We assess technical efficiency (TE) level for Mexican Ministry of Health (MoH) primary care units. Assessment was focused on the production of adequate maternal health services defined as the coverage level of women who received timely and frequent antenatal care, and institutional and medical care during childbirth. We conducted a longitudinal analysis of administrative and socio-demographic information concerning 233 health jurisdictions for the period 2008-15. Crude TE was calculated using window data envelopment analysis (Windows-DEA). Empirical analysis included the description of several factors affecting the production of maternal health services, including the heterogeneity and trends assessment of TE among health jurisdictions. We estimated a pooled regression model with robust standard errors to identify correlates of TE and estimated adjusted performance scores. Results indicate that while the production of adequate maternal-health services and TE in health jurisdictions proved insufficient, they rose by 22% (from 40.9% to 49.8%) and 14% (from 54.3% to 62%), respectively, over time. Furthermore, variance in efficiency among production units diminished and persistent regularities were observed. Performance was highest in the Northern as opposed to the Southern and Southeastern health jurisdictions, but lowest in the most marginalized zones of the country marked by economic inequality and the presence of indigenous populations. The Mexican Health System has reached a paradoxical situation: the steady escalation of financial resources in the public health subsystem over the past 15 years has yielded sub-optimal results as regards coverage for essential maternal health interventions among the poorest. Mexican government must put in place a set of measures to guarantee efficiency in the system's performance without affecting equity gains. This necessarily involves reconsidering, and where necessary replacing, the criteria behind the allocation and distribution of resources, as well as the mechanisms for controlling how resources are used and accountability is fulfilled.