Outcomes of a multifaceted intervention to prevent eclampsia and eclampsia-related deaths in Nigerian referral facilities

Abstract

Background

Eclampsia causes maternal mortality in Nigeria. This study presents the effectiveness of multifaceted interventions that addressed institutional barriers in reducing the incidence and case fatality rates associated with eclampsia.

Methods

The design was quasi-experimental and the activities implemented at intervention hospitals included a new strategic plan, retraining health providers on eclampsia management protocols, clinical reviews of delivery care and educating pregnant women and their partners. Prospective data were collected monthly on eclampsia and related indicators from study sites over 2 y. The results were analysed by univariate, bivariate and multivariable logistic regression.

Results

The results show a higher eclampsia rate (5.88% vs 2.45%) and a lower use of partograph and antenatal care (ANC; 17.99% vs 23.42%) in control compared with intervention hospitals, but similar case fatality rates of <1%. Overall, adjusted analysis shows a 63% decrease in the odds of eclampsia at intervention compared with control hospitals. Factors associated with eclampsia were ANC, referral for care from other facilities and older maternal age.

Conclusion

We conclude that multifaceted interventions that address challenges associated with managing pre-eclampsia and eclampsia in health facilities can reduce eclampsia occurrence in referral facilities in Nigeria and potential eclampsia death in resource-poor African countries.

eclampsia, interventions, maternal mortality, Nigeria, referral facilities

Introduction

Eclampsia, defined as severe hypertension in pregnancy with convulsive episodes in pregnant women, varies from 0.9% to 9.4% in Nigeria.^1,2 Studies suggest eclampsia is one of Nigeria's most common causes of maternal mortality.^3–5 In a national study of 998 maternal deaths and 1451 near-miss cases, eclampsia was the leading cause of maternal mortality, accounting for 28% of maternal deaths.⁶ Several formative research projects have described the prevalence, epidemiology, risk factors and outcomes of eclampsia in different parts of the country;^2,7–9 limited interventional research has been conducted to improve the management of eclampsia and prevent its occurrence in Nigeria. Most interventions related to pre-eclampsia/eclampsia were designed to address singular aspects of the eclampsia causative continuum. These include building the capacity of health workers to manage pre-eclampsia and eclampsia,¹⁰ increasing the quality and use of antenatal care (ANC),¹¹ the widespread use and availability of magnesium sulphate and antihypertensive drugs,¹² improving the quality of emergency obstetric services¹³ and increasing transportation/referral services.¹⁴ However, a single intervention for preventing eclampsia can only be effective in countries with developed health systems where an intervention targets a single deficit. In contrast, in a low-income country with a weak healthcare system such as Nigeria, effective prevention of eclampsia relies on addressing the multiple layers of deficits in the pathways that increase the prevalence, severity and death from eclampsia.

Published studies suggest the background factors that increase the risk and death rates from eclampsia include misinterpretation by women and caregivers of the natural causes of eclampsia,^15,16 the tendency not to attend ANC and giving birth outside the healthcare system,¹⁷ as well as delays in seeking treatment for eclampsia¹⁸ and delays in receiving care in health facilities.¹⁹ Consequently, potential risk factors for eclampsia that should be addressed include improved quality of ANC to ensure the early detection of pre-eclampsia, counselling of women and their caregivers to improve the use of recommended measures for the prevention and management of pre-eclampsia/eclampsia, sustained availability and training of clinic staff on the prevention and management of eclampsia, improved quality and responsiveness of emergency obstetrics care and capacity building of clinic staff to use validated algorithms and protocols for the management of pre-eclampsia and eclampsia.

We speculated that multifaceted interventions that simultaneously address multiple bottlenecks would be more effective in preventing eclampsia than single-action interventions because multiple processes and structural factors predispose women to pre-eclampsia/eclampsia. The Community Level Interventions for Preeclampsia (CLIP) study, conducted in Nigeria and several other African countries,²⁰ used multiple interventions at the community level to improve the prevention and health-seeking behaviour for pre-eclampsia and eclampsia, with varying degrees of success. To our knowledge, no such participatory action research has ever been conducted for preventing eclampsia in health facilities, an approach that we speculate would be more effective than single-action or community-based interventions.

