Smoking while pregnant may harm child's kidney: study

Moms-to-be, take note! Smoking during pregnancy may cause damage to your child's kidneys, a new study has warned.
Researchers from Kyoto University in Japan found that young children whose mothers smoked while pregnant were more likely to show signs of kidney damage compared to those born from nonsmoking mothers.
They conducted a population-based retrospective study using a database of health check-ups from pregnancy to three years of age in Japan.
The investigators looked for the presence of proteinuria - or elevated protein in the urine, which is a sign of reduced kidney function - in urinary tests from 44,595 children.

In the population examined, 4.4 per cent of women smoked only before pregnancy and 16.7 per cent continued smoking while pregnant.
The frequencies of proteinuria in the child at age three were 1.7 per cent when mothers continued to smoke during pregnancy, 1.6 per cent when moms stopped smoking during pregnancy and 1.3 per cent when mothers were nonsmokers, respectively.

Maternal smoking during pregnancy was associated with a 1.24-times increased risk of child proteinuria compared with no exposure to maternal smoking during pregnancy.
"Maternal smoking during pregnancy is known to be associated with preterm birth, low birth weight, and neonatal asphyxia. The findings from this study suggest an additional adverse effects of maternal smoking during pregnancy," said Koji Kawakami from Kyoto University.

"Prevention of child proteinuria is important since child proteinuria can lead to development of chronic kidney disease in adulthood and ultimately end stage renal disease," said Kawakami.
The study appears in the Clinical Journal of the American Society of Nephrology (CJASN).