month_first_day = new DateTime(today.Year, today.Month, 1);

            list_of_dates.Add(new DateRange { StartDate = current_month_first_day, EndDate = today });

            int counter = 0;
            while (counter < MAX_PREVIOUS_MONTHS)
            {
                var last_month_last_day = current_month_first_day.AddDays(-1);
                var last_month_first_day = new DateTime(last_month_last_day.Year, last_month_last_day.Month, 1);

                list_of_dates.Add(new DateRange { StartDate = last_month_first_day, EndDate = last_month_last_day });

                current_month_first_day = last_month_first_day;
                counter++;
            }
            
            PrintDates(list_of_dates);           
            Console.ReadLine();

        }

        private static void PrintDates(List<DateRange> list_of_dates)
        {
            foreach (var date in list_of_dates)
                Console.WriteLine($"from = {date.StartDate} to = {date.EndDate}");
        }
    }
}