NEW YORK (Reuters Health) — During adolescence, girls but not boys may be more likely to develop depression if they were born weighing less than about 5.5 pounds, new research suggests.“Parents and paediatricians of girls who were of low birth weight “should pay close attention to their mental health as they enter puberty,” write researchers in the medical journal, Archives of General Psychiatry.

Dr. Elizabeth Jane Costello, of Duke University Medical School, Durham, North Carolina and colleagues examined the relationship between low birth weight and depression in 1,420 boys and girls between nine and 16 years of age from 11 North Carolina counties.

Although only about 5.7 percent of girls in the study were born weighing less than 5.5 pounds, about 38 percent of these girls suffered one or more episodes of depression between the ages of 13 and 16 years.

By comparison, only 8.4 percent of girls the same age born with normal weight suffered at least one bout of depression.

Costello and colleagues estimate that 18 percent of cases of depression in adolescent girls may be linked with low birth weight.

On average, 23.5 percent of girls ages 13 to 16 years with low birth weights suffered depression each year compared with 3.4 percent of those with normal birth weights. The low birth weight-depression link was absent in boys, with no more than 4.9 percent of boys with depression, regardless of their birth weight.

Low birth weight was also not associated with an increased risk of any other psychiatric problem, such as anxiety disorders, in either boys or girls.

The authors propose that the potential for depression may lie dormant in individuals born with low birth weight, emerging under stressful conditions, such as adolescence.

In support of this, they point out that in the absence of adversity none of the low birth weight or normal birth weight adolescent girls had an episode of depression.

Yet, 20 percent of girls with low birth weight exposed to a single adverse event had an episode of depression compared with 4 percent of normal birth weight teen girls. The difference among girls with two adversities was even more marked, with 68 percent of low birth weight girls experiencing depression versus 20 percent of normal birth weight girls.