CBNNews.com - A study finds that more than one-third of expectant mothers having elective c-sections, scheduled delivery before the recommended 39 weeks. But doing so can harm the baby.

Little Jake Moreno came into the world healthy, perhaps because his mom and doctor waited long enough. Jake was delivered by c-section, a surgery that's often scheduled weeks in advance. Even though the normal gestation period is 40 weeks, many people schedule their c-sections for well before then. Why?

Dr. Judy Aschner of Vanderbilt University Medical Center says the reason is convenience.

"Making sure you deliver when your obstetrician is available, or on Grandpa Joe's birthday," she said.

However, a new study says c-section babies born at 38 weeks are 50-percent more likely to go to the intensive care unit, 70-percent more likely to have infections that call for antibiotics and 200-percent more likely to develop respiratory distress, serious breathing problems which can require a ventilator.

The very last weeks of pregnancy are when the baby's lungs and brain are developing rapidly. Cutting pregnancy short could interfere with that growth.

Research indicates c-section babies are healthiest when delivered between 39 and 41 weeks.

So why do doctors perform them earlier than that?

Dr. Katherine Economy of Brigham & Women's Hospital said this should be a wake-up call for doctors.

"I think probably because they don't fully appreciate the risks that this highlights and this is a red flag, this is a wake-up call," she said.

A call that reminds doctors and expectant parents that it's not what's most convenient, but what's best for baby that matters most.

*Original broadcast January 21, 2009.