Egg production reduction

There can be lots of reasons for slow downs, molts, sickness, changes in their routine and the amount of light (time wise) they get per day. My girls are just getting through a molt and had slowed down for that, now the hours of daylight are getting short. Yours are a bit young for molt. If they havent been sick and there haven't been any other significant changes its most likely because the days are getting shorter and shorter. You can put a light on in the coop for a couple of hours at night to see if it helps. Some people would rather naturally let their ladies slow down during the winter and others put a light on for a few hours which helps with egg production.