Cigarette smoke, whether one is the smoker or the one exposed to second hand or even third hand smoke, has detrimental and measurable health effects. A variety of studies have been conducted that connect cigarette smoking in parents to a wide variety of health issues in their children, from obesity to asthma. Two studies appearing in the July issue of the journal Pediatrics provide strong additional evidence of the harmful affects cigarette smoking can have on children whose parents smoke.

In one study, “Maternal Smoking and Child Psychological Problems: Disentangling Causal and Noncausal Effects,” the researchers analyzed the effects of cigarette smoke on children whose mothers had smoked during pregnancy.

They discovered a direct connection between smoking during pregnancy and the resulting mental health of the child. An increased occurrence of hyperactivity, externalizing problems, and peer issues were attributed to maternal smoking during pregnancy after adjusting for other factors, including paternal smoking. The researchers believe there is an “intrauterine effect of maternal smoking on offspring.”

The other study, “Paternal Smoking Associated with Childhood Overweight: Evidence From the Hong Kong ‘Children of 1997′ Birth Cohort,” was conducted by the Department of Community Medicine and School of Public Health at the University of Hong Kong and examined the impact of cigarette smoke on children whose mothers did not smoke, in an attempt to determine whether cigarette smoke influenced body mass index (BMI).

The researchers found that in cases where the child was exposed to paternal cigarette smoking, there was a 16% increase in BMI versus children who had not been exposed to second-hand smoke after factoring out all other variables. The researchers are urging parents to eliminate children’s exposure to cigarette smoke during childhood. Childhood obesity is a major cause of depression and impacts quality of life, raising additional concerns about childhood exposure to second-hand smoke.