The weight and length of a newborn baby is among the most sought-after information when loved ones hear the news that a little one has been born. While it's enjoyable to hear these vital statistics, weight and length are measured because they are valuable predictors about a newborn's health, and they also provide a suspected growth pattern to pediatricians. Keep in mind that averages indicate the most common weights and lengths for babies, and your baby might fall outside of these averages and still be completely healthy.
The Long and Short of It
Babies delivered at the standard 40-week mark measure an average of 20.16 inches long, according to BabyCenter.com. A baby born at 41 weeks gestation measures an average of 20.35 inches. A baby delivered between 38 and 39 weeks measures an average of between 19.61 inches and 19.96 inches. Of course, babies who are born prematurely tend to be smaller in length than babies who are born full-term.
Does Length Matter?
Being shorter or longer than the average length doesn't necessarily indicate a problem. In fact, the height of the baby's parents can play a role in how long a baby is at birth, so very tall parents might have a baby longer than the average, while shorter parents might have a baby that's smaller than the average, according to KidsHealth.org. Concern for a smaller-than-average baby can come into play in the case of premature births, however.
A Weighty Issue
Most babies born at 40 weeks gestation weigh an average of 7.63 pounds, according to BabyCenter.com. A baby who isn't born until 41 weeks gestation weighs an average of 7.93 pounds, and one who makes it to 42 weeks gestation weighs an average of 8.12 pounds. A baby born at 38 weeks, on the other hand, weighs an average of 6.8 pounds, BabyCenter.com notes. The averages are smaller for babies who are born prematurely.
What Does It Mean?
While there isn't as much concern when a baby is shorter or longer than average, being much lighter or much heavier is a cause for concern in many cases. According to the Lucile Packard Children's Hospital at Stanford, a baby who is small for her gestational age is at a greater risk for oxygen deficiencies, low blood sugar, a higher than normal red blood cell count and difficulty maintaining body temperature. Babies who are born much larger than average are at risk for low blood sugar and injury during the birthing process, according to the National Institutes of Health's MedlinePlus.