Besides knowing that all fingers and toes are exactly where they need to be, length and weight of a newborn are the first information you will get after the birth. These measures are important because by comparing them to the charts we can see if the baby is normal and everything is ok with their health.
In the first year of the life many children grow very fast and some can even triple their weight at birth. This is considered to be normal and some babies that seem to be growing at a slower pace are sometimes checked for medical problems.
Several factors determine the weight of a child at birth, including duration of the pregnancy, rate of fetal growth, gender and health of the newborn, birth order, size of the parents and also some birth factors. Race and ethnicity of the mother, as well as her nutrition and medical risks during this or some previous pregnancies are also factors to contribute to average birth weight.
Most babies born in the United States weight about 3.5kg (or 7pounds 11 ounces) at the time of birth. Statistic data reveal that babies born after full pregnancy (40 weeks) are usually about 2.750 to 4.250grams. Situation is similar in other parts of the so-called developed world. If a pregnant woman is getting proper nutrition and there is modern medicine available, babies are normally born with 2.7 to 4.6kg. Comparing the weight of the babies for the last several decades, we can conclude that children tend to have slightly more weight at birth than 20 years ago. In the 90s, most kids were about 3.372kg, while now children usually weight somewhere around 3.434kg at birth.
There is no way to tell who is heavier at birth, boys or girls, because both genders can be of same weight. However, some claim that boys often have some 100g more than girls.
There are also children born before the end of 40 weeks. These premature babies are born with less than average weight and length and they are usually kept in NICU for several days after the birth. Some 5% of newborns have less than 2.5kg and even less than 0.08% have extremely low birth weight, less than 1.5kg.
Twins Birth Weight
Above mentioned statistic data about weight at birth is about giving birth to one child. It is different for multiple pregnancies. Many times, twins are born in 37th week of pregnancy and some triplets at 34th weeks. As the matter of fact, about half of multiple pregnancies gave birth to premature babies so this not unusual.
Multiple born kids are in many cases born with low birth weight and there might be significant difference in the weight of twin babies, even up to 3 pounds.