Want to Increase a Baby’s Fracture Risk? Smoke.

What is one of the most reliable methods of increasing any human being’s risk of a musculoskeletal fracture? Smoking—particularly by pregnant women.

How predictable is this phenomenon? A massive new study out of Sweden has answers. The paper, “Maternal smoking during pregnancy and fractures in offspring: national register based sibling comparison study,” was published in the January 29, 2020 edition of the British Medical Journal.

Citing a lack of clarity in the data, co-author Judith Brand, Ph.D. explained to OTW why she and her colleagues embarked on this study: “Smoking during pregnancy is a well-known risk factor for fetal growth restriction and low infant birth weight, but whether it influences offspring bone health and fracture risk after birth and later during childhood and early adulthood is less well understood.”

“In a recent study with repeat ultrasound data we found that the effect of maternal smoking during pregnancy on fetal growth was most pronounced for femur length, a marker of linear skeletal growth. However, results from studies investigating associations with bone mass and fractures in children and adolescents have been mixed.”

“To inform public health practice about the importance of early life factors in disease risk and prevention, we aimed to determine if fetal exposure to maternal smoking influences the risk of fractures, and whether this is a long-lasting effect.”

Using a national register from Sweden, Brand and her colleagues collected records from 1,680,307 people born in Sweden between 1983 and 2000 to women who smoked (n=377,367, 22.5%) and did not smoke (n=1,302,940) in early pregnancy. Follow-up was carried out until December 31, 2014.

According to Dr. Brand, the data clearly shows that the first year of life is the most vital. “We found that maternal smoking during pregnancy results in a small increased risk of bone fractures in infancy in a dose-dependent manner but does not result in a raised risk of fractures beyond the first year of life during childhood and early adulthood when controlling for other factors. Since the incidence of fractures during the first year of life is low, we found only a small difference in absolute numbers of fractures when comparing infants exposed with those unexposed to prenatal smoking.”

“Despite the fact that the risk of infant fractures observed with maternal smoking during pregnancy was small, our study suggests that tobacco-control programs which help reproductive-age and pregnant women to stop or reduce smoking may not only minimize the risk of adverse birth outcomes, but also prevent babies from suffering a fracture during their first year of life. Our work also indicates that prenatal exposure to maternal smoking does not appear to have a long-lasting biological influence on fracture risk later in childhood and early adulthood.”