Clinical birthweight standards for a total population in the 1980s.

OBJECTIVE

To derive clinical standards for singleton birthweight in a population based on area of residence.

DESIGN

Analysis of variables recorded in Aberdeen Maternity and Neonatal Databank, calculating for each birth a standardised birthweight score, taking account of determining factors.

SUBJECTS

All singleton live births of 32 to 42 weeks gestation to Aberdeen City District residents from 1979 to 1983.

RESULTS

Basic standards of birthweight are presented correcting for gestational age, sex of the baby and parity of the mother. Birthweight is not normally distributed and empirical data are presented rather than smoothed curves. Adjustment for maternal height is straightforward but adjustment for maternal weight must take account of the gestation at which the woman was weighed. A method of calculating the appropriate correction for height and weight is described in detail.

CONCLUSION

Birthweight is not normally distributed at each week of gestation. Standardisation for parity, gestation and sex of the baby is essential, but adjustment for maternal size is complex.