Nipples get hard in the cold in order to preserve heat. If a nipple is exposed to the cold the automatically contracts, and this in turn causes the nipple to become smaller, wrinkled and hard. The reason this happens is to reduce the amount of surface area on the nipple that is exposed to the cold. As a result of this the body losses less heat and the amount of energy required sustain homeostasis (keeping normal body temperature) is decreased. Decreasing surface area of the skin is the ultimate reason why nipples get hard when it is cold.
No. Nipples will harden as a reflex when they are stimulated or cold.
Because the temperature is cold.
The same reason you get gousebumps!
mainly because your cold.
Becuz were cold!! =p
Everyone is different. When you are young your nipples may be hard a lot of the time. As you get older your nipples tend to become hard only when you are cold, wet or sexually aroused.
temperature - cold makes this happen
When it's cold or they're turned on.
Ice...or cold objects
They get Cold and harden.
so there nipples go hard
nipples generally get hard for 2 reasons 1. your cold 2. your horny this has nothing to do with pregnancy and is completely normal