Smaller babies prone to depression

WASHINGTON (Reuters) - Plump babies may really be happier babies, Canadian and British researchers reported on Monday in a study that found people who had a low birth weight were more likely to have depression and anxiety later in life.

Adverse conditions in the womb that interfere with a baby's growth may also cause brain differences, the researchers report in the December issue of Biological Psychiatry.

Ian Colman of the University of Alberta and colleagues in Britain studied the records of 4,600 Britons born in 1946 who took part in a 40-year study.

"We found that even people who had just mild or moderate symptoms of depression or anxiety over their life course were smaller babies than those who had better mental health," Colman said in a statement.

"It suggests a dose-response relationship. As birth weight progressively decreases, it's more likely that an individual will suffer from mood disorders later in life."

The researchers simply looked at medical records and did not examine a possible cause. Colman said it is possible that when mothers are stressed, stress hormones are passing through the placenta to the foetus.

"If this theory is correct, you would find that when stressful events occur, the people who were smaller babies would be more likely to become depressed or anxious," he said.

"One of the surprising findings from our research was that people who had worse mental health throughout their lives had also reached developmental milestones, like standing and walking for the first time, later in life than those who had better mental health."

The researchers did not look for any absolute weight but said there was a clear trend.