To determine whether the prevalence of stunting differed between an intervention group and a control group and to identify factors associated with the children’s linear growth.

This was a follow-up study of mother–child pairs who participated in a 2012–2015 cluster randomised controlled trial. Linear mixed effects models were performed to model the children’s linear growth and identify the determinants of child linear growth.

The study was conducted in two slums in Nairobi. The intervention group received monthly nutrition education and counselling (NEC) during pregnancy and infancy period.

A birth cohort of 1004 was followed up every 3 months after delivery to the 13th month. However, as a result of dropouts, a total of 438 mother–child pairs participated during the 55-month follow-up. The loss to follow-up baseline characteristics did not differ from those included for analysis.

Length-for-age z-scores decreased from birth to the 13th month, mean –1·42 (sd 2·04), with the control group (33·5 %) reporting a significantly higher prevalence of stunting than the intervention group (28·6 %). Conversely, the scores increased in the 55th month, mean –0·89 (sd 1·04), with significantly more males (16·5 %) stunted in the control group than in the intervention group (8·3 %). Being in the control group, being a male child, often vomiting/regurgitating food, mother’s stature of <154 cm and early weaning were negatively associated with children’s linear growth.

Home-based maternal NEC reduced stunting among under five years; however, the long-term benefits of this intervention on children’s health need to be elucidated.