Growth in newborns

A baby’s weight, height and growth rate are usually considered an indicator of good health but little variation in these at birth and later can be normal. It’s therefore important to know what is normal and what to be concerned about.


Size of newborns

Most infant babies born after 37 weeks normally weigh between 5.5 and 8.8 pounds. While babies can be born heavier or lighter than this without having any problem, extra attention is usually paid to ensure that the baby is fine.

The size of a newborn is largely dependent on a number of factors which include:

  • Parents’ size: If parents are big and tall, their newborns may be larger than average while those that are petite may have smaller babies.
  • Multiple births: Mothers who are carrying twins or more children may have relatively smaller newborns since they share uterine space.
  • Birth order and gender: Slight differences in size are usually noticed at birth with girls being slightly smaller than male newborns. First babies are also sometimes smaller.
  • Mother’s health and nutrition: Lower birth weight can often be caused by things that affect the mother’s health during pregnancy. These include problems such as diabetes and obesity, which can lead to higher weight in newborns and harmful substances such as alcohol, cigarette and illegal drugs. Poor diet during pregnancy can affect the baby’s development and size at birth as well as their growth rate. A newborn might also be bigger if the mother gains too much weight during the pregnancy.
  • Baby’s health: The presence of medical problems such as infections acquired while in the womb or some birth defects can affect the weight of the newborn and his/her subsequent growth.
  • Maturity: babies born premature are generally smaller than other babies and lighter due to missed growth time in the womb and often require special medical care and observation in Neonatal ICU. The individual size and weight is largely affected by how early the baby is born. The baby can be low weight (less than 5.5 pounds) or very low weight (less than 3.31 pounds).


Newborns weight loss and growth rate

Newborns often lose about 7% to 10% of the birth weight due to loss of extra fluid in the first days. This weight is usually regained in the first weeks after birth. Over the first month, the newborns grow by about 1 ounce each day and between 1 and 1.5 inches in height.  This rapid growth takes place between 7 and 10 days then between 3 and 6 weeks.

Should I worry?

If you are concerned about too much weight loss in initial days after birth, you should talk to a doctor about it. The doctor will need to know the number of times you feed your baby and how much, how often he/she urinates and the number, volume and consistency of bowel movements. With this information, examination and close monitoring of the baby’s weight and height, the doctor should be able to determine if the baby is okay.

What to expect

Newborns weight and height at birth are not determinants of their size later in life. They often grow close to their parent’s size in adulthood. Genetics and nutrition also play a major role in babies’ growth so pay attention to your child’s diet.


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