Temporal trends of key preconception indicators among women in Northern Ireland, UK: an analysis of maternity healthcare data 2011-2021.

Optimizing preconception health offers an opportunity to reverse unfavourable trends in modifiable risk factors and improve reproductive outcomes. This study aims to report the yearly prevalence of key biopsychosocial preconception indicators for over a decade, as reported at antenatal booking appointments in Northern Ireland (UK). The indicators include area-level deprivation, planned pregnancies, and body mass index (BMI) between 2011 and 2021, as well as pre- and early-pregnancy folic acid supplement use between 2015 and 2020. This population-based study was conducted using annual routinely collected maternity data from the Northern Ireland Maternity System (NIMATS). R, accessed via the UK Secure eResearch Platform, was used to calculate yearly proportions. Multinomial regression models explored the relationship between each preconception indicator and year of booking appointment. Patient and Public Involvement and Engagement were integrated throughout the study. Of the 255 117 pregnancies included between 2011 and 2021, 21.4% were from women living in the most deprived quintile and 70.6% from women who reported a planned pregnancy. Obesity rates increased over the study period (e.g. obesity class I: 12.0%-16.1%), and preconception folic acid supplement use remained inadequate, though the use of supplements containing 5 mg of folic acid increased between 2015 and 2020 (400 µg: 34.4%-30.03%; 5 mg: 3.6%-5.0%). Efforts are needed to reverse negative public health consequences of sub-optimal preconception health indicators. Notably, folic acid supplement use was predominantly initiated after conception, suggesting that a renewed focus is needed, particularly supporting women with the greatest need, such as those in the most deprived areas.