Baby Sizes by Weight

Comparing baby sizes by weight can be difficult because there are several variations. However, the following information can be used as a general guide.

Average Weight of Infants

A newborn can weigh up to 7 lbs and be up to 17″ long. Babies up to three months can weigh up to 7-12 lbs. They can reach lengths of 17-23″. For three to six months the weight can be 12-17 lbs and be as long as 23-27″. Babies six to twelve months are 17-22 lbs and are 27-29″ long. When a baby is between 12 to 18 months, their weight will range from 22-27 lbs. They are usually 29-31″ long. When they reach 18 to 24 months, the average weight is 27-30 lbs. The average length is 31-33″.

Baby Sizes by Weight: Vital Factors

The weight of a baby will be influenced by their environment. The biggest contributing factor is the health status of the mother. A mother that takes nutritious meals and under proper care helps babies growth wise. Gestational age is also a factor.

For example, babies born at 41 weeks will weigh different from those born at 37 weeks. Pregnancy length is also a contributing factor. Babies born early usually weigh under the average. Full term babies typically weigh around the average. Larger babies are those born after their due date. The smallest are those born prematurely.

Other Influencing Factors

Genetics can play a role; physically large parents are likely to have babies large than the average. Similarly, parents who are petite may end up with babies weighing below average. Studies also show that multiple births are smaller compared to the average. The reason is they have to share space in the uterus with others. Multiple births are often premature. As stated earlier, premature babies are often lighter.

In some cases, firstborns are lighter than their siblings, although this is not always the case. Baby boys weigh a little more than baby girls. But the difference is usually very little. The difference only becomes apparent when they grow.

Why Some Babies are Underweight

Many factors can be cited, but the mother’s health status is the most significant element. Some of the reasons include smoking during pregnancy, taking alcohol, high blood pressure, heart problems or substance abuse. These have detrimental effects on babies.

There are several issues that come into play when it comes to baby sizes by weight. Those mentioned above are just some of them.