Malaria Research and Treatment

Volume 2014 (2014), Article ID 694863, 7 pages

http://dx.doi.org/10.1155/2014/694863

Research Article

The Effect of Mass Media Campaign on the Use of Insecticide-Treated Bed Nets among Pregnant Women in Nigeria

A. Ankomah,¹ S. B. Adebayo,² E. D. Arogundade,³ J. Anyanti,⁴ E. Nwokolo,⁵ U. Inyang,⁶ Oladipupo B. Ipadeola,⁶ and M. Meremiku⁷

¹Department of Population, Family and Reproductive Health, School of Public Health, University of Ghana, P.O. Box LG 25, Legon, Accra, Ghana

²Planning, Research and Statistics Directorate, National Agency for Food and Drug Administration and Control, PMB 5023, Wuse, Abuja, Nigeria

³PLAN-Health Project, Management Sciences for Health, P.O. Box 240, Kubwa, Abuja, Nigeria

⁴Technical Services Directorate, Society for Family Health, PMB 5116, Wuse, Abuja, Nigeria

⁵Society for Family Health, PMB 5116, Wuse, Abuja, Nigeria

⁶Malaria Action Program for States, PMB 44, Abuja, Nigeria

⁷University of Calabar, PMB 1115, Calabar, Nigeria

Received 30 September 2013; Revised 6 February 2014; Accepted 13 February 2014; Published 20 March 2014

Academic Editor: Theonest K. Mutabingwa

Copyright © 2014 A. Ankomah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Background. Malaria during pregnancy is a major public health problem in Nigeria especially in malaria-endemic areas. It increases the risk of low birth weight and child/maternal morbidity/mortality. This paper addresses the impact of radio campaigns on the use of insecticide-treated bed nets among pregnant women in Nigeria. Methods. A total of 2,348 pregnant women were interviewed during the survey across 21 of Nigeria’s 36 states. Respondents were selected through a multistage sampling technique. Analysis was based on multivariate logistic regression. Results. Respondents who knew that sleeping under ITN prevents malaria were 3.2 times more likely to sleep under net (OR: 3.15; 95% CI: 2.28 to 4.33; ). Those who listened to radio are also about 1.6 times more likely to use ITN (OR: 1.56; 95% CI: 1.07 to 2.28; ), while respondents who had heard of a specific sponsored radio campaign on ITN are 1.53 times more likely to use a bed net (). Conclusion. Pregnant women who listened to mass media campaigns were more likely to adopt strategies to protect themselves from malaria. Therefore, behavior change communication messages that are aimed at promoting net use and antenatal attendance are necessary in combating malaria.

1. Background

Malaria during pregnancy is a major public health problem; it increases the risk of low birth weight (LBW) (<2500 g) and child morbidity and mortality during the first year of life by inducing intrauterine growth retardation, prematurity, infant anaemia, and maternal anaemia [1–3]. It is estimated that over 30 million women living in malaria-endemic parts of Africa become pregnant every year [4]. Malaria in pregnancy is responsible for 11% of maternal deaths in Nigeria [5]. In areas where malaria is endemic, 20–40% of all babies born may have low birth weight [6]. Malaria in pregnancy is a priority area in the Global Roll Back Malaria (RBM) strategy. In 2000, the World Health Organization recommended a package of interventions to prevent malaria during pregnancy. This package includes the promotion of insecticide-treated bed nets (ITNs), intermittent preventive treatment in pregnancy (IPT), and effective case management of malarial illness [7]. The strategy also promotes the integration of malaria prevention into the safe motherhood package. Therefore, one of the strategies of the Nigerian National Strategic Plan for Malaria Control is to create awareness on prevention of malaria in pregnancy through the use of ITNs, among others.

There has been a massive effort to ensure availability of ITNs in every household in Nigeria as part of the scaling up for impact (SUFI) which endeavours to ensure universal access to long lasting insecticide-treated nets (LLINs). During distribution campaigns, LLINs are provided free to household members such that every household has at least two nets. In addition, nets are provided at highly subsidized rates through social marketing in health facilities and drug stores for ease of access to pregnant women and women with children less than five years. The cost-effectiveness of ITNs relative to other forms of malaria prevention and treatment also makes it a better option for malaria prevention especially among residents of rural communities, people with poor access to health facilities, and people with low socioeconomic status [8–10]. The risk of malaria in pregnancy has been reported in several countries in sub-Saharan Africa including Uganda [11], Malawi [12], Tanzania [13], and Ethiopia [14].

