Infants born to healthy mothers are more resilient to pathogen exposure and likely to grow and develop to their full potential (ideal trajectory of steady health), whereas those born to unhealthy mothers (pre-term or with low birth weight) fall into a cycle of increased susceptibility to repeat infections, growth faltering, malnutrition and death (the vulnerable trajectory). Repeated illness dramatically reduces child’s potential for physical growth, development, and quality of life. Mothers who become pregnant again (dashed arrow) initiate a repeat cycle of sustained health or vulnerability, which can perpetuate for generations.