1.   Perinatal mortality is measured by the perinatal mortality ratio.

2.   Standardised mortality ratios from cardiovascular disease showed no trend with placental weight.

3.   The lack of a gold standard for health service need was a reason for using standardised mortality ratio in the RAWP formula.

4.   There were no trends in standardised mortality ratios from cardiovascular disease or other causes with the number of previous pregnancies.

5.   We also calculated standardised mortality ratios for all hypertensive patients.

6.   It can be shown algebraically that so that cohort probabilities can be estimated from mortality ratios.