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Maternal mortality

Published:August 08, 2011DOI:https://doi.org/10.1016/j.ajog.2011.07.045
      The reduction in maternal deaths over the last 100 years in high-income countries is one of the greatest achievements of modern medicine, but one that, in recent years, seems to have been almost forgotten. In a walk through nearly any old cemetery, one finds the grave markers of large numbers of young women, many of whom died in childbirth. The statistics confirm these observations. Around 1900, depending on the country, between 300 and 1000 women per 100,000 of those who gave birth (0.3% to nearly 1%) died of the pregnancy.
      • Loudon I.
      Maternal mortality in the past and its relevance to developing countries today.
      • Loudon I.
      Death in childbirth: an international study of maternal care and maternal mortality 1800-1950.
      • O'Dowd M.J.
      • Philipp E.E.
      The history of obstetrics and gynaecology.
      In 1900, the maternal mortality rate in the United States was approximately 850 per 100,000 births. In contrast, today in most high-income countries, approximately 10-20 per 100,000 women die in conjunction with childbirth, which is almost a 99% reduction.
      • Ronsmans C.A.
      • Graham W.J.
      Maternal mortality: who, where, when and why.
      Based on data from high-income countries where historic data are available and reliable, it appears that, although slow improvements in maternal mortality rates had occurred in some areas before 1930, the decline in nearly all countries became precipitous beginning at approximately 1935 and continued in a linear fashion until approximately 1970 (Figure).
      • Loudon I.
      Maternal mortality in the past and its relevance to developing countries today.
      • Loudon I.
      Death in childbirth: an international study of maternal care and maternal mortality 1800-1950.
      • O'Dowd M.J.
      • Philipp E.E.
      The history of obstetrics and gynaecology.
      The declines then slowed, with little or no improvements since that time. Interestingly, despite large differences in maternal mortality rates between countries in 1935, by 1960 nearly all high-income country maternal mortality rates converged to a rate of approximately 60 per 100,000, and continued to decline until the 1970s and 1980s, at which time the rates were all in the range of 10-20 deaths per 100,000 births.
      See related article, page 331
      Figure thumbnail gr1
      FIGUREMaternal mortality rates from the United States (US), United Kingdom (UK), and Sweden, 1900-2000
      Data were adapted from Loudon,
      • Loudon I.
      Maternal mortality in the past and its relevance to developing countries today.
      Loudon,
      • Loudon I.
      Death in childbirth: an international study of maternal care and maternal mortality 1800-1950.
      O'Dowd,
      • O'Dowd M.J.
      • Philipp E.E.
      The history of obstetrics and gynaecology.
      and Ronsmans.
      • Ronsmans C.A.
      • Graham W.J.
      Maternal mortality: who, where, when and why.
      Goldenberg. Maternal mortality. Am J Obstet Gynecol 2011.
      There are several potential explanations for the large differences in maternal mortality rates before 1935 between the United States and some of the European countries. These explanations include differences in the definition of a pregnancy-related maternal death, the underlying strength of the public health system, and the extensive use of trained midwives in several European countries. Probably more important was the adoption of a number of obstetric practices in the United States that included the use of chloroform and other anesthetics for delivery, the elective use of internal podalic version, elective manual dilation of the cervix, elective manual removal of the placenta, and the common use of prophylactic mid forceps and even high forceps for delivery. Cessation of these and other dangerous practices likely contributed to a portion of the decline in the maternal mortality rate in the United States.
      • Loudon I.
      Death in childbirth: an international study of maternal care and maternal mortality 1800-1950.
      One can better understand the reduction in maternal mortality rates in all locations if one focuses on the major causes of maternal death and the interventions that were used to reduce deaths from those causes.
      • Hogberg U.
      • Wall S.
      Secular trends in maternal mortality in Sweden from 1750 to 1980.
      Deaths from sepsis, for example, could have been reduced by the prevention of infection through the increased use of sterile fields for delivery and hand washing and the use of sterile gloves. However, the timing of the steep decline in infection-related maternal deaths is consistent with a major role for antibiotics in the treatment of those women who became infected. In most countries, sulfonamides were introduced into clinical practice at approximately 1939 and penicillin in the 1940s; much of the initial rapid decline in maternal deaths is attributed to their use. Thus, together with aseptic techniques, the use of antibiotics appears to be the most important contributor to the dramatic decrease in maternal mortality rates.
      Hemorrhage, which often is complicated by preexisting anemia, is a major killer of pregnant women.
      • Ronsmans C.A.
      • Graham W.J.
      Maternal mortality: who, where, when and why.
      The hemorrhage can occur in the antepartum period because of a placental abruption or a placenta previa or uterine rupture during labor or in the postpartum period because of uterine atony, retained placenta, laceration of the cervix or vagina, and ectopic pregnancy or incomplete spontaneous or therapeutic abortion. In the 1930s and 1940s, cesarean section delivery for abruption and placenta previa became standard practice after a study that demonstrated that cases that were treated with cesarean section delivery had a maternal mortality rate of <2%. For the treatment of a uterine atony, ergometrine became available between 1935 and 1940, and oxytocin became available at approximately 1960. Probably more important, for all causes of bleeding, blood transfusion first became widely available in the 1940s and 1950s.
