Height And Weight Gain Growth Chart For Premature Babies

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Preterm or premature birth occurs when a woman delivers her baby before the 37th week of pregnancy. Various factors can cause preterm birth, but one of the most serious concerns is the babies’ low birth weight (LBW).

According to the American Academy of Pediatrics (AAP), “development is not a race, and babies develop at their own pace” (1). Therefore, even premature babies who experience developmental delays will gradually reach developmental milestones, including weight gain, if proper conditions are offered.

This post discusses premature babies’ weight gain and growth and provides a premature baby growth chart.

Understanding The Weight Of Premature Babies

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The average weight of a newborn is seven pounds (3.17 kilograms). But the average weight of a preterm infant is about five pounds (2.26 kilograms) or less. The exact weight depends on how early the baby is delivered, with infants born after 28 weeks of pregnancy weighing 2.3 pounds (one kilogram) (2).

There is a difference in premature babies with low birth weight, compared to babies who suffered intra uterine growth retardation, so called “Small for gestational age” babies.

In the United States, the preterm birth rate for non-Hispanic White mothers decreased by 1% from 7.44% in 2019 to 7.36% in 2020, while there were no significant changes for non-Hispanic Asian and Hispanic mothers. However, there were insignificant increases for non-Hispanic Black and non-Hispanic American Indian or Alaska Native mothers. In 2020, the singleton preterm birth rate was significantly higher for non-Hispanic Black mothers by about 65% compared to non-Hispanic White and non-Hispanic Asian mothers.

Preterm singleton birth rates in the US, based on the mother's race

Weight, Height, And Head Circumference Growth In Premature Babies

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The weight, height, and head circumference of a premature infant will vary depending on the gestational week of their birth and their overall health at birth. The following are some key points about the weight, height, and head circumference of premature babies:

Note that these are the average figures while the actual figures may differ from one baby to another.

• Premature infants are put in the neonatal intensive care unit (NICU) and ideally start gaining weight within a few days after birth.

• The weight gained can significantly differ among babies. A baby with a gestational age of 24 weeks (born after the 24th week of pregnancy) may attain five grams per day while those born at 33 weeks or later can put on as much as 30 grams per day (3).

• The desirable weight gain in babies who are born with a birth weight of more than two kilograms is 20-30 grams per day (4).

• The height of preterm babies increases by about 1.1 centimeters every week until the completion of the ideal gestational age, which is about 40 weeks.

• The chronological age of the baby is the absolute age, which is the time from the birth of a premature baby to the present. This age is also called postnatal age.

• A healthy premature infant is likely to show improvement first in the head circumference, followed by weight and height.

In the next section, we give you a detailed growth chart for premature infants.

Trivia

According to the World Health Organization, around 15 million babies are born prematurely every year. This means that more than one in every 10 babies is premature (10).

Premature Baby Growth Chart

The Fenton growth chart for preterm infants is most commonly used for assessing the growth milestones of a premature baby. The Fenton chart was created in 2003 by Dr. Tannis Fenton, who revised it in 2013 to accommodate the new standards suggested by the World Health Organization (5).

In the next section, we list the approximate values for height, weight, and head circumferences for both preterm infant girls and boys. The value given is the 50th percentile, which is a median number (6).

Growth charts for premature infants

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Weight, height, and head circumference of premature infant girls

Weight, height, and head circumference of premature infant boys

Source: Fenton Preterm Growth Chart Site, University of Calgary (7)

Not all babies develop the same way or at the same pace, as the growth at this stage depends on multiple factors. Doctors periodically assess a preterm baby in the NICU.

Note that the growth figures indicated by the doctor could be less or more than those mentioned in the chart. But as long as your doctor states that your baby is doing well, you can relax and look forward to taking your baby home from the NICU.

However, one thing you may still worry about is the baby’s nutrition as it can affect their weight significantly.

Trivia

Premature babies may be born early, but they know how to catch up in life. Famous personalities such as Mark Twain, Anna Pavlova, Isaac Newton, Stevie Wonder, and Pablo Picasso were all premature babies.

Nutrition For A Premature Baby

Premature babies often experience feeding difficulties and the doctors in the NICU will determine a premature baby’s feed after considering the gestational age and their overall health condition. Below are the sources of nourishment for a preterm infant:

1. Intravenous fluids: Early preterm babies will not be able to breastfeed and will require an intravenous delivery of nutrients and other fluids. The IV solution will be a mix of all the compounds that the baby will need to thrive and grow stronger.

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2. Formula or breast milk through tube feeding: Once your baby’s digestive system is a bit strong, they can receive breast milk or formula directly into their stomach through a sterile tube that goes through their nose or mouth. This form of feeding is called nasogastric or orogastric tube feeding.

The doctor will determine the nature of the feed. If the mother is lactating sufficiently, then she can express breast milk, which would be then given to the baby through tube feeding. The quantity of breast milk or formula increases gradually in this method.

3. Breastfeeding: If your baby is a late preterm infant (born between 34-37 weeks), then they may be able to breastfeed. Both the mother and baby will require some initial practice. But once the baby understands to latch to the nipple, you can breastfeed the premature baby just like you would a full-term baby.

If the baby has trouble latching, then you can provide expressed breast milk through a feeding bottle. In the case of preterm or premature delivery, breastmilk has more protein, minerals, and fat that the baby can easily digest (8). Breastmilk will also reduce the risk of intestinal infection.

4. Fortified formula: Breastmilk alone may not provide the nutrition that premature babies need to grow. They have a higher caloric requirement, usually around 120-kilocalories per kilogram of body weight per day (9). Fortified formula milk can provide the extra nutrition that preemies need, along with the right mix of vitamins and minerals for healthy growth. If required, the doctor may recommend this.

Image: IStock

Infographic: What Are The Health Challenges Of Extremely Preterm Babies?

Extremely premature babies are born before the 28th week. Chances of survival are rare if born before 23 weeks. Babies born at 23 to 25 weeks have a better chance of survival with medical care. However, it is not possible to rule out the risk of lifelong disabilities. Go through the infographic to know the health challenges of extremely preterm babies.

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Illustration: Momjunction Design Team

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Learn about preterm birth in this informative video. Understand its causes, recognize the signs and symptoms, and explore diagnosis and treatment options. A must-watch for expectant parents.

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Dr. Elna GibsonMBChB, MMed, Paeds

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