Effects of Maternal Immunization on Birth Weight in Rural Cameroon
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Effects of Maternal Immunization on Birth Weight in Rural Cameroon Mbu Daniel Tambi Research Paper 413 RICAN ECONOMIC RESEARCH CONSORTIUM RESEARCH ECONOMIC RICAN AF SORTIUM POUR LA RECHERCHE ÉCONOMIQUE EN AFRIQUE EN ÉCONOMIQUE LA RECHERCHE POUR SORTIUM CON Bringing Rigour and Evidence to Economic Policy Making in Africa Effects of Maternal Immunization on Birth Weight in Rural Cameroon By Mbu Daniel Tambi Department of Agricultural Economics University of Dschang, Cameroon AERC Research Paper 413 African Economic Research Consortium, Nairobi January 2021 THIS RESEARCH STUDY was supported by a grant from the African Economic Research Consortium. The findings, opinions and recommendations are, however, those of the author and do not necessarily reflect the views of the Consortium, its individual members or the AERC Secretariat. Published by: The African Economic Research Consortium P.O. Box 62882 - City Square Nairobi 00200, Kenya ISBN 978-9966-61-108-6 © 2021, African Economic Research Consortium. Contents List of tables Abstract 1. Background 1 2. Literature Review 5 3. Methodology 8 4. Empirical Results 16 5. Conclusion: Summary and Policy Implication 29 Notes 30 References 31 List of tables 1. Immunization profile – Cameroon (%) 2 2. Weighted sample statistics of birth weight (BW) and no 18 birth weight children 3. Sample statistics of place of residence and economic 20 status of households 4. Reduced-form parameter estimates for tetanus immunization 23 (= 1 if immunized, 0 otherwise) 5. Parameter estimate of birth weight production function 25 6. Parameter Estimate of Birth Weight Production Function: 27 Place of Residence and Economic Status of Households Abstract This study investigated the effects of tetanus immunization on birth weight in rural Cameroon. Specifically, the study sought to: examine the determinants of mother’s immunization in Cameroon; assess the impact of mother tetanus immunization on child health production; examine how birth weight production function can be estimated by area of residence and household income; and propose policy implications on the basis of the findings. To tackle these objectives, the study used the ordinary least square (OLS) model. Empirical results were based on pooled data from the 2004 and 2011 demographic and health surveys (DHS) collected by the government’s statistics office. The results showed that maternal immunization during pregnancy was associated positively with birth weight, overall in rural and urban areas, and among poor and non-poor households. Other variables that were significantly associated with birth weight in rural Cameroon were: mother’s education in years of schooling, mother’s age, father’s age, first twin birth, male child birth, non- poor, interaction of mother’s and father’s education and urban household residence. These results have implications for addressing child health concerns in the ongoing process of growth, employment and poverty reduction in terms of improving access to antenatal care and family planning in rural Cameroon. Keywords: Effects, Maternal Immunization, Birth Weight, Ordinary Least Square, Rural Cameroon EFFECTS OF MATERNAL IMMUNIZATION ON BIRTH WEIGHT IN RURAL CAMEROON 1 1. Background Child health has long been a major focus of the literature on human capital production function in development economics, where production functions have been estimated for child height given age, weight given age, weight given height, birth weight, gestation age and diarrhoeal incidence (Rosenzweig and Schultz, 1983). Health has generally been accepted as an important determinant of human capital along with education and hence factor productivity (Wilhelmson and Gerdtham, 2006). In this context, health provides utility not only directly but also indirectly as it is a key input into many production processes (Grossman, 1972). Health conditions in utero have consequences for later life cycles (Victoria et al., 2008; Mwabu, 2009). According to Mwabu (2009), previous studies have shown strong correlations between low birth weight and infant mortality, high blood pressure, cerebral palsy, deafness and behavioural problems in adult life (Case et al., 2005). This implies that birth weight does not only affect child health but also have implications for health in adulthood where productivity can be strongly affected. In Cameroon2, the general health of the population has deteriorated considerably since the early 1990s. The mortality rate increased by 12% between 1991 and 1998, the chronic malnutrition rate for children aged 12 to 23 months old also rose from 23% to 29% and the rate of delivery attended by qualified practitioners (doctors and nurses) declined by 5% during the same