A reassessment of global antenatal care coverage for improving maternal health using sub-Saharan Africa as a case study

Background Antenatal period is an opportunity for reaching pregnant women with vital interventions. In fact, antenatal care (ANC) coverage was an indicator for assessing progress towards the Millennium Development Goals. This paper applies a novel index of service coverage using ANC, which accounts for every ANC visit. An index of service coverage gap is also proposed. These indices are additively decomposable by population groups and they are sensitive to the receipt of more ANC visits below a defined threshold. These indices have also been generalised to account for the quality of services. Methods Data from recent rounds of the Demographic and Health Survey (DHS) are used to reassess ANC service coverage in 35 sub-Saharan African countries. An index of ANC coverage was estimated. These countries were ranked, and their ranks are compared with those based on attaining at least four ANC visits (ANC4+). Findings The index of ANC coverage reflected the level of service coverage in countries. Further, disparities exist in country ranking as some countries, e.g. Cameroon, Benin Republic and Nigeria are ranked better using the ANC4+ indicator but poorly using the proposed index. Also, Rwanda and Malawi are ranked better using the proposed index. Conclusion The proposed ANC index allows for the assessment of progressive realisation, rooted in the move towards universal health coverage. In fact, the index reflects progress that countries make in increasing service coverage. This is because every ANC visit counts. Beyond ANC coverage, the proposed index is applicable to assessing service coverage generally including quality education.

( ) by a permutation, and the recommended minimum number of ANC visits ( ) remains unchanged, then ( ) = ( ). This axiom is relevant as it treats all pregnant women equally. Thus, the ANC coverage (or coverage gap) index is estimated based on only information directly related to ANC visits and does not require any other characteristics of the women.

Replication invariance axiom (or population principle)
Holding all else constant, if a new distribution ( ) is obtained by replication of the original distribution ( ) and the recommended minimum number of ANC visits remains unchanged, then = and by implication, = .

Focus axiom
Holding all else constant, when a pregnant woman that has attained at least the recommended minimum number of ANC visits (e.g. at least four ANC visits) reports more ANC visits, will remain unchanged. This property means that any further ANC visits among those that have attained the recommended minimum number of ANC visits ( ) would have no effect on the measure of ANC coverage or coverage gap. It is only any increase or decrease in the number of ANC visits 2 among those that have not attained the minimum number of visits that has an impact on and .

Scale invariance axiom
Holding all else constant, if all ANC visits (including the recommended minimum number of ANC visits) are multiplied by the same proportion > 0, then will remain unchanged.

Monotonicity axiom
Holding all else constant, when a pregnant woman with less than the recommended minimum number of ANC visits (e.g. four ANC visits) attains at least one more ANC visit, the ANC coverage index ( ) improves while the ANC coverage gap ( ) reduces.

Transfer axiom
Because it is not literally possible to transfer ANC visits from one woman to another, a modification of the axiom is discussed here. This is also consistent with discussions regarding non-monetary dimensions of poverty. This means that increasing the number of women with fewer ANC visits will increase (by monotonicity) but the increment will be less than that which will result from increasing the number of pregnant women with higher ANC visits. These ANC visits should all be less than the recommended minimum number of visits ( ). This axiom implies that the impact of fewer visits on is less than the impact of more visits if we are focusing on women with less than the recommended minimum number of ANC visits.

Normalisation axiom
This is a trivial axiom which simply means that = 1 ( = 0) if all women aged 15-49 with a live birth within a given period had attained the recommended minimum number of ANC visits. In the 3 case of four ANC visits (as a bare minimum), this means that 100% of the women had attained at least four ANC visits within the reference period.

Sub-group decomposition (additive)
Holding all else constant, overall ANC coverage index ( ) can be obtained as the weighted average of ANC coverage of all mutually exclusive groups, where the weights are the relative shares of the groups in the total population. E.g., if two mutually exclusive groups ( and ) are formed with their respective ANC coverage given as and and sub-populations and where + = , then is additively decomposable as = 1 ( ( ) + ( )). Generally, this can be extended to any arbitrary number of groups ( ≥ 2) such that = 1 ∑ ( ).