Despite a reduction in overall maternal mortality in the United Kingdom (UK) during recent decades, maternal mortality rates over the previous six years have started to increase (Knight et al. 2019), and maternal deaths associated with pre-existing physical and/or psychological comorbidities are increasing nationally and globally (Nair et al. 2017). Surveillance data from the UK and Ireland suggests that most women who died during or following pregnancy in the period 2015 to 2017 had multiple health problems and/or additional complex social factors (Knight et al. 2019). This is mirrored in maternal mortality case reviews in other high-income countries including United States of America (USA) (Creanga et al. 2015), Australia (Australian Institute of Health and Welfare 2017) and New Zealand (Perinatal and Maternal Mortality Review Committee 2018).

Whilst maternal mortality rates in other high-income countries have also decreased over the past two decades, ranging from 3 to 12 deaths per 100,000 live births (WHO 2018a), severe maternal morbidity rates are increasing (Gellar et al. 2018), as a consequence of pre-existing and pregnancy related health problems, often reflecting multiple complex health and social needs. In the USA for example, overall severe maternal morbidity rates increased from 74 per 10,000 hospital births in 1998–99 to 163 in 2010–11 (Creanga et al. 2014). In the UK and Ireland more than two-thirds (68%) of the women who died during or after pregnancy in the triennial period 2014-2016 were known to have pre-existing medical problems (Knight et al. 2018). Conditions associated with increased maternal morbidity include obesity (Dudenhausen 2015, NHSE 2018a) diabetes (Coton et al. 2016, Feig et al. 2018) cardiac disease (Roos-Hesselink 2019) and severe mental illness (Estrin et al. 2019, Xu et al. 2014). Increasing numbers of women have physical and/or psychological comorbidities prior to becoming pregnant (Molyneaux et al. 2014, Ruhstaller et al. 2017, Kumpulainen 2018). These women are at greater risk of adverse pregnancy outcomes than women in the general pregnant population (Mhyre et al. 2011, Nair et al. 2015) and it is imperative that maternity policy acknowledges and addresses the impact of the changing health-profile of women to consider how to prevent or at least reduce maternal morbidity.