BACKGROUND: Research on the effectiveness of strategies to reduce maternal mortality is scarce. We aimed to assess the contribution of intervention strategies, such as skilled attendance at birth, to the recorded reduction in maternal mortality in Matlab, Bangladesh. We examined and compared trends in maternal mortality in two adjacent areas over 30 years, by separate analyses of causes of death, underlying sociodemographic determinants, and areas and time periods in which interventions differed. METHODS: We analysed survey data that was routinely collected between 1976 and 2005 for about 200 000 inhabitants of Matlab, in Bangladesh, in adjacent areas served by either the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) or by the government. We used logistic regression to assess time trends in maternal mortality. We separately analysed deaths due to direct obstetric causes, abortion-related causes, and other causes. FINDINGS: Maternal mortality fell by 68% in the ICDDR,B service area and by 54% in the government service area over 30 years. Maternal mortality remained stable between 1976 and 1989 (crude annual OR 1.00 [0.98-1.01]) but decreased substantially after 1989 (OR 0.95 [0.93-0.97]). The speed of decline was faster after the skilled-attendance strategy was introduced in the ICDDR,B service area in 1990 (p=0.09). Abortion-related mortality fell sharply from 1990 onwards (OR 0.91 [0.86-0.95]). Educational differentials for mortality were substantial; the OR for more than 8 years of schooling compared with no schooling was 0.30 (0.21-0.44) for maternal mortality and 0.09 (0.02-0.37) for abortion mortality. INTERPRETATION: The fall in maternal mortality over 30 years occurred despite a low uptake of skilled attendance at birth. Part of the decline was due to a fall in abortion-related deaths and better access to emergency obstetric care; midwives might also have contributed by facilitating access to emergency care. Investment in midwives, emergency obstetric care, and safe pregnancy termination by manual vacuum aspiration have clearly been important. However, additional policies, such as those that bring about expansion of female education, better financial access for the poor, and poverty reduction, are essential to sustain the successes achieved to date.