If you are worrying your chickens would stop laying eggs during winter, you can do these essential things to help them maintain their body heat.
Remember that chickens are tough in cold. They usually fluff up their feathers to trap in the heat and stay warm. They do not need a heated coop but need dry shelter. Before winter comes, inspect their coops and do needed repairs to make them safe from predators.
Good ventilation is also needed. Closing their coops tightly would build-up ammonia gases and could affect their respiratory system.
Also put straws in their coop to maintain their feet warm. Replace it from time to time.
As hens rely on light for egg production, there is a tendency that it will slow down as they need 14 or more hours of daylight to lay well. Night is longer during winter so consider putting a light bulb in their nesting area.
Fresh water is also necessary. Always provide and replace it several times a day as it could freeze quickly. If possible, invest on a heated water bowl to make their water stay warm throughout the day.
Lastly, always make sure that you provide them enough feed to keep their body heat up. It is also advisable to feed them in the evening as it would help them stay warm as their bodies digest the food.