In a study among pregnant women in Lagos state, only 11.2% and 37.5% actually used ITNs in two study hospitals [15]. In some parts of Nigeria, use of bed nets among pregnant women is still low. In a study in northern Nigeria, 73% of respondents have never used ITN before because of lack of awareness [16]. In another study in Ibadan, southwest Nigeria, only 20.9% of pregnant women use ITNs [17].

To promote use and uptake of these malaria prevention strategies, mass media campaigns have been initiated to sensitise the general public, particularly pregnant women, on the effectiveness and long term benefits of correct and consistent use of the ITNs during pregnancy. The mass media campaign messages were aired on national radio and television stations in English, Pidgin English, and the three main local languages in Nigeria. Also billboards with clear messages about the link between mosquitoes and malaria prevention were placed at strategic locations in major cities in Nigeria to further improve access to correct information. The messages on the billboards were reproduced into posters and handbills that were widely distributed across the country. This evaluation is focused only on the mass media campaign via the radio. Very few nationwide health interventions are evaluated. The aim of this paper is to assess the impact of exposure to these campaigns on uptake of the malaria prevention strategies in pregnancy.

2. Data and Methods

2.1. Study Area and Population

Twenty-one out of the 36 states in Nigeria including the Federal Capital Territory were visited for this study. All the states were implementing programmes that draw from the National Strategic Plan for Malaria Control which is based on the principles of Global Malaria Control strategy and Roll Back Malaria initiatives. This study was a cross-sectional and population-based survey. A systematic multistage sampling technique was used to select pregnant women resident in the eighteen Global Fund states and three other adjoining states. The first stage was the selection of localities/sites to form 20 clusters. All the localities in a state were arranged in their geographic order with their sizes attached. The projected population of the localities was considered as the measure of size. A cumulative measure of size was obtained and using a systematic sampling procedure, 20 clusters were allocated to the localities. Pregnant women within the selected households were identified and screened for eligibility. Data were collected by trained interviewers using validated questionnaires to obtain information on maternal and child health with focus on malaria control. Data from a total of 2,348 pregnant women who were interviewed were collated and analysed.

The dependant variable is based on the responses from respondents to the question on whether the respondent slept under an ITN the night prior to the study. All analyses were performed using SPSS 18.0 and conclusions are based on the 0.05 level of significance.

Structured questionnaires based on thematic areas were administered by trained interviewers. The questionnaire was validated and pilot tested before use. Interviewers were trained with a specific focus on all aspects of the interview process and questionnaires. The questionnaires were pretested to check for comprehensibility of questions as well as procedures for conducting interviews. The study questionnaires elicited information on key programme indicators and the various issues related to knowledge, behaviour, and practices related to prevention and treatment of malaria. The questionnaire also elicited information to determine if respondents listened regularly to the radio and if they listened to specific messages presented in radio broadcasts that focused on prevention of malaria. Approval was also received from the State Ministries of Health and leaders of each of the communities selected for the survey. Informed verbal consent was obtained from the heads of households and the respondents; those who declined consent were not interviewed. All selected caregivers and pregnant women were interviewed in their homes and confidentiality was assured. During data collection, quality control processes were implemented by supervisors to identify and correct problems while in the field.

Data were entered using the Census and Survey Processing System (CSPro) and were exported to, managed, and analysed using Statistical Package for the Social Sciences (SPSS 18.0). Frequency tables and cross tabulations were used to generate data tables and figures to present results in keeping with survey objectives and analysis plan. We employed a logistic regression technique [18–20] to explore influence of factors such as knowledge about ITN, causes of malaria, and correct ways of preventing malaria on the use of bed nets.

Specifically, we explored exposure to mass media campaigns in Nigeria under the auspices of the National Malaria Control Programme with emphasis on messages promoting the use of ITNs. We aimed to determine whether the use of ITNs could be attributed to exposure to this mass media campaign. All categorical variables were dummy-coded. We explored the influence of these determinants on the use of ITNs and later explored the influence of exposure to mass media on the use ITNs. A binary dependent variable was created for use or nonuse of ITNs and determinants, as well as exposure to media. Statistical significance was based on a value of 0.05. At an exploratory data analysis stage, several models were explored. Test of goodness-of-fit was based on Hosmer and Lemeshow test [21], with models with assumed to be good and to fit well to the data. In this study, exposure was measured as having listened to radio and having heard of the special media campaigns on the use of ITNs. We proposed the null hypothesis that there will be no relationship between personal media exposure and use of ITNs.

