Scroll way down to the bottom of the Hot One Hundred top breeders and youll eventually find the United States, hovering just at replacement rate with 2.07 births per woman.
Most of the time, no apparent cause for night leg cramps can be identified. In general, night leg cramps are likely to be related to muscle fatigue and nerve problems. The risk of having night leg cramps increases with age. Pregnant women also have a higher likelihood of having night leg cramps. Several conditions, such as kidney failure and diabetic nerve damage, are known to cause night leg cramps. But if you have one of these, you're most likely aware of it and have symptoms other than night leg cramps.
The cramp, or charley horse, is due to the muscle contracting (shortening and tightening) in a sudden and violent way. These nocturnal leg cramps usually occur in the calf muscle. But foot and leg cramps do happen at night also.Cramps in the thighs are less common. One main reason for the pain is because blood flow to the muscle is restricted.Waste products also build up within the muscle tissue. Dehydration. 2  Not staying hydrated with enough water during the day may be one of the big causes of leg cramps at night. 3  This is most likely due to fluid imbalances of electrolytes (mainly sodium, potassium, calcium, and magnesium).