Define Factors that effect birth weight and gestational duration?

A WHO review has identified 43 factors that influenced birth weight and gestational duration. They are grouped into seven categories for convenience. These include:

1) Genetics and constitution (e.g. sex of the baby)

2) Demographic and psycho social factors (e.g. age of the mother)

3) Obstetric factures (e.g. Parity)

4) Nutritional factors

5) Maternal morbidity during pregnancy

6) Toxic exposures (e.g. cigarette smoking)

7) Antenatal care (Number of visits and quality of care)