3. Variables

Table 1 presents the general characteristics of the pregnant women involved in the survey. The dependent and independent variables are described in the next section.

Table 1: Percentage distribution of the demographic characteristics of the respondents included in the survey.

Characteristics
Urban ()
Rural ()
Total ()

%

%

%

Age of respondent

    Below 26 years
331
31.1
505
39.3
836
35.6

    26 years and above
733
68.9
779
60.7
1512
64.4

Education

    None
137
12.9
316
24.6
453
19.3

    Qur’anic only
114
12.3
208
21.5
322
13.7

    Primary
210
22.7
326
33.7
536
22.8

    Secondary
466
50.3
369
31.8
835
35.6

    Higher
137
14.8
65
6.7
202
8.6

Geopolitical zones

    Northwest
197
18.5
260
20.2
457
19.4

    Northeast
184
17.3
268
20.9
452
19.3

    North-central
189
17.8
263
20.5
452
19.3

    Southwest
247
23.1
101
7.9
348
14.8

    Southeast
110
10.3
188
14.6
298
12.7

    South-south
137
12.9
204
15.9
341
14.5

Occupation

    Formal job
87
8.2
51
3.9
138
5.9

    Self-employed
366
34.4
387
30.2
753
32.0

    Housewives
397
37.3
481
37.5
878
37.4

    Others
248
22.3
331
29.3
579
24.7

ANC attendance

    Registered
618
58.1
630
49.1
1248
53.2

    Did not register
446
41.9
654
50.9
1100
46.8

Ownership of nets

    Yes
296
34.8
381
35.6
677
35.3

    No
557
65.3
1114
64.3
1671
64.7

Received IPT

    Yes
247
23.2
282
22
529
22.5

    No
817
76.8
1002
78
1819
77.5

3.1. Dependent Variable

The dependent variable is the use or nonuse of ITN the night immediately preceding the survey.

3.2. Independent

The key independent variables in this paper are geopolitical zones, residence, age, education, educational attainment, gestational stage of registration for antenatal care, knowledge about use of ITN, listenership to radio, exposure to campaigns on ITN, locality of residence (rural or urban), knowledge about modes of prevention of malaria, age of the respondents, and knowledge that mosquito bites are the main cause of malaria. All the independent variables were dummy-coded. For instance, five dummy variables were created for Nigeria’s six geopolitical zones (northeast, northwest, southeast, southwest, and south-south) with north-central being the reference category. For locality of residence, rural area was considered as reference category, and respondents below age of 20 were considered as reference category for respondents’ age. Education was an ordinal variable, with five possible responses regarding the highest level of education attained: no formal education, Qur’anic, primary, secondary, and postsecondary education.

4. Results

A total of 2,348 pregnant women were interviewed during the survey across the 21 states. Table 1 presents findings of the descriptive summary and sociodemographic characteristics of respondents. Overall, about a fifth of the respondents had never attended school. There is a substantial geographic variation with northeast having the highest proportion of respondents with no formal education. Respondents in age group 26 years and above constituted the largest proportion. About 37 percent of the respondents interviewed were housewives, 32 percent were self-employed, and only about 6 percent have a formal job (blue collar job). Unlike in the other geopolitical zones, a substantially larger proportion of the respondents were in urban areas than in rural areas.

Table 2 presents findings of the bivariate analyses of use of ITNs by selected characteristics. Knowledge of modes of preventing malaria, ownership of bed nets, knowledge that using an ITN prevents malaria, knowledge of dangers of malaria in pregnancy, and ANC attendance were all significantly associated with ITN use.

Table 2: Bivariate analysis showing percentage distribution of use of ITN according to selected sociodemographic characteristics.