This study assessed multistage interventions co-designed and implemented with relevant stakeholders that addressed multiple background factors predisposing women to eclampsia and related deaths in Nigeria's referral hospitals. In the first stage of the study we conducted formative research to understand better the context of eclampsia occurrence in eight Nigerian referral hospitals in four of the six geopolitical zones in the country.^21,22 In the second stage we used the results of the formative research to co-design and implement multifaceted interventions in partnership with heads of hospitals, healthcare providers and policymakers to address the multiple bottlenecks identified in the formative research. Intervention activities were implemented in two hospitals in the second phase. In the third and final phase we monitored the effects of the intervention on incidence and death rates from eclampsia in the intervention and control hospitals. This study aimed to assess the effectiveness of multifaceted interventions in reducing the incidence and case fatality rates of eclampsia.

Primary post-partum haemorrhage (PPH), eclampsia and obstructed labour are the leading causes of maternal mortality in Nigeria. While PPH and eclampsia are potential adverse maternal outcomes, they have very different clinical indications requiring separate and specific management. We used the same intervention approaches to address PPH, eclampsia and other potential adverse maternal outcomes. The PPH study has been published elsewhere²³ and the current article is focused on the outcomes of the study on pre-eclampsia.

Methodology

Study design and setting

The study was part of a comprehensive program aimed at improving the quality of care for managing the three major complications of pregnancy (PPH, eclampsia and obstructed labour) that lead to the high rate of maternal mortality in Nigeria.²⁴ The study used a quasi-experimental design that included specific interventions for the prevention of eclampsia in two referral hospitals (one in the south and the other in northern Nigeria). In comparison, two referral hospitals in comparable locations in the southern and northern parts of the country served as the control hospitals. The intervention hospitals were the Central Hospital in Benin City and the General Hospital in Minna. The control hospitals were the Central/General Hospitals in Warri, Suleja and Abuja and serve as referral hospitals for women who intend to deliver at home, church, rural clinics or other small hospitals. These hospitals serve large populations of women in four states and two geopolitical zones of Nigeria and offer primary and comprehensive obstetric care. The paired intervention and control hospitals are 80–120 km apart to ensure sociocultural comparability of the data between the intervention and control hospitals.

The baseline research consisted of mixed method qualitative and quantitative research that informed the design of the intervention in the hospitals. The methods and results of the formative research have been described elsewhere.²⁵

Intervention design and implementation

The interventions consisted of strategic visioning and a plan to improve antepartum, intrapartum and delivery care; retraining of maternal health providers to improve antenatal, delivery and post-natal care for the early recognition of pre-eclampsia; provision of protocols, algorithms and reminders and their use by providers on optimal antenatal, intrapartum and post-natal care for pre-eclampsia and eclampsia; clinical reviews of delivery care; and health education provided to pregnant women and their partners on early treatment seeking and the prevention of pre-eclampsia/eclampsia. The details of the intervention activities are provided below.

Strategic planning for improved delivery care

We ascertained the strengths, weaknesses, opportunities and threats (SWOT analysis) for providing optimal maternal healthcare for the prevention of pre-eclampsia and eclampsia in conjunction with hospital staff. We then identified the challenges that needed to be addressed and developed a strategic plan for implementing the intervention activities. The medical directors of the hospitals worked with a committee consisting of the heads of the obstetrics and gynaecology departments, the head matrons and consultant obstetricians and gynaecologists to implement the activities identified in the plan. We agreed on the shared vision to reduce the rate of maternal mortality in the hospitals by 50% over 2 y by reducing the incidence and improving the management of PPH, eclampsia and obstructed labour.

Retraining of maternal healthcare workers

Retraining the nursing, midwifery and medical staff working in the maternity sections of the hospitals was focused on the deficits in early recognition and prevention of pre-eclampsia and eclampsia through improved quality of ANC and management of delivery and post-natal periods. We conducted a 5-d training for hospital staff in the intervention hospitals, focusing on the mechanism of ANC and pathophysiology. The clinical presentation, prevention and management of hypertensive diseases of pregnancy (including pre-eclampsia and eclampsia) and the new methods (including the use of magnesium sulphate) recommended by the World Health Organization (WHO) for the prevention and management of pre-eclampsia and eclampsia were taught. The training was facilitated by experienced obstetricians and midwives and consisted of lectures, clinical demonstrations, role playing and discussions. Responses to post-lecture compared with pre-lecture questions showed increased knowledge scores that participants attained at the workshop's end.

