This analysis examines the association between maternal characteristics, particularly body mass index (BMI) and infant birth weight in 1048 live infants. Mean reported pre pregnancy BMI of mothers was 23.74 kg/m2 (SD 4.21). The educational level of the mother's parents was independently associated with maternal BMI, those with higher educated parents having a lower reported BMI (F = 2.787, p = 0.029). Mean infant birth weight was 3493 g (SD 18.1) and there was a strong graduated relationship to estimated gestational age. In a sub-group of participating maternal grandmothers (n = 171), reported BMI was 26.7Kg/m2. The BMI of expectant mothers was significantly associated with their own mother's BMI. (r = 0.179, p = 0.005) in this sub-group. These preliminary findings, which will be investigated further with recorded height and weight information, suggest that familial factors are influential, perhaps through genetic predisposition or shared socio-cultural factors such as diet.