Changes in maternal characteristics in Nova Scotia Canada from 1988 to 2001

Background: Maternal characteristics such as age, parity, smoking status, pre-pregnancy weight and pregnancy weight gain have changed in many industrialized countries in recent years. Many of these changes have not been adequately described at a population level. The purpose of this study was to describe recent trends in selected maternal characteristics in Nova Scotia. Methods: Data from a population-based perinatal database were used to examine changes in maternal age, parity, smoking, pre-pregnancy weight, delivery weight and pregnancy wweight gain among all deliveries between 1988 and 2001. Results: The proportion of deliveries to women >= 35 years increased by 84% over the study period from 7.0% in 1988-1991 to 12.9% in 1998-2000, while deliveries to women >= 40 years increased by more than 100%. The number of nulliparous women >= 35 years also increased significantly. The overall prevalence of smoking decreased from 32.7% in 1988-1991 to 25.1 % in 1998-2001, however the prevalence of smoking among women < 20 years did not change over the study period and was almost 50%. The proportion of women with a pre-pregnancy weight of >= 90 kilograms (kg) increased by 165% from 4.1 % in 1988-1991 to 10.7% in 1998-2001. The proportion of women with pregnancy weight gain of < 7 kg and >= 18 kg increased by 37% and 13%, respectively. Conclusion: Dramatic changes have occurred in several important maternal characteristics and there is evidence of ongoing change. Continuation of these trends is likely to impact on future obstetric practice and perinatal health.