Complex trauma and developmental trauma are terms used to describe chronic relational trauma and stress throughout childhood, with developmental trauma emphasizing on episodic shock experiences during the formative years.
An article written on Developmental Trauma Disorder by Dr Bessel Van der Kolk, reads:
The traumatic stress field has adopted the term “Complex Trauma” to describe the experience of multiple and/or chronic and prolonged, developmentally adverse traumatic events, most often of an interpersonal nature (e.g., sexual or physical abuse, war, community violence) and early-life onset. These exposures often occur within the child’s caregiving system and include physical, emotional, and educational neglect and child maltreatment beginning in early childhood.
There is very subtle difference between complex trauma and developmental trauma. For the ease of understanding, complex trauma and developmental trauma is used interchangeably and they both mean the same here.
Developmental trauma is experienced not only on what was being done unto a child, but also encompassed what was essential but missing to meet developmental needs of a growing child. Many a times, it is harder to witness the direct impact on one's life when developmental needs such as having emotionally attuned parents is not recognized and paid enough attention on. Despite many ground breaking studies and continual assertation from developmental psychologists in the past hundred years on how maternal (as well as paternal) emotional deprivation due to prolonged separation, and poor maternal and paternal attitude has a lifelong impact on children, the public is still largely oblivious and in fact emotionally numbed about it. This makes me wonder how parents who are emotionally neglectful to their children have suffered emotional neglect themselves. Many may have experienced adverse childhood events and are still coping silently.
According to the Adverse Childhood Experiences Study (ACEs), "childhood experiences, both positive and negative, have a tremendous impact on future violence victimization and perpetration, and lifelong health and opportunity. As such, early experiences are an important public health issue". Here is the questionnaire used in ACEs. The more "yes" you have on the questionnaire, the higher is your risk of developing physical and mental health problems in the later years. Note however the ACE study did not factor in positive life events/factors which can help to mitigate the effects ACE has on individual.