Among the eight United Nations Millennium Development Goals (MDGs), progress towards the fifth, to reduce maternal mortality by three quarters between 1990 and 2015, has been particularly slow [1–4]. Although a recent global review  suggests levels of maternal mortality in developing regions have fallen since 1990, it has become increasingly clear that significant improvements in health care for women are required if the goal is to be achieved. This is particularly the case for sub-Saharan Africa and South Asia, in which at least 87% of the estimated annual 342,900 maternal deaths worldwide occur according to recent estimates, with over 50% of all maternal deaths occurring in only six countries (India, Nigeria, Pakistan, Afghanistan, Ethiopia and the Democratic Republic of Congo).
Increasing the availability of skilled health professionals to supervise deliveries has been identified as a key strategy for reducing maternal deaths, with the proportion of births attended by a skilled birth attendant (SBA) adopted as a direct indicator for MDG5 [6, 7]. The global target is for at least 90% of births to be supervised by a SBA worldwide by 2015 . Overall, the proportion of SBA-births in developing regions increased from 53% in 1990 to 61% in 2007, yet in South Asia and sub-Saharan Africa this figure remained less than 50% . It is also of note that the proportion of SBA births in these regions is significantly lower in rural than in urban areas [10, 11].
Although it has proved difficult to establish a causal link between SBA births and maternal mortality rates , estimates suggest that SBA presence at delivery could prevent around 16% to 33% of maternal deaths . In addition, SBA attendance at birth may impact on rates of stillbirths and neonatal mortality related to intrapartum events. To this end, local and international effort focuses on improving access to SBA attendance at birth throughout the developing world, including activities such as training attendants, increasing access to health facilities and allocating health resources more equitably among rural and urban areas .
Despite concerted effort to increase SBA attendance, in the short to medium term many women in the developing world will continue to give birth without the supervision of a SBA. Thus, alongside striving for progress in improving access to SBAs, it has been argued that measures must be targeted at those women who will not be covered by these interventions [15–18]. The aim of this work is to inform policy-makers and those planning health services as to the scale of unattended births that might be expected over the coming years, both for individual countries and at regional level.
In this paper we use data from existing sources to estimate the number of non-SBA births that will take place between 2011 and 2015 in sub-Saharan Africa and South Asia, both in rural and urban areas. Due to large variation in the level of skilled birth attendance between countries, the analysis is performed for each country individually and subsequently aggregated to form the regional estimates presented in the main body of text; individual country level estimates are given in additional file 1: country-level results. We consider six scenarios defined by assumptions regarding the annual increase in the proportion of SBA births (based on current trends and increasingly optimistic projections) and the projected number of births (high and low fertility estimates).
We note that our work is intended to raise key policy issues rather than act as an accurate forecasting model.