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Commonly Used Chemicals Associated with Low Birth Weight

Research in China reveals that low-birth-weight infants (who suffer higher rates of death, disability, and impaired development than larger babies) have higher blood levels of phthalates than heavier newborns.

NEW YORK, NY, and SHANGHAI, CHINA (25 June 2009) — A study of 201 mothers and their newborns in China, conducted by the Population Council and colleagues, found that infants with low birth weight had consistently higher levels of phthalates in their umbilical cord blood and meconium (first bowel movement) than heavier infants. Phthalates, chemicals used to make plastics more flexible, are ubiquitous in the environment.

In particular, one phthalate, DBP, was associated with low birth weight. The higher the exposure to DBP, the lower the infant's birth weight. Another phthalate, DEHP, was associated with babies being shorter than normal. In 2008 the US Congress enacted a permanent ban on the manufacture, sale, distribution, and importation of children's toy and child care articles that contain DEHP and DBP. (A third phthalate, BBP, was also permanently banned, and three others were temporarily banned, pending a scientific review.)

"Numerous studies have found that the effects of phthalates are more significant in children than adults," explains Population Council Bixby Fellow Yunhui Zhang. "A fetus, because it is still in early stages of development, might have even greater susceptibility to the potentially adverse effects of phthalates."

Infants born weighing less than 5.5 pounds (2,500 grams) are considered to be of low birth weight. Almost a quarter of all babies born worldwide, and 8.2 percent of newborns in the United States, fall into this category. These babies, particularly the ones in developing countries, are more susceptible to postnatal complications and infections. They have a higher death rate than heavier infants. The study controlled for other factors known to contribute to low birth weight, including maternal malnutrition, lower socioeconomic status, and exposure to smoking or secondhand smoke.

According to Population Council biomedical scientist Renshan Ge, who conducted the research in China with Zhang and a team from Fudan University and the Second Military Medical University, "The results showed that prenatal phthalate exposure might be an environmental risk factor for low birth weight in infants." Their findings were published today online in the Journal of Pediatrics.

• Zhang, Yunhui, Ling Lin, Yang Cao, Bingheng Chen, Lixing Zheng, and Renshan Ge. "Phthalate levels and low birth weight: A nested case-control study of Chinese newborns," Journal of Pediatrics, published online, 25 June. (offsite link)
  
  

Read more about the action of endocrine disrupters on Leydig cells:

• "Study finds link between phthalates and low birth weight," Population Briefs, July 2009, p. 3 (PDF)
  
  

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