The relation between antenatal care and birth weight.

The relation between gestational age at first antenatal visit and infant's birth weight was investigated in a cohort study of 846 primiparas living in the City of Dundee, Scotland, whose first antenatal visit was between 1 May 1985 and 30 April 1986. The earlier in pregnancy the first antenatal visit the greater the infants' birth weights tended to be (p < 0.01). The relation was independent of gestational age at birth, mother's age and height, social class, tobacco and alcohol consumption and the child's sex. The result supports similar findings elsewhere, but is more robust in that, in contrast to other studies, all birth weights were measured on a single electronic scale and the effects of maternal tobacco and alcohol consumption on birth weight were taken into account in the analysis. The mechanism of the effect remains to be determined but needs to be identified as it may indicate possible preventive measures for the benefit of future children.