period. Moreover, between 1991 and 2002, the rate of HIV/AIDS infection within the sexually active population rose alarmingly from 2% to 11.8% (Government of Cameroon, 2003). As a tool for improving child and maternal healthcare by 2008, the Government of Cameroon implemented a 5-year action plan in the Extended Program for Immunization (EPI), incorporating the following: (i) mobilizing additional resources for immunization, independence and introducing new vaccines; (ii) training/retraining staff and rehabilitating/renewing equipment; (iii) developing communication materials to promote behavioural changes; (iv) outsourcing programme implementation responsibilities to health districts; and (v) ensuring programme monitoring and evaluation activities (Government of Cameroon, 2011). 1 2 RESEARCH PAPER 413 Table 1: Immunization profile—Cameroon (%) Vaccine 1990 2000 2008 2009 2010 2011 2013 Vaccine for children (aged 0 to 5 years) Bacille Calmette-Guerin (BCG) 52 69 86 79 83 80 83 DTC3 = DTC+ HepB-reference 36 53 84 80 84 82 86 antigen (DTC3) Measles (VAR) - 49 77 72 79 76 68 Poliomyelitis (VPO) 34 49 82 79 83 80 89 Yellow fever (VAA) - - 77 72 79 75 61 Diphtheria-tetanus-pertussis - 54 93 88 92 90 91 (DTP1) Infection due to pneuoccocus - 48 88 84 78 80 79 (Pneumo) Avitaminosis (VIT.A) 44 62 84 81 90 87 92 Vaccine for mothers Anti-tetanus for expectant mothers 82 79 65 72 83 80 85 (VAT2+) Tetanus toxoid (TT2+) 12 40 76 73 74 69 91 Source: WHO-UNICEF coverage estimates (2012 NOT IN REF LIST) and MPH (2014) The focus of this study was maternal immunization using tetanus toxoid (TT2+). The evolution of this vaccine among women has been irregular, beginning in 1990 (12%), to 69% in 2011 with its peak in 2008 at 76%. Whereas vaccinating pregnant women may protect young infants from infectious causes of mortality by passive immunization and by reduced transmission to the neonate from mother (Klaugman, 2014), as noted by WHO (2006), the effectiveness of a vaccine programme largely depends on: (1) the proportion of susceptible individuals who have access to immunization services; (2) the vaccine failure rate (i.e., the proportion of individuals properly vaccinated but who fail to develop a protective response); (3) the vaccine efficacy (i.e., the proportion of individuals who may be expected to develop a protective response to the vaccine under optimal field conditions never 100%); (4) the effective procedures for preserving the vaccine at optimal temperature during transit; (5) the training of vaccinators to ensure proper administration of the vaccine; (6) the attitude of the vaccination staff; (7) the knowledge and attitudes of the population; and (8) the proportion of the population willing to submit to the vaccination schedule. Further, the first time this vaccine was introduced, it caused many allergic reactions in the mothers and foetuses that created fear on the part of the women and so some became sceptical while others still took the vaccine because of the vaccination campaigns. Generally, vaccines can occasionally induce allergic reactions, ranging from mild to severe anaphylactic responses. Adverse responses may be due to components of the vaccine, for example, residues of materials used to prepare the vaccines, preservatives, etc. Specific recommendations with regard to allergic reactions are provided by the producers of each vaccine and should be heeded. EFFECTS OF MATERNAL IMMUNIZATION ON BIRTH WEIGHT IN RURAL CAMEROON 3 Excessive interpretation of contraindications (e.g., non-febrile mild acute illnesses, or mild illnesses with temperature elevations of 101°F or less) results in reduced uptake of vaccine. While severe illness should be viewed as contra-indicative of immunization, mild acute illness with or without low grade fever, current microbial therapy and the convalescent phase of an illness are not reasons to avoid or delay vaccination (WHO, 2006). Following the Government of Cameroon (2011) and the respective demographic and health surveys (DHS), the trend and coverage of tetanus immunization have not been uniform, varying as follows: 71% in 1991, 82% in 1998, 79% in 2004 and 51% in 2011. The role of tetanus vaccination is to reduce the risk of the foetus contracting tetanus during birth, an outcome which motivates the mother to invest in better nutrition and behaviours that enhance foetal growth and, therefore, reduce the risk of her infant dying due to low birth weight. The central argument is not that tetanus vaccination directly increases birth weight, but that it is strongly correlated with healthcare consumption and behaviours that increase birth weight (Bategeka et al., 2009). Despite these efforts, child healthcare literature for Cameroon is lacking (Ako et al., 2008). Training in reproductive health overall has not been a priority in the health sector. Current