Girls born extremely prematurely may have an increased risk of depression from childhood through young adulthood.

Using Finnish birth and health registries, researchers studied 37,682 people diagnosed with mild, moderate or severe depression, comparing them with 148,795 healthy controls. The children were born between 1987 and 2007, and their average age at diagnosis was 16.

After adjusting for parents’ age, depression, substance abuse, smoking, socioeconomic status and other factors, the psychiatry study found that in girls, but not boys, younger gestational age was strongly associated with a diagnosis of depression in childhood, adolescence or young adulthood. Girls born before 28 weeks’ gestation were at roughly three times the risk for depression as those born at full term. After 28 weeks gestation, the association was no longer significant. The study is in the Journal of the American Academy of Child & Adolescent Psychiatry.

The authors suggest that the limited age range in the study of 5 to 25 years means that it was primarily early onset depression that was detected, and this may underestimate the effect in boys, who are typically diagnosed with depression at older ages.

“This is a huge sample,” said a co-author, Dr. Andre Sourander, a professor of child psychiatry at the University of Turku in Finland, “and we had many covariates for both mothers and fathers.” Even after considering all these other factors that may contribute to depression, “the findings remained significant,” he said.

Good Sleep Habits Tied to Lower Risk of Heart Failure

A combination of healthy sleep habits may help reduce the risk for heart failure, new research suggests.

Scientists studied 408,802 generally healthy people aged 27 to 73 between 2006 and 2010, collecting information on their sleep habits. Each person got a zero-to-five “healthy sleep score,” based on five healthy sleep practices: being a “morning person”; sleeping seven to eight hours a night; rarely or never snoring; rarely having insomnia; and rarely being excessively sleepy during the day.

Over an average follow-up of 10 years, there were 5,221 cases of heart failure. Compared with people who scored zero or one, those who scored two had a 15% reduced risk for heart failure; those who scored three had a 28% reduced risk; and those who scored four a 38% risk reduction. Those who scored a perfect five had a 42% lower risk of heart failure compared with those who scored zero or one.

The study, in the journal Circulation, controlled for smoking, alcohol intake, physical activity, diabetes, high blood pressure and other variables. It is an observational study, however, so it does not prove causality.

“We should consider all of these sleep behaviors together rather than treating them as separate phenomena,” said senior author Dr. Lu Qi, a professor of epidemiology at Tulane University. “People regulate their sleep as a whole, not as separate events.”

Vegetarian or Vegan? Watch Your Bone Health.

Vegetarian diets are generally considered healthy, but new research suggests they may have a significant risk: an increased chance of bone fractures.

Between 1993 and 2001, British researchers collected diet, health and behavioral data on 54,858 people, average age 50. They categorized them by diet: 29,380 meat eaters; 8,037 who ate fish but no meat; 15,499 vegetarians; and 1,982 vegans, who ate no meat, fish, dairy products or eggs. They followed them for an average of 18 years, tracking the number and location of fractures.

The study, in BMC Medicine, controlled for sex, physical activity, smoking, alcohol intake, dietary supplement use and other factors, and found that compared with meat eaters, vegetarians had a 9% increased risk for any fracture, and vegans a 43% increased risk.

Vegetarians and fish eaters had a roughly 25% increased risk for hip fracture, and the risk for hip fracture in vegans was more than twice that of meat eaters. The risk for leg fracture was 81% higher in vegans than in meat eaters.

The associations were weaker, but still significant, after additional adjustments for protein and calcium intake.

“It’s very important that vegetarians and vegans have adequate intakes of protein and calcium,” said the lead author, Tammy Y.N. Tong, a nutritional public health researcher at the University of Oxford. “If they can’t get it from diet, they should use supplements.”