Now Playing: DHA May Have No Real Benefits for Expecting Moms

Now Playing: Does Depression Increase Surgery Death Risk?

Now Playing: Talk to Your Parents About Depression

Now Playing: Managing Your Child's Allergies While They're Away

Now Playing: The Cuddle Hormone

Now Playing: Examining Lung Cancer Without Surgery

Now Playing: Antiretroviral Drugs May Prevent HIV Infection

Now Playing: How To Treat a Child's Ear Infection

Now Playing: Best Way to Screen for Breast Cancer?

Now Playing: Chronic Pot Users at Higher Risk for Brain Issues

Now Playing: Detecting Heart Failure

Now Playing: Exercise May Be a Deterrent for Uterine Cancer

Now Playing: Are Parents Falling Short on Teens' Health?

Now Playing: Reconstructive Breast Implants: Silicone or Saline

Now Playing: Hyper-Texting Teens Linked to Risky Behavior

Now Playing: Is Genomic Cancer Screening Reliable?

Now Playing: Alleviating Flu Symptoms: What Works Best?

Now Playing: DHA Pills have No Benefit for Alzheimer's Patients

Now Playing: The Dangers of Alcohol

Now Playing: Doctors Under-Reported Endoscopy Complications