Besides smoking and drinking alcohol, parents' health including obesity and poor diet can have "profound implications" for the growth, development and long-term health of their children before their conception, says a series of studies published in the journal Lancet.

The findings showed that smoking, high alcohol and caffeine intake, diet, obesity and malnutrition in either or both parents, potentially increases a child's lifelong risk of heart attacks, stroke, diabetes, immune and neurological diseases.