Not following a growth curve

Should I worry if my baby is not following a growth curve?

Growth charts can identify a problem and monitor the baby's response to an intervention. If the record of a baby’s growth doesn’t follow a typical pattern, it does not necessarily mean something is wrong. Moving up or down on a growth chart can be normal, can be caused by a weighing error, or it may also be a sign of a problem and the baby should be checked. Babies with breastfeeding problems or sick babies may lose weight or gain very little. Babies who are born large may grow slowly in the first three months and move into a lower curve. Babies who are underfed or born too small often grow quickly and move into a higher curve on the growth chart, catching up to where they should be, and over-fed ones can gain too quickly. 

A) Normal deviations from a growth curve

If your baby's weight is not following a growth curve, it means the measurements of your baby’s growth are not following a typical pattern. It does not necessarily mean something is wrong, but the baby should be checked. 

Slight deviations from a growth curve are normal. A well-fed baby may even move gradually from the 50th to the 85th percentile or from the 85th to the 50th. A baby born on the 50th percentile may fall to the 15th percentile, if the family is on the smaller side. Larger changes may be a sign of a problem. 

B) Weighing and plotting errors

This mother weighed her baby at three months because of the baby’s increasing unwillingness to breastfeed on the left breast. A weighing error showed that the baby had lost weight, and the mother assumed that the baby was not getting enough milk. The baby was actually gaining well and showed all the other signs of getting enough milk. The weighing error created a lot of unnecessary worry.

If just one point on the curve is unusual, it may be from a weighing or plotting error.

Mistakes can happen when weighing a baby. Consider that:

  • Normal functions, including feeding, peeing and stooling (pooping), affect the baby’s weight.
  • The baby may not have been weighed naked.
  • Different scales can give different readings when not calibrated properly.
  • Scales have different levels of accuracy. The best scales wait for the baby to stop moving and then give you an unchanging, locked number.
  • Someone may make a mistake and:
    • Include a towel or blanket, that was present under the baby, in the baby’s weight.
    • Not read the scale properly.
    • Write down the weight.
    • Mark the growth chart incorrectly.  

These issues can also affect the reading of the weight at birth.

Babies should be re-weighed and the weight re-entered on the growth chart, if a point looks odd. If there is no weighing error and the baby does not stay on a curve, the baby’s breastfeeding and health should be reviewed.

C) Slow weight gain by babies who are born large

The mother of this baby was diabetic; as a result he was born very large. His initial weight gain was slow. He ended up growing along the 50th percentile. He showed all the other signs of getting enough milk.

Some babies are born too big if their mothers:

  • Are diabetic (Farrar 2017).
  • Are obese (Gaudet 2014).
  • Have gained more than the recommended weight during pregnancy (Tian 2016).

These babies may be born at or above the 97th percentile or around 4 kilograms (8 pounds 13 ounces). They are essentially overweight. When breastfed, they tend to grow slowly for the first three months so their growth curves show them moving into lower percentiles (Eny 2018). However, they show all the other signs of getting enough milk.

These babies sometimes dip as low as the 50th percentile by the third month and then follow that curve. Going below the 50th percentile in this situation is not common unless the parents are very short.

D) Slow weight gain by premature babies

Without correcting for her early birth at 37 weeks, this baby appears to be growing under the 50th percentile (black dots). When her age is adjusted for her early birth, her growth is above the 50th percentile (red dots); this is her true growth curve.

Premature babies are born small. They should have their weights followed on a growth chart meant for premature babies. As they get older, growth charts for term babies from 0 to 6 months are used, but their age needs to be adjusted for their early birth. 

For example, consider a baby who was born at 37 weeks of gestation instead of the usual 40. At ten weeks after delivery, this baby should be considered only seven weeks old on a growth chart.

If their age is not adjusted, they will appear to be following a lower percentile than is actually the case. 

E) Slow weight gain by underfed babies

This baby did not gain until infant formula supplements were started. Before-feed and after-feed weights showed that the baby was taking in about 250 ml (8 oz) of milk per day from the breast and he required roughly 800 ml (27 oz) of infant formula supplements each day.

Babies with breastfeeding problems who do not take in enough milk can:

  • Lose weight.
  • Not gain.
  • Gain too slowly.

Sick babies can also behave in this way.

It is important to decide if the baby is underfed or sick in order to fix the problem. These babies should be in the care of a health-care provider.

F) Slow weight gain by sick babies

By one month of age, this baby was feeding for short periods, vomiting frequently, and not growing. Before-feed and after-feed weights showed that the baby was only taking in about 250 ml (8 oz) of breast milk each day. The mother could pump an additional 300 ml (10 oz) each day but the baby refused all supplements. The baby only started gaining after undergoing surgery for a twisted bowel at three months. He was temporarily supplemented with breast milk after surgery.

 Some sick babies may gain normally but others will gain slowly.

G) Rapid weight gain caused by overfeeding

This mother was worried that her baby was not getting enough milk by breastfeeding. The mother continued to breastfeed at all feeds and started supplementing with infant formula in the first week after birth. The amounts of infant formula increased over time and resulted in very rapid weight gain.

A baby may grow too quickly if over-supplemented with milk or forced to feed when not hungry. The latter is more common in bottle-fed babies.

Rarely, exclusively breastfed babies may grow very quickly.

H) Rapid weight gain by babies who were underfed

This baby’s mother had insufficient glandular tissue (type 1). As is common with otherwise healthy but underfed babies, this baby gained very quickly once supplements were started: 700 grams (24 oz) in seven days. He needed roughly 600 ml (20 oz) of infant formula supplements each day.

Some babies lose too much weight right after birth. A baby who was underfed after birth and later takes in enough milk will grow very quickly to regain the lost weight and then grow at a normal rate and follow a curve.

Older babies may also gain very quickly after supplements are started, if they were severely underfed. 

I) Rapid weight gain by babies who were born too small

Some babies are born with an abnormally low weight caused by a placenta that is not working well and not allowing enough nutrients to get to the baby. Doctors call these babies intra-uterine growth restricted (IUGR).

They are born thin and small. IUGR babies often grow quickly and catch up to where they should be (Santiago 2020). The growth chart will show the baby moving to higher curves. This is normal.

References

Eny KM, Chen S, Anderson LN, et al. TARGet Kids! Collaboration. Breastfeeding duration, maternal body mass index, and birth weight are associated with differences in body mass index growth trajectories in early childhood. Am J Clin Nutr. 2018 Apr 1;107(4):584-592
 
Farrar D, Duley L, Dowswell T, et al. Different strategies for diagnosing gestational diabetes to improve maternal and infant health. Cochrane Database Syst Rev. 2017 Aug 23;8:CD007122
 
Gaudet L, Ferraro ZM, Wen SW, et al. Maternal obesity and occurrence of fetal macrosomia: a systematic review and meta-analysis. Biomed Res Int. 2014;2014:640291

Santiago ACT, Cunha LPMD, Costa ML, et al. Cardiometabolic evaluation of small for gestational age children: protective effect of breast milk. Nutr Hosp. 2020 Dec 4

Tian C, Hu C, He X, et al. Excessive weight gain during pregnancy and risk of macrosomia: a meta-analysis. Arch Gynecol Obstet. 2016 Jan;293(1):29-35