Is Low Birth Weight Dangerous? 7 Factors Affecting the Weight of the Child

Immediately after birth, the child is weighed and their height is measured. During the next months of life, a small being will repeatedly undergo this procedure because weight and height are the main indicators by which pediatricians assess physical development. Babies are born with different body weights. There are really big babies and there are babies with low birth weight. What does the weight of the baby depend on?

Norms of Weight for the Newborns

The question of the weight of the newborn is of interest to all future mothers. As a rule, a pregnant woman begins to think about this topic in the third trimester of pregnancy. What is the normal weight of a newborn?

In general, the weight from 5.7 to 10 lb. is considered to be normal. That is, the weight of 5.7 lb. is quite normal if the fetal age has reached 37 weeks. Such a child can develop normally, does not require special care and maintenance of the right temperature. Also, there is no need to feed the baby too much, this can only increase regurgitation.

Weight loss in the first days of life is also normal. A child can lose up to 8% of his weight. The newborn’s body adapts to the surrounding environment, excess fluid is excreted. Also during the first 2-3 days, the baby only learns to take breasts and develop sucking skills. On day 4, the body weight of the newborn should begin to increase, on average by 0.7 oz. per day.

Even if a child was born with a weight of 5.7 lb., and then has lost 5 oz., then the weight will still be considered normal. It is not low birth weight. The specialists in the maternity hospital watch over the weight loss attentively during the first days.


Infants Birth Weight

  • 3.3-5.5 lb. – low birth weight
  • 2.2-3.3 lb. – very low birth weight or prematur
  • 1.7-2.2 lb. (gestation period less than 29 weeks) – children with extremely low weight
  • less than 1.7 lb. (term of the gestation below 26 weeks) – children with ultra-extremely low weight

Factors Affecting the Weight of the Child

Why does one mother give birth to a 10-pound child, and the baby of another one weighs less than 6 lb.? What does such a big difference in the weight of newborns depend on?


As a rule, big parents tend to have bigger children. It rarely happens that a mother with a height of 5.9 feet gives birth to a child who is less than 6.6 pounds (provided that the baby’s gestational age is not less than 37 weeks). 

Gestational Age

Premature babies are born with less weight than those born on time. Also, full-term children born in the 37th week are significantly smaller than those born in the 42nd week.

Multiple Pregnancy

If a woman expects two or three babies, it is worthwhile to prepare for the fact that the children will be small. Also, multiple pregnancies rarely last 37 weeks or more. In most cases, birth occurs in the 34th-36th week. As a result, the weight of newborns may not even exceed 4.5 lb.

Gender of the Newborn

According to the statistics, newborn boys have a heavier weight. Girls are usually smaller.

The Number of Pregnancies

Most often, if a woman already has a child, then each subsequent child is heavier than the previous one.

Mother’s Health

If a mother has health problems or if the pregnancy has been complicated, the child can be born small. Chronic diseases must be cured before the onset of pregnancy. Because of certain diseases, such as diabetes, a newborn can be overweight.

The Lifestyle of a Pregnant Woman

If a future mother does not eat well, doesn’t abstain from alcohol or cigarettes, it will not only affect the health of the newborn but also cause a deficit in weight. If a pregnant woman is eating a lot of fast food, smoked or salty food, then this can lead to overweight in the newborn. A too big fetus can be the cause of a difficult birth.

As it can be seen, the weight of the newborn depends on a lot of factors. Some of these factors a mother can fix. A healthy lifestyle, proper nutrition, and pregnancy planning can reduce the risk of low birth weight.

Heavy and Light Weight of Newborns

Children whose body weight is less than 5.7 lb. are considered small. In most cases, the cause is prematurity, multiple pregnancies, or a mother’s disease. If the low birth weight is caused by multiple pregnancies, then there is no need to worry. Such children by 1-1,5 years catch up with their peers and do not differ from them at all.

If the cause is prematurity, then the main task is to develop immature systems of the body rather than to gain weight. Such children require special care. They should stay in the hospital until the moment when their body begins to function independently and the bodyweight reaches the necessary minimum.


If a woman has problems with her heart or endocrine system or suffers from hypertension, then the child can be born underweight. At the same time, the height of the newborn may be normal. Then the child is diagnosed with Hypotrophy. Doctors prescribe a special diet for such children. The child’s low birth weight is a problem only at the beginning of their life. With the correct approach, by the age of 1.5 years, these children don’t differ from their peers.