      • Learoyd P.
      A short history of blood transfusion.
      Until the last half century, eclampsia was a major killer of pregnant women in the United States and in every other country that has historic data about the causes of maternal death. However, since the 1940s, in all high-income countries, there have been substantial reductions in both the incidence of eclampsia and its case fatality rate.
      • Goldenberg R.L.
      • McClure E.M.
      • MacGuire E.R.
      • Kamath B.
      • Jobe A.
      MANDATE Team
      The historical reduction in hypertension related maternal mortality in developed countries: lessons learned for developing countries.
      Widespread introduction of prenatal care in many countries that began in the 1930s and 1940s with an emphasis on preeclampsia detection (blood pressure and proteinuria testing), especially late in pregnancy, and hospital care that included timely induction of labor and cesarean delivery for women with severe preeclampsia or eclampsia, were the crucial elements both in the reduction of the progression of preeclampsia to eclampsia and from eclampsia to death.
      • Goldenberg R.L.
      • McClure E.M.
      • MacGuire E.R.
      • Kamath B.
      • Jobe A.
      MANDATE Team
      The historical reduction in hypertension related maternal mortality in developed countries: lessons learned for developing countries.
      In most countries, the widespread use of magnesium sulfate for the prevention or treatment of seizures was not common until the 1960s or later, after the major reductions in eclampsia-related maternal mortality rates were achieved.
      Prolonged and obstructed labor, which often is complicated by intrauterine infection and maternal sepsis and at times uterine rupture, was another important cause of maternal death. As more women had access to hospital care and surgical delivery, again that began in the 1930s and 1940s, death from this condition virtually disappeared. With the availability of antibiotics and blood transfusion, the most important complications of surgical procedures that were aimed at reducing maternal deaths (cesarean delivery, tubal excision for ectopic pregnancy, hysterectomy, and repairs of uterine, cervical, and vaginal lacerations) could be treated effectively. Thus, between 1935 and 1960, many of the interventions that could prevent or treat each of the most important causes of maternal death were introduced and increasingly became available. Widespread use of prenatal care with repetitive testing for preeclampsia, the increasing use of hospitals for delivery, the availability of inductions of labor, cesarean section deliveries, antibiotics, and blood transfusions were the crucial elements that resulted in the decrease in maternal mortality rates.
      Beginning in the 1930s and 1940s and coincident with the reductions that were seen in maternal deaths in the United States and elsewhere, maternal mortality audits were performed at hospitals by medical societies and by various official groups who evaluated maternal deaths within specific geographic boundaries.
      • Grimes D.A.
      • Cates W.
      The impact of state maternal mortality study committees on maternal deaths in the United States.
      • Marmol J.G.
      • Scriggins A.L.
      • Vollman R.F.
      History of the maternal mortality study committees in the United States.
      Feedback from these audits is thought by many to have resulted in substantial reductions of inappropriate obstetric practices such as those mentioned earlier and the adoption of effective prevention and treatment practices for the conditions that kill mothers. However, by the 1980s and 1990s, likely because of the relative scarcity of maternal deaths and perhaps because of malpractice concerns in the United States, many of the committees that reviewed maternal deaths were disbanded. Related or not, since that time, the US maternal death rates appear to have increased.
      • McKay A.P.
      • Berg C.J.
      • Liu X.
      • Duran C.
      • Hoyert D.L.
      Changes in pregnancy mortality ascertainment United States, 1999-2005.
      In this issue of the Journal, Farquhar et al
      • Farquhar C.
      • Sadler L.
      • Masson V.
      • Bohm G.
      • Haslam A.
      Beyond the numbers: classifying contributory factors and potentially avoidable maternal deaths in New Zealand, 2006–2009.
      present a system that classifies maternal deaths by cause, by contributing circumstances, and by potential avoidance. Thirty-five percent of the deaths in New Zealand that occurred over a 4-year period were found potentially to be avoidable, which are results that are similar to other published studies that have originated from high-income countries. Knowledge regarding the proportion of deaths that are avoidable provides a target for improvement; knowledge regarding the cause and contributing conditions allows providers and health system administrators to take appropriate actions to reduce maternal deaths. The study by Farquhar et al supports the case that has been made by others for a return in the United States to universal formalized maternal mortality audits that are confidential in nature and performed locally, with feedback that is aimed at improving care. Review of all maternal deaths with feedback is an important step if we are to eliminate all avoidable maternal deaths.
      We should add that worldwide, 99% of maternal deaths occur in low- and middle-income countries with numbers 10- to 100-fold greater than those seen in counties like the United States and New Zealand.
      • Ronsmans C.A.
      • Graham W.J.
      Maternal mortality: who, where, when and why.
      Despite these very large differences, the principles set forth in the paper by Farquhar et al remain the same. To reduce maternal deaths effectively in any location, the circumstances under which pregnant women are dying and the proportion of those deaths that are avoidable should be known. Only with such data can programs be instituted that effectively reduce maternal mortality rates.

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