Why is a csection riskier than a natural delivery?

It is not! A small excess risk of maternal mortality is associated with modern c-sections (range 1:10, 000 to 1:100, 000), while the fetal life is more at risk with vaginal delivery (1:1, 000-1/10, 000). When all post-cesarean women have prophylaxis for clots and have no more than two cesarean sections, one can confidently state that c-sections are safer for modern maternal-fetal pairs than vaginal deliveries.