At the recent Noche de Ninos gala benefit for Children’s Hospital in Los Angeles, actress Jennifer Lopez revealed that she and her husband Marc Anthony took daughter Emme to undergo an MRI scan when she was only three weeks old. She and Anthony had found a lump on the baby’s head, and were terrified.

The baby turned out just fine, but Lopez said she told her husband, “You know if anything happens, I’m not going to be OK, you know that, right?” Emme is the twin sister of Lopez and Anthony’s son Max. The twins are now 15 months old.

But the health scare caused Jennifer to partner with the hospital to create the Maribel Foundation to provide medical services to less fortunate children. Lopez has also been an advocate of adults – particularly parents of young children – getting the pertussis, or whooping cough vaccine to help protect infants.

Cases of pertussis have been on the rise over the past decade, and parents can acquire the disease and pass it on to their children. The March of Dimes and sanofi Pasteur is aiming to raise awareness of the situation and encourage all adults who are in close contact with infants to get vaccinated with the adult version of the tetanus, diphtheria, and acellular pertussis vaccine. In babies, the disease can be severe enough to cause death.

Babies are at risk of contracting pertussis from adults until their entire first round of vaccinations is completed during the first 18 months of life.