THURSDAY, Dec. 11 (HealthDay News) -- Late preterm birth puts newborns at increased risk for serious problems, according to U.S. researchers.

Dr. Joann Petrini of the March of Dimes and colleagues studied the neurological development of more than 140,00 preterm to full-term babies born between 2000 and 2004. And they found that late preterm babies (those born between 34 weeks and 36 weeks) were more than three times as likely as full-term babies to be diagnosed with cerebral palsy and were also at increased risk for developmental delay or mental retardation.

"The negative outcomes of many babies born late preterm can no longer be described as temporary or benign," Petrini said in a news release. She added that elective delivery through Caesarean section or induction should not be performed before 39 weeks unless medically necessary. Petrini also suggested that late preterm babies may benefit from neuron-developmental assessments.

The study is to be published in The Journal of Pediatrics.

Late preterm births account for more than 70 percent of preterm births, and there are more than half a million preterm babies born in the United States each year.

The "rates of preterm birth are increasing and the associated risks are a serious public health concern," Dr. Michael Kramer of McGill University in Montreal, wrote in an accompanying editorial in the journal. Induced labors and the increasing number of twins are among the factors contributing to the rise in preterm births.

Increased health risks associated with preterm birth may not always be due to early delivery itself, but could be linked to underlying problems in mothers, such as gestational diabetes, that may lead to early delivery, Kramer added.

He urged mothers and families to be aware of the risks when considering fertility treatments and induced labor.

Related MedlinePlus Pages:

• Cerebral Palsy
• Premature Babies