OC13.03: “Inverting the pyramid” of antenatal care in Australia: implementation outcomes of the Initial Maternity Assessment and Planning Service

To describe key implementation outcomes over 2 years following successful establishment of the first trimester population-based initial maternity assessment and planning (IMAP) service. The IMAP (Initial Maternity Assessment and Planning) Service is a prospectively designed first trimester population-based expanded screening and assessment service established in 2021. In line with the RE-AIM implementation science framework, several implementation outcomes were defined at the time of design to provide ongoing measures of service success. These include Reach (number and proportion of eligible women accessing the service); Effectiveness (positive and negative service impacts including mean gestational age at first visit and subsequent allocation to low-risk or high-risk pathways); and Maintenance (degree by which initial changes in care are sustained over time). From 1st July 2021 until 30th June 2023, 6051 women eligible for local public maternity care were seen within the IMAP service. 68.4% of women visited within the recommended gestational window of 11 to 14 weeks gestation. The remaining 31.6% undertook a modified form of IMAP visit at >14 weeks gestation which focused on history-based risk assessments. Median gestational age at time of visit was 12 weeks (IQR 12-18) and 61.2% were allocated to low-risk community-based models of care. These findings have been sustained with gradual improvements over time since the service was established. This is the first study to describe key implementation outcomes of a population-based first trimester screening and assessment service which demonstrates the principles of inverting the pyramid of antenatal care. Fragmented early pregnancy care has been described in a range of healthcare settings and this study confirms the potential improvements in care provision with a redesigned approach to first trimester specialist maternity care.