Development of management protocols, algorithms and reminders

As part of the staff retraining, protocols and algorithms for managing ANC, hypertensive diseases in pregnancy and eclampsia were co-developed with the participants and printed for use in different sections of the hospital's maternity unit. Specifically, we developed a protocol for measuring and interpreting blood pressure and pre-eclampsia, categorizing pre-eclampsia into mild or severe and managing pre-eclampsia/eclampsia with aspirin, magnesium sulphate and antihypertensives (specifically labetalol) and with ancillary measures at various stages in pregnancy. We also ensured that all hospital blood pressure–measuring instruments were functioning and well calibrated. All drugs (aspirin, magnesium sulphate, antihypertensives and sedatives) for managing pre-eclampsia and eclampsia are available in hospitals.

Clinical reviews of delivery care and maternal mortality

Daily reviews of the management of labour were commenced in the hospitals. Although the hospitals previously held daily meetings, we restructured the meetings to include reviews of all cases of pregnant women with hypertension and hypertensive emergencies occurring in the units during the period and to identify situations where the management protocols were breached. We emphasized sharing knowledge of eclampsia prevention and early detection procedures, as well as the appropriate management of hypertensive diseases during pregnancy. During these periods, all maternal deaths were reviewed in the departments before they were submitted for further review by the hospitals’ maternal mortality reviews and surveillance committees. The results²⁶ were used to improve hypertensive disease management in the hospitals.

Health education and feedback from women

Weekly meetings were organized with pregnant women registered in the hospitals and their spouses during the intervention period. The women were enrolled in the educational sessions when they registered for ANC and were encouraged to return to subsequent sessions. The meetings were organized on Saturdays to allow staff to interact with the women and their caregivers. Sixty-six sessions were held during the period. Some weeks were skipped because of holidays and other special duties, but the weekly meetings have become the norm in the intervention hospitals since then. The sessions consisted of presentations made by senior clinical care providers on various aspects of maternity care, followed by question-and-answer sessions. The women watched videos of normal labour admission procedures and steps in ANC and labour. We also shared information about the risks associated with pre-eclampsia/eclampsia, how they can be prevented and recognized and the clinical procedures that have been put in place in hospitals to manage them. The sessions included the distribution of an information leaflet on questions frequently asked by pregnant women (written in the English and Hausa languages) developed as part of the intervention.

Data collection

We collected monthly data prospectively from October 2017 to June 2019 in participating hospitals, including the number of deliveries, number of deliveries complicated by pre-eclampsia and eclampsia, cases of pre-eclampsia/eclampsia adequately managed according to standard WHO protocols and the number of eclampsia-related maternal deaths. These data were collected with a standard protocol by trained hospital data collectors over 21 months, and the first 3 months represented the baseline period. Intervention and follow-up activities occurred in the 18 months that followed. The data were collected with computer-assisted personal interviewing software installed on smartphones, which were returned to the central processing unit at the Women's Health and Action Research Centre for collation and data analysis. We used a structured questionnaire to obtain information on the sociodemographic characteristics of all women who delivered in the participating hospitals. Process and outcomes data included cases of pre-eclampsia/eclampsia correctly treated with magnesium sulphate and antihypertensives drugs. Data on ANC within or outside the health facility, birth outside the health facility, the mode of delivery (whether vaginally or by caesarean section) and referral to the hospitals from other health facilities were also collected. Other data collected included eclampsia cases, maternal deaths due to eclampsia and maternal death due to other causes.