If a newborn weighs more than 10 lb., then they are considered heavy. If the reason is the disposition toward it, you don’t have to worry. But if the heavyweight is not a hereditary disposition, it is desirable to consult an endocrinologist.

Whatever the weight of the newborn is, the main thing is that the child is healthy, happy, and desired. Children with low birth weight can be much healthier and have better physical development than their peers in the future.

Causes of Low Birth Weight: What Causes Intrauterine Growth Retardation?

Unfortunately, no one knows the exact answer. Although, there are some factors that are associated with the lack of functioning of the placenta and the low birth weight of the child. One of these factors is heredity. So, small women tend to give birth to small children. In addition, there are differences among racial and ethnic groups.

Also, the first child is usually smaller than their brothers and sisters. This is probably because the uterine blood vessels are more developed after the first pregnancy and more effectively nourish the next children. But in this case, we are talking about a child who has a low birth weight for natural reasons and not because of violations.

Some children do not receive sufficient development in the uterus of women under the age of eighteen or older than thirty-five. This may be due to poor nutrition or due to the fact that a woman may have health problems (for example, high blood pressure) affecting the effectiveness of the blood vessels of the placenta.

Key Factors

However, the key factor is, most likely, the nutrition that the child receives in the uterus. But although it is very important to have a balanced diet that includes all the main groups of nutrients, i.e. protein foods, dairy products, fruits, and vegetables, the mother’s diet plays a very small role in the development of intrauterine growth retardation of the child.

Any disease that affects the transportation of blood oxygen and nutrients to the baby can interfere with their development. The most common causes are hypertension and certain kidney diseases. One of the frequent causes of delayed development which can be eliminated is smoking. A woman who smokes a lot during pregnancy can give birth to a child weighing 5.3 oz. below the norm. The more the mother smokes, the less oxygen the child receives and the less he/she grows.

In some cases, the causes of developmental delay are associated more with the fetus than with the health of the mother. Thus, twins compete for the right to receive oxygen and nutrients. As a result, sometimes one of the babies gets much more than the other. This can cause complications for both children.

In very rare cases, some infectious diseases can be the cause of intrauterine growth retardation.

What is the Danger of such a Violation?

The birth weight of a child affects their chances of survival, their well-being in the first few days of life, and their physical and intellectual development in the future. In general, the smaller the child is, the more difficulties they may face in childhood, and perhaps even in adulthood. Nevertheless, most children with low birth weight or born premature who receive appropriate care during pregnancy, childbirth, and during the first few weeks of life, later often catch up with the overall physical development of their peers. In addition, their mental development can be normal, and they don’t have any deviations in behavior or physical development.


However, sometimes a child who has not received sufficient development in the uterus can later lag behind in physical development. In some cases, such children also have mental development disorders.

Low Birth Weight and Health in Future

Children who were born with very low birth weight later in life have the risk of developing depression, attention deficit and hyperactivity disorder, and other mental illnesses. The risk is higher compared to children who were born with normal weight.

Numerous scientific studies carried out earlier have established that children born with low birth weight are at higher risk of future health problems, including obesity, hypertension, diabetes, and heart disease.

Low birth weight can subsequently lead to the development of various diseases – from problems with breathing to diabetes of the second type.

At the same time, in the future, the risk of alcohol and other psychoactive substances addiction is much smaller in children with low birth weight. Dependence on alcohol and drugs in them was observed almost three times less often than in people with normal birth weight.

The birth of an underweight child is a serious problem. This is much more serious than the birth of a heavy child. Weight deficiency occurs when the child receives not enough necessary substances in the uterus. Accordingly, the development of all organs and tissues occurs in unfavorable conditions. It is accompanied by dystrophic changes and impaired functions of the organs. Therefore, the problem should be considered more broadly than simply “weight gain”.

Children with low birth weight are more prone to metabolic disorders, and at an older age are more likely to be overweight. In adulthood, such children may have the problem of obesity, hypertension, and type II diabetes mellitus. This does not mean that it is necessary to “limit the baby in the diet”. Just remember that the food should be balanced and quality, containing all the necessary nutrients, vitamins, and trace elements. Also, the diet should be consulted with the pediatrician.

How to Detect the Delayed Development of the Fetus?

In the first twenty weeks of pregnancy, a suspicion of a delay in fetal development can arise if, during palpation, it becomes clear that the size of the uterus does not correspond with the gestational age. In the future, this may be accompanied by an insufficient increase in the weight of the mother, and sometimes even weight loss. The diagnosis is refined by fetal measurements based on an ultrasound. Such a diagnosis requires several studies.