Adversity and stress early in life leads to long-term ill health and early death, a group of psychologists warn.
A series of studies suggest that childhood stress caused by poverty or abuse can lead to heart disease, inflammation, and speed up cell ageing.
The American Psychological Association meeting heard that early experiences "cast a long shadow" on health.
One UK expert said more and more evidence was suggesting a physical impact of stress in childhood.
In one study, researchers from the University of Pittsburgh looked at the relationship between living in poverty and early signs of heart disease in 200 healthy teenagers.
They found that those from the worst-off families had stiffer arteries and higher blood pressure.
A second piece of research by the same team showed children from poorer homes were more likely to interpret a series of mock social situations as threatening.
They also had higher blood pressure and heart rates and higher hostility and anger scores during three laboratory stress tasks.
It backs other research showing a link between a stressful childhood and future cardiovascular disease, said study leader Professor Karen Matthews.
She said unpredictable and stressful environments lead children to be "hyper vigilant" to perceived threats.
"Interactions with others then become a source of stress, which can increase arousal, blood pressure, inflammation levels and deplete the body's reserves.
"This sets up risk for cardiovascular disease."
Another study presented at the conference showed that childhood events such as the death of a parent or abuse can make people more vulnerable to the effects of stress in later life and even shorten lifespan.
Researchers at Ohio State University looked at a group of older adults - some of whom were carers for people with dementia.
They measured several markers of inflammation in the blood which can be signs of stress, as well as the length of telomeres - protective caps on the ends of chromosomes which have been linked to age-related diseases.
The 132 participants also answered a questionnaire on depression and past child abuse and neglect.
A third study reported some sort of physical, emotional or sexual abuse during childhood.
Those who did face adversity as children had shorter telomeres and increased levels of inflammation even after controlling for age, care-giving status, gender, body mass index, exercise and sleep.
Study leader Professor Janice Kiecolt-Glaser, said: "Our latest research shows that childhood adversity casts a long shadow on one's health and can lead to inflammation and cell ageing much earlier than for those who haven't experienced these events.
"Those reporting multiple adversities could shorten their lifespan by seven to 15 years," she added.
Dr Andrea Danese, a clinical lecturer at the Institute of Psychiatry in London, said such studies had to be interpreted carefully because there is a chance that people do not recall their childhoods accurately and you can only show an association not prove causality.
"But that doesn't mean I don't believe these results.
"The evidence is quite consistent.
"It's already been established that childhood stress has an effect on mental health and it now seems like it has an enduring effect on physical health."
He said that stress causes an increase in inflammatory proteins which could underpin the physical consequences suggested by the research.