Data analysis

The analysis aimed to determine the effect of intervention activities on eclampsia occurrence and it was assumed that the eclampsia rate and eclampsia-related deaths would be lower in the intervention compared with the control hospitals. The dependent variable was eclampsia and the independent variables were the sites (control and intervention) and the study period (baseline and intervention periods). Eclampsia occurrence was abstracted from monthly patient records for 21 months of the study duration. The first 3 months were the baseline period. Implementation of intervention activities started in the fourth month. It continued until month 11, which suggests the intervention effect may not be significant in the early period of the intervention but towards the later months of the observation period.²⁶ We segmented the study duration into baseline (months 1–3), intervention (months 4–11) and post-intervention (months 12–21) to determine whether the effect of the intervention varies with time. The baseline period served as the reference. Descriptive analyses consisted of a t-test and Wilcoxon rank-sum test to determine the difference in means of age (parametric), parity and gravidity (non-parametric) between the intervention and control hospitals. Chi-squared was used to assess the difference in the occurrence of eclampsia at the control and intervention hospitals. We aggregated monthly rates of eclampsia per 1000 (as the monthly counts of eclampsia divided by the monthly total of women who delivered at each hospital).

Similarly, we obtained the rate of magnesium sulphate and partographs monthly and described differences in the average monthly rate at the intervention and control hospitals. This study also compared case fatality rates from eclampsia (the number of deaths divided by the total number of cases multiplied by 100) between the intervention and control hospitals. There were only six deaths due to eclampsia during the study period. The small number of eclampsia deaths precluded further analysis of differences in death rates and risk factors.

We also analysed hospital-level data, with the rate of eclampsia as the dependent variable. Using the repeated measures mixed model restricted estimation maximum likelihood approach, we evaluated the intervention effect on eclampsia rate within and between the control and intervention hospitals. In addition, we used multiple logistic regression models to explore the interaction between study duration segments and intervention/no intervention to see whether the odds of eclampsia vary at the intervention and control hospitals over time. Statistical significance was defined as p<.05. Analyses were conducted using SAS 9.4 and JMP 16 (both from SAS Institute, Cary, NC, USA).

Results

Description

Data were prospectively extracted for 18 181 women during the study period. Of these, 54% were from the intervention hospitals (Benin and Minna), while 46% were from the control hospitals (Warri, Abuja and Suleja). Control and intervention hospitals were significantly different in most characteristics. Women in the control hospitals were slightly older, employed, had higher gravidity, had a higher proportion who did not receive ANC and lived in rural areas. The eclampsia rate per 1000 discharges was higher in the control than in the intervention hospitals (59.29±20.92 vs 25.66±17.43). The mean count of eclampsia patients who were administered magnesium sulphate was higher in the control than in the intervention hospitals, but the difference was not statistically significant. Conversely, the average number of recorded partographs was lower in the control hospitals than the intervention hospitals (174.65±53.13 vs 252.48±64.34). Six eclampsia deaths occurred in all hospitals during the study period. The case fatality rate was approximately 1% at both intervention and control hospitals, which was not statistically significant (Table 1).

Table 1.

Descriptive characteristics of women who received care at intervention and control hospitals

Characteristics	Control hospital (N=8378)	Intervention hospital (N=9740)	p-Value
Age of mother (years), mean (SD)	30.29 (5.29)	29.07 (5.62)	<0.0001
Parity, mean (SD)	1.85 (1.62)	2.27 (1.77)	<0.0001
Gravidity, mean (SD)	3.56 (2.03)	3.29 (2.03)	<0.0001
Eclampsia rate/1000 discharges, mean (SD)	59.29 (20.92)	25.66 (17.43)	<0.0001
Partographs (n), mean (SD)	174.65 (53.13)	252.48 (64.34)	<0.0001
Magnesium sulphate administered, n (%)	9.08 (4.69)	7.69 (5.54)	0.2309
Eclampsia, n (%)			<.0001
Yes	493 (5.88)	240 (2.45)
No	7888 (94.12)	9562 (97.55)
Eclampsia deathsa, n (%)			0.9753
Yes	4 (0.81)	2 (0.83)
No	489 (99.19)	238 (99.17)
ANC, n (%)			<0.0001
No	1507 (17.99)	2296 (23.42)
Yes	6871 (82.01)	7506 (76.58)
Education level, n (%)			<0.0001
No education	39 (0.47)	2782 (28.38)
Arabic education	189 (2.26)	59 (0.6)
Primary	814 (9.72)	572 (5.84)
Secondary	4883 (58.28)	3933 (40.12)
Tertiary	2453 (29.28)	2456 (25.06)
Referred to the hospital, n (%)			0.001
Yes	287 (3.43)	429 (4.38)
No	8091 (96.57)	9373 (95.62)
Residence, n (%)			<0.0001
Urban	7271 (86.79)	8873 (90.52)
Rural	1107 (13.21)	929 (9.48)
Marital status, n (%)			<0.0001
Never married	235 (2.8)	78 (0.8)
Married	8140 (97.16)	9721 (99.17)
Widow	3 (0.04)	3 (0.03)
Number of babies, n (%)			0.0049
Singleton	8149 (97.27)	9457 (96.48)
Twin	222 (2.65)	339 (3.46)
Triplet	6 (0.07)	5 (0.05)
Occupation, n (%)			<0.0001
Unemployed	2311 (27.58)	4651 (47.45)
Employed	6067 (72.42)	5151 (52.55)

