evidence: Deaths associated with whooping cough are rare but most commonly occur in infants. That's why it's so important for pregnant women — and other people who will have close contact with an infant — to be vaccinated against whooping cough. [...] In infants — especially those under 6 months of age — complications from whooping cough are more severe and may include: [...] Because infants and toddlers are at greatest risk of complications from whooping cough, they're more likely to need treatment in a hospital. Complications can be life-threatening for infants younger than 6 months old.