Table 2 Stepwise thematic synthesis

Step 1: Data collated under question derived from study aims and independently reviewed by researchers, for example observations concerning 'understanding healthy growth/size' included:

-the word 'normal' frequently used by mothers e.g. "you don't want him to be seven feet tall, you just want him to be normal, like everyone else." [20]

-mothers of children with faltering growth were reported as tending to underestimate the extent of their child's thinness

-a preference for mid-range body sizes

Step 2: Themes produced by each researcher were compared and a consolidated list produced. For example, themes under 'understanding healthy growth/size' included:

Normal for family; "you look at me and his father, so he's not gonna be little either." (low income mother)[28]

Predeteremined: "he's finally taking the form he's supposed to have." (WIC mothers)[37]

Normal for population;" normal, like everyone else." [20]

Preference for mid-range body sizes[43]

Reaching "normal" size and development was key for many parents particularly for parents of low birth-weight infants

Step 3: Clustering of themes. When the themes falling under each review question were clustered around common dimensions. For example clusters under 'understanding healthy growth/size' were:

Themes referring to norms of healthy size or growth

Themes which explained differences from these norms (e.g. 'medical' causes)

Themes which referred to seen (e.g. nutrition) or unseen (e.g. hereditary characteristics) determinants of size/growth

Step 4: Agreed synthesis produced; example assessment of size/growth

Constructing size norms

Seven studies reported data on how participants assessed or defined normal size [20,28,31,37,38,42–44] Four themes emerged;

1. Medical definitions, including the use of growth charts [37,38,42] "I take her to clinic where they measure her height and her weight. They show me ... what is the normal height for children her age" (WIC mother)

2. Comparisons to other children in the community. [20,31,43,44] "you just want him to be normal, like everyone else." (mother) [20]

3. Comparison with family members. [28,37] "She's just a little below average as far as the children in the family" (WIC mother) [37]

4. One study reported use of clothing sizes; "if they are not fitting in the clothes they should be fitting in, they're not average" (WIC mother) [37]