Inequalities in maternal health

Maternal health is important because it sets the scene, not only for survival and subsequent health of the infant, but also for the woman herself. The traditional measurement of maternal health is the maternal mortality ratio. Gross inequalities exist in the maternal mortality ratio between developed and developing countries, and the gap is not closing. The maternal mortality ratio in developed countries is about nine in 100 000 births; in sub-Saharan Africa maternal death is over 100 times more common, and the context is different from that seen in developed countries.1

In the linked study (doi:10.1136/bmj.b542), Knight and colleagues use the United Kingdom obstetric surveillance system (UKOSS) to assess another aspect of maternal health—severe maternal morbidity. The study shows that severe maternal morbidity is significantly more common in non-white women than in white women in the UK, particularly those in black African and Caribbean ethnic groups. It also shows that ethnicity is a marker for poor maternal outcomes, not just for an increased likelihood of maternal death.2

Studying severe maternal morbidity improves our capacity to understand differences in maternal health beyond mortality, because the event rates are as much as 100 times higher than for maternal death in developed countries like the UK.3 This allows a more robust analysis and better general application of the policy implications. In addition, the causes of severe maternal morbidity may not be the same as those of maternal death.4 For these reasons, studying severe maternal morbidity allows us to expand our understanding of inequalities in maternal health.

Much is unclear about the association between ethnicity and poor maternal outcomes. This is compounded by the inconsistent use of terms such as race, ethnicity, and immigrant status. Most epidemiological research fails to define these terms or uses them interchangeably.5 Ethnicity is a social construct that should be self identified and consists of a range of features including language, race, birthplace, religion, and culture.6

One unresolved question is whether ethnicity itself is directly relevant to poor maternal outcomes, or whether it is a surrogate marker for a constellation of factors like low socioeconomic status, low level of education, and poor nutrition. It is a blunt marker when each ethnic grouping is so diverse. Despite the difficulties associated with the variable use of the terms, however, race, ethnicity, and immigrant status have consistently been associated with an increased likelihood for poor maternal outcomes, and they remain valuable epidemiological variables.7 Each term offers discrete information, with potentially different targeted actions. For example, consider two pregnant women whose ethnicity has been classified as “black African.” One was born, raised, and educated in the UK, and one arrived as a refugee two years ago. The second woman is more likely to have undiagnosed medical disorders like rheumatic heart disease, or to have been exposed to such a disorder, and she brings a higher risk status into pregnancy than her UK born counterpart. Newly immigrant women should have a full medical examination before pregnancy or early in pregnancy to identify such underlying diseases or risk factors.8

When tackling inequalities in maternal health in developed countries we need to raise concern for a group of women who, under traditional descriptors, are not considered to be at risk of poor health outcomes. These are the well educated, generally healthy, often more privileged women who choose to delay childbearing beyond the age of 35 years. This delay results in an array of changing reproductive characteristics, including a greater tendency to develop hypertensive and cardiovascular disorders, compounded by an increased frequency of multiple births and increased use of assisted conception. The combined effect of this social change is a group of women who unexpectedly carry a disproportionate burden of poor maternal outcome related to childbirth, even though they are not socially disadvantaged. The additional burden placed on the health of these women needs further investigation because women over 40 are up to eight times more likely to have a pregnancy related death than those in their early 20s.9 For this group of women, improving access to maternity services is not the solution. However, defining and communicating the risk of delaying childbirth for society may speed policy movements that could support earlier childbearing, such as paid maternity leave and flexible arrangements for return to work.

The UK is the world leader in the systematic examination and review of maternal deaths and has pioneered another world class process in UKOSS for the study of rare conditions in pregnancy. But even in the UK, limitations in the data collected restrict the meaningful interpretation of inequalities in health outcomes. For example, country of birth, main language spoken at home, socioeconomic status, and years in the UK are recommended as supplementary variables to race and ethnicity to help understand the influence of ethnicity on poor maternal health.10 Databases in the UK and in other developed countries could be improved by the routine collection of these variables for all childbearing women. Accurate, well defined data are necessary to improve our understanding of maternal health inequalities and to develop targeted policy and intervention or support strategies.