Characteristics
Use of ITN

Yes ()
No ()
value

Value
%
Value
%

Locality

    Rural
126
11.8
938
88.2
0.141

    Urban
133
10.4
1151
89.6

Age of caregivers

    Below 26 years
91
10.9
745
89.1
0.463

    26 years and above
168
11.1
1344
88.9

Education

    None
46
10.2
407
89.8
0.268

    Qur’anic only
37
11.5
285
88.5

    Primary
69
12.9
467
87.1

    Secondary
80
9.6
755
90.4

    Higher
27
13.4
175
86.6

Geopolitical zones

    Northwest
71
15.5
366
84.5
0.016

    Northeast
47
10.4
405
89.6

    North-central
49
10.8
403
89.2

    Southwest
27
7.8
321
92.2

    Southeast
31
10.4
267
89.6

    South-south
34
10.0
307
90.0

Registered for ANC

    No
98
8.9
1002
91.1
0.001

    Yes
161
12.9
1087
87.1

Knowledge of dangers of malaria in pregnancy

    No
208
11.3
1638
88.7
0.269

    Yes
51
10.2
451
89.8

Knowledge that ITN prevents malaria

    No
134
7.6
1619
92.4
<0.001

    Yes
125
21.2
464
78.8

Ownership of a bed net

    No
5
0.3
1666
99.7
<0.001

    Yes
254
37.5
423
62.5

Knowledge of causes of malaria

    No
134
9.9
1220
90.1
0.024

    Yes
125
12.6
869
87.4

Risk of malaria in pregnancy

    Perceived it as not harmful
16
6.5
229
93.5
0.017

    Perceived it as harmful
242
11.6
1847
88.4

Misconception about causes of malaria

    No misconception
139
12.0
1017
88.0
0.074

    Had misconception
120
10.1
1072
89.9

Misconception about prevention of malaria

    No misconception
124
10.2
1093
89.8
0.100

    Had misconception
135
11.9
996
88.1

Knowledge of modes of prevention of malaria

    Not correct knowledge
147
8.5
1576
91.5
<0.001

    Correct knowledge
112
17.9
513
82.1

Total
259

2089

Table 3 presents findings from logistic regression model for use of ITNs. At an exploratory data analysis stage, several models were explored. However, we present the results for the model with best fit. Test of goodness-of-fit was based on Hosmer and Lemeshow test (HL). The test showed that the model presented here fits well to the data (). Exposure to mass media was observed to be positively associated with sleeping under ITN as those who listened to radio (OR = 1.56; 95% confidence interval 1.07 to 2.28; ) and had heard of the mass media campaign (OR = 1.53; 95% confidence interval 1.07 to 2.17; ) were about two times more likely to sleep under a bed net the night preceding the survey compared with their counterparts who did not. The knowledge that sleeping under ITN prevents malaria was significantly associated with sleeping under a bed net. Respondents with correct knowledge on use of ITNs were approximately three times more likely to sleep under ITNs compared with their counterparts who did not know that ITNs protect against malaria (OR = 3.15; ). Findings from this model also revealed a positive association between receiving IPT and use of ITN with those who received IPT about one and a half times more likely to sleep under ITNs (OR = 1.48; ). However, the significant effect of registering for ANC which was evident in the bivariate model disappeared after adjusting for other covariates. This implies that the net effect of ITN use by registration for ANC cancelled out after adjusting for other covariates.

Table 3: Results from logistic regression model 1 with respondents who slept under bed net as outcome variable.

Variable
Odds ratio
value
Confidence level

Lower
Upper

Northwest
1.53
0.07
0.96
2.45

Northeast
0.87
0.60
0.51
1.49

Southwest
0.98
0.95
0.57
1.69

Southeast
1.19
0.51
0.71
2.01

South-south
1.41
0.19
0.85
2.33

Secondary and higher education
0.74
0.06
0.53
1.02

Registered for ANC
1.19
0.31
0.85
1.65

Knew that using ITN prevents malaria
3.15
0.00
2.28
4.33

Listened to radio
1.56
0.02
1.07
2.28

Heard of campaign on ITN
1.53
0.02
1.07
2.17

Received IPT
1.48
0.02
1.06
2.08

5. Discussion

The role of mass media cannot be overemphasised in addressing reproductive health issues particularly in view of its potential for wide audience reach and cost-effectiveness in reaching large audiences. The use of ITNs during pregnancy has been shown in a systematic review to have a beneficial impact on pregnancy outcome in malaria-endemic Africa [22]. Although bed nets are available at most health facilities, some pregnant women still encounter difficulties accessing the nets [16].

Thus the promotion of net use is critical in the quest for the eradication of malaria in Africa. Combining the use of bed nets and IPT is perhaps the surest way of preventing malaria in pregnant mothers and this will in turn promote the health of mothers and their babies. Promoting use of ITNs, through mass media, has proved to be effective and has improved ITN use among pregnant women in Nigeria. ITNs when used by a large number of the target population within a community are effective not only in preventing malaria but also in generating a residual effect by significantly reducing vector populations thereby reducing rate of transmission [23], though this is presently still being discussed in the literature [24]. In addition the production of education and communication materials on malaria in pregnancy to be expanded and distributed nationally to all antenatal clinics in both private and government facilities, particularly in rural areas.

