Birth Weight
Educational information. Individual clinical review of this presentation by Dr. Ehsan is not yet documented. It does not replace personal medical evaluation.
Source: MedlinePlus, National Library of Medicine. Read the original source
MedlinePlus data edition September 26, 2026. Imported September 27, 2026. These dates do not indicate a new clinical review of the article.
What is birth weight?
Birth weight is the first weight of your baby, taken just after being born. A low birth weight means that the baby is less than 5 pounds, 8 ounces. A high birth weight means that the baby is more than 8 pounds, 13 ounces.
What can cause low birth weight?
A baby with a low birth weight can be born too small, too early (premature), or both. This can happen for many different reasons. They include:
- Health problems in the pregnant parent
- Taking certain medicines during pregnancy
- Substance use during pregnancy
- Infections during pregnancy
- Being pregnant with multiple babies
- Problems with the placenta, the organ that brings oxygen and nutrients to the baby
- Having small parents
- Genetic conditions in the baby
- Birth defects
What problems can low birth weight cause?
Babies with low birth weight may be more at risk of certain health problems. They include immediate problems, such as:
- Breathing problems
- Infections
- Hypoglycemia (low blood sugar)
- Jaundice
- Trouble keeping warm
There is also a higher risk of longer-term problems, including:
- Delayed motor and social development
- Learning disabilities
- Certain health conditions as an adult, such as heart disease, high blood pressure, diabetes, and obesity
What can cause high birth weight?
Causes of high birth weight can include:
- Having big parents
- Diabetes in the pregnant parent
- Certain genetic conditions
- Too much weight gain during pregnancy
What problems can high birth weight cause?
High birth weight can be a concern because it can make delivery of the baby difficult and raise the risk of birth injuries. The baby is at higher risk of problems with:
- Blood sugar
- Breathing problems
- Jaundice
Can birth weight problems be prevented?
You may be able to prevent some birth weight problems by:
- Getting regular checkups during pregnancy
- Getting the right amount of nutrition and calories during pregnancy
- Controlling your blood sugar if you have diabetes
- Avoiding substance use during pregnancy
Questions for your care team
General prompts to help prepare for your appointment.
- How does this information apply to my situation?
- Which symptoms or results need evaluation?
- Which tests are useful, and what can they tell us?
- What care options, benefits, and risks should we discuss?
- When should I seek urgent help, and whom should I call?
- When is follow-up, and how will we know whether the plan is working?
For a life-threatening emergency, call 911 in the U.S. or your local emergency number.
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