Reproductive Epidemiology

Maternal Mortality

Maternal mortality is defined by the World Health Organization (WHO) as the death of a woman during pregnancy or within 6 weeks of termination of pregnancy from any cause related to or aggravated by the pregnancy or its management. The causes of the death can be categorized into direct and indirect obstetric deaths. Direct obstetric death is caused by complications of pregnancy, delivery, or the puerperium (the period immediately after childbirth and lasting about 6 weeks, during which the mother's body returns to its prepregnant condition). The five major causes of direct obstetric deaths worldwide are hemorrhage, complications of unsafe abortion, eclampsia, infection, and obstructed labor. Indirect obstetric death results from previously existing conditions or conditions physiologically aggravated by the pregnancy. Common examples of such conditions are malaria, anemia, HIV/AIDS, and cardiovascular disease. Nonobstetric deaths include other deaths during but not caused by the pregnancy, such as those caused by accidents or by intentional acts not caused directly by the pregnancy (e.g., murder). According to a report jointly prepared by the WHO, UNICEF (United Nations Children's Fund), and UNFPA (United Nations Population Fund), there were 529,000 maternal deaths in 2000, of which more than 99.5% occurred in developing regions. Three commonly used measures related to maternal mortality are the maternal mortality rate, maternal mortality ratio, and lifetime risk of maternal death.

Infant Mortality

The infant mortality rate (IMR) is defined as the rate per 1,000 live births at which babies less than 1 year of age die. It is calculated by dividing the number of infant deaths in a given year by the number of live births in the same given year. The IMR is often used to compare the general health and wellbeing of populations within and between countries and is sometimes considered a proxy or indicator of the quality of health care available to the relevant population. Comparing different countries’ IMRs can sometimes be difficult when different definitions of ‘live birth’ are employed. For example, the WHO defines a live birth as any born human being who demonstrates independent signs of life, including breathing, voluntary muscle movement, or heartbeat. Some European states and Japan, however, only count as live births those in which an infant breathes at birth, thereby causing their IMRs to be somewhat lower and their perinatal mortality rates to be somewhat higher than in settings using other definitions. Excluding high-risk infants from the denominator or numerator in reported IMRs also makes comparing rates problematic.

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