Your Baby's Growth & Weight Gain

by Susan Miller, BScN

Parents and health professionals alike want to be assured that a baby is growing and gaining weight well. For years now, baby and toddler growth charts have been the standard tool in tracking baby’s growth and weight, but growth charts alone do not tell the whole story. There are various important factors that must be taken into account when assessing your baby’s growth. There are noticeable differences between boys and girls, and between breastfed and formula-fed infants. Just like grownups, babies come in different shapes and sizes, and are not all alike when it comes to their rate of growth and weight gain.

Babies can lose up to seven to 10 per cent of their birth weight in the first days after birth. This weight loss is due to general fluid loss and having passed their first bowel movement, called meconium. It is now also recognized that the IV fluids that a mother may receive in labour can artificially increase her baby’s birth weight. Therefore it may appear that baby has lost a lot of weight when in fact it was just the extra fluids they received during the labour as did their mother. The more weight baby loses just after birth, the longer it will take to gain it back, but most have reached their birth weight again by about two weeks. After baby has regained his birth weight he will typically gain about one ounce (30 g) a day for the first two months or so. Then, from two to six months the average breastfed baby gains about a 1⁄2 ounce (15 g) per day. It is important to know that weight gain in breastfed infants often slows down between the third and sixth months.

There is a general “rule of thumb” that babies will double their birth weight by four to five months of age. From six months to a year, babies are typically gaining only 3⁄4 of a pound a month. At one year of age babies have usually tripled their birth weight.

Growth in length averages about a 1⁄2 inch per month, and growth in head circumference about a 1⁄4 inch per month. These are only guidelines and some babies will grow faster or slower than others. The trouble is, parents and health professionals put a lot of emphasis on the actual numbers, and this can cause worry and anxiety. When looking at an individual baby and assessing growth and weight gain, one must look at the whole picture, which includes the general appearance of the baby. This includes their healthy colour and body proportions as well as their activity and energy level, baby’s typical sleep, wake and feed patterns, and the baby’s level of contentment after feeding.

In June 2010, a joint committee comprised of the Dietitians of Canada, Canadian Paediatric Society, The College of Family Physicians of Canada, and Community Health Nurses Association of Canada made a collaborative decision to recommend that all health care professionals now use the same set of growth charts for the Canadian pediatric population to “monitor Optimal Child Growth in Canada.” The purpose of the routine use of standardized growth charts is to follow the baby’s growth so that problems, if they do exist, are identified early. The committee found that there was no standardized set of Canadian growth charts and health professionals commonly used different growth charts, leading to inconsistencies in assessment of typical growth and weight gain. Often these charts have been developed by formula companies, and are based on formula-fed infants and may still be used by some physicians. The joint committee cautions that “growth rate of an exclusively breastfed infant plotted on charts that include formula-fed infants might lead to inappropriate counselling to discontinue breastfeeding.” In order to ensure more consistency, the joint committee recommended that health professionals in Canada use the growth charts developed by the World Health Organization (WHO).

The WHO growth charts were developed using data from six countries—Brazil, Ghana, India, Norway, Oman and the USA—and are now being used in a number of countries throughout the world. It is interesting to note that children around the world grow similarly when environmental conditions are favourable to growth. Children thrive when they have access to good nutrition and health care, and live in smoke-free households.

When plotting and recording baby’s weight and growth, measurements need to be made carefully and consistently, as inaccurate measurements may lead to faulty conclusions. For example, one person may measure length or head circumference differently than the next person. Scales need to be accurate and preferably the same scale should be used each time baby is weighed. The baby should always be naked when weighed.

Babies born before 37 weeks of pregnancy are considered premature, and therefore growth comparison is based on corrected age. This means that a baby born 5 weeks early is considered to be only one week old for assessing growth and development when he is actually six weeks old.

Other factors to take into consideration when assessing baby’s growth are the parents’ size and ethnicity, infant feeding method and any known health issues. A baby sick with a cold or other illness will naturally not gain as much as when she is well, and will need time to catch up again.

Using the new growth charts, it is recommended that your baby be weighed and measured within 1-2 weeks of birth, then at 1, 2, 4, 6, 9, 18 and 24 months of age. Most babies will fall within the 50th percentile range but that does not mean a baby under that range is any less healthy. Furthermore, a baby in the ninetieth percentile is not necessarily extra healthy; he is just bigger than most babies of his age. Parents need to know that their baby is following a predicted growth pattern that is right for him. A pattern of consistent weight gain and growth is more important than keeping up with a standard growth chart.

Susan Miller, R.N. BScN, is a Perinatal Educator and Certified Breastfeeding Counsellor, and has worked with pre and post-natal families in Greater Victoria for 30 years.