Average Newborn Weight Dropping in the US

This has been happening for 15 years

By on January 22nd, 2010 12:05 GMT
The average weight that babies have at birth is one of the clearest indicators of their health, common knowledge has it. The heavier the child, the larger the chances that it will turn out fine. Conversely, children that are underweight require special treatment in the first few weeks of life, which may leave them exposed to harm later on in life. A new investigation was able to determine that, between 1990 and 2005, the average weight of a newborn dropped by about 1.83 ounces (52 grams). Additionally, it was also discovered that the most significant drop was recorded in a group of mothers that seemed the most unlikely to experience a decline of this type, LiveScience reports.

One of the sharpest levels of decrease was recorded in the case of white women, who were considered to be the least exposed to at risk. Factors such as marriage, the lack of nicotine addiction, higher education, early prenatal care and normal delivery made researchers believe that this subgroup would be set aside from the general trend. However, these women surprised investigators the most. Their babies dropped in average weight by 2.78 ounces (79 grams) in 15 years, which is more than the national level. This state of affair also makes many researchers wonder what may have caused this drop, particularly in this subgroup.

The study also found that the gestation period of women was also reduced, on average by about two days. “A logical conclusion might be that trends in obstetric management, such as greater use of cesarean delivery and induction of labor, might account for these decreases in birth weight and gestation length. However, our analysis showed that this was not the case,” Harvard Medical School (HMS) Assistant Professor of Population Medicine Emily Oken says. She was also a researcher on the recent investigation.

The team plans to continue this line of study, and to conduct research that will also incorporate a number of other factors that this paper did not take into account. Some of these influences refer to the diets would-be mothers have, the amount of physical activity they make, how much stress they are subjected to during pregnancy, as well as the level of exposure to environmental toxins, among others. Also, the group adds, it could be that the recent drop in birth weight may be the reversal of a growing trend, registered many years ago.

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Babies' average birth weight has been decreasing for the past 15 years, a new study shows
   Babies' average birth weight has been decreasing for the past 15 years, a new study shows