Maternal moality rate is calculated by

Maternal Moality Ratio (MMR) : Maternal deaths expressed as per 100,000 live bihs, where a 'maternal death' is defines as 'death of a woman while pregnant or during delivery or within 42 days (6 weeks) of termination of Pregnancy, irrespective of duration or site or pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes Maternal deaths expressed as per 100,000 live bihs (earlier it was expressed per 1000 live bihs but that yielded fractions like 4.08 maternal deaths per 1000 LB; so denominator was extrapolated to 100,000 to make MMR value more sensible MMR = No. Of Maternal deaths in a given year / Total no. Of live bihs in the same year x 100,000 Ref: Park 25th edition Pgno : 593