The Health Protection Agency says it is "very concerned" after the deaths of five newborns this year from whooping cough.
It follows a huge surge in cases - among all ages - in England and Wales.
The agency says it knows of 675 people diagnosed with whooping cough in June, bringing the total so far this year to 2,466.
The disease comes and goes in a cyclical pattern, with increased incidence occurring every three to four years.
By comparison, there were only 1,118 cases in the whole of 2011.
Health experts want parents to ensure they take their children for vaccinations as soon as they are due.
The recommended immunisation for whooping cough is offered to babies at two, three and four months of age, with a further dose before they start school.
But those younger than two-months-old remain vulnerable.
Claire Wright and Allan Steel from Sleaford, near Lincoln, are nursing their daughter Stacey back to health. At just three-weeks-old, she contracted the illness and is yet to fully recover three months on.
Mr Steel told Sky News it was a harrowing experience: "We did get really worried - she was on oxygen and she had so many tubes in her. It was horrible to see."
Stacey's mother added: "It's scary because she sounds like she's choking rather than coughing."
Doctors say the only way to protect babies as young as Stacey would be to immunise pregnant women, and hope some of that vaccine would be passed on to the foetus in the womb.
The Joint Committee of Vaccination and Immunisation , which advises the Department of Health, will make a decision next month on whether that should happen.
Whooping cough - so called because of the sound it causes when sufferers cough and then gasp for air - is rarely life-threatening for adults.
However, sufferers have been known to splutter so hard that they crack ribs, faint, vomit, or develop a hernia.