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).

根据美国儿科学会(AAP), “development is not a race, and babies develop at their own pace”(1).Therefore, even premature babies who experience developmental delays will gradually reachdevelopmental 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

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 inpremature babieswith 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

Source:Exploring the Decline in the Singleton Preterm Birth Rate in the United States

Weight, Height, And Head Circumference Growth In Premature Babies

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.

• Theweight gainedcan 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).

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

• 婴儿的实足年龄是绝对的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.

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 theapproximate values对身高、体重、头周长both preterm infant girls and boys. The value given is the 50th percentile, which is a median number(6).

Growth charts for premature infants

Weight, height, and head circumference of premature infant girls

Gestational Age In Weeks	Weight In Kilograms	Height In Centimeters	Head Circumference In Centimeters
24	0.6kg	30cm	21.1cm
26	0.8kg	33cm	23cm
28	1kg	35.6cm	25cm
30	1.3kg	38.5cm	27cm
32	1.7kg	41.1cm	29cm
34	2.1kg	44cm	30.5cm
36	2.6kg	46.5cm	32.1cm
38	3.1kg	48.5cm	33.5cm
40	3.4kg	50.5cm	34.9cm

Weight, height, and head circumference of premature infant boys

Gestational Age In Weeks	Weight In Kilograms	Height In Centimeters	Head Circumference In Centimeters
24	0.65kg	31cm	22cm
26	0.83kg	34cm	23.5cm
28	1.1kg	36.5cm	25.8cm
30	1.4kg	39cm	27.5cm
32	1.8kg	42cm	29.5cm
34	2.25kg	44.9cm	31cm
36	2.7kg	47cm	32.8cm
38	3.2kg	49.5cm	34cm
40	3.6kg	51cm	35cm

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.

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.

2. Formula or breast milk through tube feeding:Once yourbaby’s digestive systemis 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 expressedbreast milkthrough a feeding bottle. In the case of preterm orpremature 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 forhealthy growth. If required, the doctor may recommend this.

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