Abstract
As shown in 79,000 girls and women participating in four different surveys, low body weight (≤47.2 kg) does not prevent the attainment of menarche, conception, or even repeated conceptions. Indeed, low body weight is especially common in early maturing girls and in Puerto Ricans and Mexican-Americans. From these data, the concept of a “critical weight” for menarche is difficult to substantiate, although low body weight does have nutritional implications and is the second most important factor in regulating fetal growth.