Objective: To find out if maternal nutritional habits are associated with the birth of macrosomic babies in Nigeria Design: This was a cross-sectional retrospective study of the nutritional habits of mothers of macrosomic babies and mothers of normal (non-macrosomic) babies attending a post natal clinic in Nigeria Setting: This study was carried out in St Philomena’s Hospital, Benin City, Nigeria, a maternity hospital, which has a large clientele because of its accessibility and affordability. Participants: Seventy five (75) mothers of macrosomic babies and 93 mothers of normal (non-macrosomic) babies Results: There was a significant difference between the frequencies at which mothers of macrosomic and normal babies ingested similar qualitative amounts of the staple high glycemic index diets. There was also a significant difference between the frequencies at which mothers of macrosomic and normal babies ingested similar qualitative amounts of low glycemic index diet used in this study. Most of the mothers of macrosomic babies indulged in soft drinks at frequencies, which were significantly different from the frequencies at which mothers of normal babies indulged in them. There was however no significant difference between the frequencies at which mothers of macrosomic and normal babies indulged in cocoa drinks. There was also a significant difference between the usage of vegetables by mothers of macrosomic and normal babies. Conclusion: The dietary factors that predispose to fetal macrosomia are frequent ingestion of high glycemic index diets and soft drinks and the avoidance of dietary fibers.