Factors associated with the timing of the first prenatal ultrasound in Canada

The aim of this study was to investigate the factors associated with the timing of the first prenatal ultrasound in Canada.

This was a secondary data analysis of the Maternity Experiences Survey, a cross-sectional survey covering different aspects of pregnancy, labour, birth and the post-partum period. Bivariate and multivariate multinomial logistic regressions were performed to assess the relationship between timing of first prenatal ultrasound and different independent variables.

68.4% of Canadian women received an optimally timed first prenatal ultrasound, 27.4% received early ultrasounds and 4.3% received late ultrasound. The highest prevalence of early ultrasound was in Ontario (33.3%) and the lowest was in Manitoba (13.3%). The highest prevalence of late ultrasound was found in Manitoba (12.1%) and the lowest was in British Columbia and Ontario (3.5% each). The highest prevalence of optimal timing of first prenatal ultrasound was in Quebec (77%) and the lowest was in Ontario (63.2%). Factors influencing the timing of ultrasound included: Early - maternal age < 20 (adjusted OR = 0.54, 95%CI:0.34-0.84), alcohol use during pregnancy (adjusted OR = 0.69, 95%CI:0.53-0.90), history of premature birth (adjusted OR = 1.41, 95%CI:1.06-1.89), multiparity (adjusted OR = 0.67, 95%CI:0.57-0.78), born outside of Canada (adjusted OR = 0.82, 95%CI:0.67-0.99), prenatal care in Newfoundland and Labrador (adjusted OR = 1.66, 95%CI:1.20-1.30), Nova Scotia (adjusted OR = 1.68, 95%CI:1.25-2.28), Ontario (adjusted OR = 2.16, 95%CI:1.76-2.65), Saskatchewan (adjusted OR = 1.50, 95%CI:1.05-2.14), Alberta (adjusted OR = 1.37, 95%CI:1.05-1.77) British Columbia (adjusted OR = 1.90, 95%CI:1.45-2.50) and Manitoba (adjusted OR = 0.66, 95%CI:0.45-0.98) Late - unintended pregnancy (adjusted OR = 1.89, 95%CI:1.38-2.59), born outside of Canada (adjusted OR = 1.75, 95%CI:1.14-2.68), prenatal care in Manitoba (adjusted OR = 2.88, 95%CI:1.64-5.05) and the Territories (adjusted OR = 4.50, 95%CI:2.27-8.93). An interaction between history of miscarriage and having 'other' prenatal care provider significantly affected timing of ultrasound (adjusted OR = 0.31, 95%CI:0.14-0.66).

Only 68% of Canadian women received an optimally timed prenatal ultrasound which was influenced by several factors including province of prenatal care, maternal age and country of birth, and an interaction effect between prenatal care provider and history of miscarriage. These findings establish a baseline of factors influencing the timing of prenatal ultrasound in Canada, which can be built upon by future studies.