Although there have been increased efforts on the distribution of ITNs and education on their use in Nigeria, ITN ownership is still low as at the time of this survey. Reasons for poor use include misconceptions about ITNs and poor knowledge about the efficacy of ITNs in preventing malaria. There are still several misconceptions about malaria that negatively affects the number of pregnant women who use bed nets [25]. Efforts should be directed at uptake of antenatal services as soon as a woman confirms her pregnancy status. This will avail her opportunity of receiving ITNs (which are often distributed at no cost in most antenatal facilities) for the benefit of both mother and child. The low level of utilisation of ITNs has led to the call to expand the involvement of mass media [26] and the results of our study provide some evidence to support this call. This paper will guide policy makers and stakeholders in the planning and implementation of intervention in maternal and child health to adopt the mass media and an effective approach to reaching target groups and the general population.

6. Conclusion

The use of mass media in promoting the use of bed nets is effective. Respondents who knew that sleeping under ITN prevents malaria were 3.2 times more likely to sleep under net (OR: 3.15; 95% CI: 2.28 to 4.33; ). Those who listened to radio are about 1.6 times more likely to use ITN (OR: 1.56; 95% CI: 1.07 to 2.28; ), while respondents who had heard of a specific (monitored) sponsored radio campaign on ITN are 1.53 times more likely to use a bed net (). As much as one would have expected the respondents who have attained secondary education or higher to use net, findings showed a reverse relationship, although this was not statistically significant. The level of utilization of ITNs in Nigeria is still low. We advocate for expanded involvement of the mass media in community enlightenment programmes. Furthermore, efforts at the distribution of ITNs in all antenatal clinic outlets should be intensified.

7. Limitation of Study

In spite of the findings from this study, it is worth noting that a similar challenge of inability to establish causal relationship as in any cross-sectional study was encountered in this study. Further, the survey did not include questions to measure socioeconomic status of the respondents which are possible confounders to subject of interest. Therefore, we recommend that results be interpreted with an element of caution.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Authors’ Contribution

A. Ankomah, S. B. Adebayo, and J. Anyanti conceptualized the study and designed and wrote the study protocol and with M. Meremiku analyzed the data and wrote the initial draft. E. D. Arogundade, E. Nwokolo, U. Inyang, and Oladipupo B. Ipadeola managed the data collection from the various sites and wrote the literature review. All authors read and approved the final paper.

References

J. Ordi, M. R. Ismail, P. J. Ventura et al., “Massive chronic intervillositis of the placenta associated with malaria infection,” The American Journal of Surgical Pathology, vol. 22, no. 8, pp. 1006–1011, 1998.

C. Menendez, J. Ordi, M. R. Ismail et al., “The impact of placental malaria on gestational age and birth weight,” Journal of Infectious Diseases, vol. 181, no. 5, pp. 1740–1745, 2000.

O. A. Adefioye, O. A. Adeyeba, W. O. Hassan, and O. A. Oyeniran, “Prevalence of malaria parasite infection among pregnant women in Osogbo, Southwest, Nigeria,” The American-Eurasian Journal of Scientific Research, vol. 2, no. 1, pp. 43–45, 2007.

B. E. Bassey, J. E. Asor, and M. F. Useh, “Profile of malaria in pregnant women attending antenatal clinics in rural community in Nigeria,” The Open Parasitology Journal, vol. 1, pp. 1–6, 2007.

S. O. Coulibaly, S. Gies, and U. D'Alessandro, “Malaria burden among pregnant women living in the rural district of Boromo, Burkina Faso,” The American Journal of Tropical Medicine and Hygiene, vol. 77, no. 6, pp. 56–60, 2007.

A. M. Kabanywanyi, J. R. MacArthur, W. A. Stolk et al., “Malaria in pregnant women in an area with sustained high coverage of insecticide-treated bed nets,” Malaria Journal, vol. 7, article 133, 2008.

WHO, “A strategic framework for malaria prevention and control during pregnancy in the Africa Region,” Tech. Rep. AFR/MAL/04/01, World Health Organization, Geneva, Switzerland, 2004.

J. Picard, M. Aikins, P. L. Alonso, J. R. M. A. Schellenberg, B. M. Greenwood, and A. Mills, “A malaria control trial using insecticide-treated bed nets and targeted chemoprophylaxis in a rural area of The Gambia, West Africa 8. Cost-effectiveness of bed net impregnation alone or combined with chemoprophylaxis in preventing mortality and morbidity from malaria in Gambian children,” Transactions of the Royal Society of Tropical Medicine and Hygiene, vol. 87, supplement 2, pp. 53–57, 1993.

F. N. Binka, A. Kubaje, M. Adjuik et al., “Impact of permethrin impregnated bednets on child mortality in Kassena-Nankana district, Ghana: a randomized controlled trial,” Tropical Medicine and International Health, vol. 1, no. 2, pp. 147–154, 1996.

V. Wiseman, W. A. Hawley, F. O. Ter Kuile et al., “The cost-effectiveness of permethrin-treated bed nets in an area of intense malaria transmission in western Kenya,” The American Journal of Tropical Medicine and Hygiene, vol. 68, no. 4, pp. 161–167, 2003.

A. K. Mbonye, S. Neema, and P. Magnussen, “Treatment-seeking practices for malaria in pregnancy among rural women in Mukono District, Uganda,” Journal of Biosocial Science, vol. 38, no. 2, pp. 221–237, 2006.

L. J. Schultz, R. W. Steketee, L. Chitsulo, A. Macheso, Y. Nyasulu, and M. Ettling, “Malaria and childbearing women in Malawi: knowledge, attitudes and practices,” Tropical Medicine and Parasitology, vol. 45, no. 1, pp. 65–69, 1994.

G. Mubyazi, P. Bloch, M. Kamugisha, A. Kitua, and J. Ijumba, “Intermittent preventive treatment of malaria during pregnancy: a qualitative study of knowledge, attitudes and practices of district health managers, antenatal care staff and pregnant women in Korogwe District, North-Eastern Tanzania,” Malaria Journal, vol. 4, article 31, 2005.

M. Belay and W. Deressa, “Use of insecticide treated nets by pregnant women and associated factors in a pre-dominantly rural population in northern Ethiopia,” Tropical Medicine and International Health, vol. 13, no. 10, pp. 1303–1313, 2008.

B. A. Aina and F. A. Ayeni, “Knowledge and use of insecticide treated nets as a malaria preventive tool among pregnant women in a local government area of Lagos state, Nigeria,” Journal of Applied Pharmaceutical Science, vol. 1, no. 7, pp. 162–166, 2011.

O. I. Musa, G. A. Salaudeen, and R. O. Jimoh, “Awareness and use of insecticide treated nets among women attending ante-natal clinic in a Northern state of Nigeria,” Journal of the Pakistan Medical Association, vol. 59, no. 6, pp. 354–358, 2009.

J. O. Aluko and A. O. Oluwatosin, “Utilization of insecticide treated nets during pregnancy among postpartum women in Ibadan, Nigeria: A cross-sectional study,” BMC Pregnancy and Childbirth, vol. 12, article 21, 2012.

A. Agresti, An Introduction to Categorical Data Analysis, John Wiley and Sons, New Jersey, NJ, USA, 2007.

L. Fahrmeir and G. Tutz, Multivariate Statistical Modelling Based on Generalized Linear Models, Springer, New York, NY, USA, 3rd edition, 2001.

D. Collet, Modelling Binary Data, Chapman and Hall, London, UK, 2003.

D. Hosmer and S. Lemeshow, Applied Logistic Regression, John Wiley and Sons, New Jersey, NJ, USA, 3rd edition, 2013.

C. Gamble, P. J. Ekwaru, P. Garner, and F. O. Ter Kuil, “Insecticide-treated nets for the prevention of malaria in pregnancy: A systematic review of randomised controlled trials,” PLoS Medicine, vol. 4, no. 3, article e107, pp. 506–515, 2007.

M. N. Bayoh, D. K. Mathias, M. R. Odiere et al., “Anopheles gambiae: historical population decline associated with regional distribution of insecticide-treated bed nets in western Nyanza Province, Kenya,” Malaria Journal, vol. 9, no. 1, article 62, 2010.

W. Gu and R. J. Novak, “Predicting the impact of insecticide-treated bed nets on malaria transmission: the devil is in the detail,” Malaria Journal, vol. 8, no. 1, article 256, 2009.

A. Ankomah, S. B. Adebayo, E. D. Arogundade et al., “Determinants of insecticide-treated net ownership and utilization among pregnant women in Nigeria,” BMC Public Health, vol. 12, no. 1, article 105, 2012.

A. M. Abasiattai, E. A. Etukumana, and A. J. Umoiyoho, “Awareness and practice of malaria prevention strategies among pregnant women in Uyo, South Nigeria,” The Internet Journal of Gynecology and Obstetrics, vol. 11, no. 1, article 10, 2009.