^aCount represents eclampsia case fatalities among 733 eclampsia cases during the study period.

Adjusted analyses

The difference in the average eclampsia rate in the intervention hospitals relative to the control hospitals was significant in the mixed model (p=0.0069). The overall month-to-month eclampsia rate differences and changes in monthly rates between the control and intervention hospitals were not significant. In the adjusted logistic regression analysis, the interaction term for time and intervention/control site was significant. The results show the intervention was associated with a 63% decrease in eclampsia (odds ratio [OR] 0.37 [95% confidence interval {CI} 0.3 to 0.46]). Factors associated with eclampsia included ANC (OR 0.68 [95% CI 0.57 to 0.82]), referred for care as compared with not referred from other facilities (OR 4.86 [95% CI 3.82 to 6.17]) and increasing age (Table 2). Figure 1 shows the probability of eclampsia occurrence at the intervention and control sites from baseline to the end of the study. The probability of eclampsia was lower at the intervention hospitals and higher at the control hospitals (See also Appendix 1 for the frequency of eclampsia by referral status). Similarly, Figure 2 shows the probability of eclampsia in different study periods varied at the control and intervention hospitals. The odds of eclampsia decreased with time in the intervention sites compared with the control sites. In months 12–21 there was 41% decreased odds of eclampsia at the intervention sites.

Figure 1.

Predicted probability of eclampsia occurrence.

Figure 2.

Probability of eclampsia in different study periods.

Table 2.

The adjusted odds of eclampsia occurrence at intervention and control hospitals between October 2017 and June 2019

Category	OR	95% CI	p-Value
Intervention (ref=control)	0.37	0.31 to 0.46	<0.0001
Segments of study duration (months) (ref: months 1–3)
4–11	1.14	0.91 to 1.42	0.2581
12–21	0.90	0.70 to 1.16	0.4247
Months 4–11 vs baseline in control hospitals	1.23	0.92 to 1.65	0.1555
Months 12–21 vs baseline in control hospitals	1.38	1.03 to 1.84	0.0287
Months 4–11 vs baseline in intervention hospitals	1.05	0.75 to1.47	0.7890
Months 12–21 vs baseline in intervention hospitals	0.59	0.39 to 0.89	0.0121
Age	1.03	1.01 to 1.05	0.0006
Parity	0.95	0.90 to 0.99	0.0296
Unemployed (ref: employed)	1.17	0.98 to 1.40	0.0779
Received ANC (ref: no)	0.68	0.57 to 0.82	<0.0001
Not referred to hospital (ref: yes)	4.86	3.82 to 6.17	<0.0001
Multiple babies delivered (ref: single)	1.87	1.33 to 2.61	0.0003

Bold values are significant.

ref: reference.

Discussion

The study investigated the effectiveness of a multifaceted intervention to reduce the incidence of eclampsia and case fatality rates from eclampsia. The results show a 63% decrease in eclampsia rates in intervention hospitals compared with control hospitals. In the adjusted analysis, the factors associated with the reduced odds for eclampsia at the intervention sites were ANC, a referral from other facilities and older maternal age. Interestingly, the prevalence of magnesium sulphate use in patients with severe pre-eclampsia to prevent eclampsia did not differ between the intervention and control sites.

In a systematic literature review based on a decision tree mathematical analytical model, Goldenberg et al.²⁷ evaluated interventions designed to reduce eclampsia-related maternal mortality in low-income African countries. The results showed that increased use of pre=eclampsia/eclampsia diagnostics, transfer to higher levels of care and increased hospitalization with caesarean section/induction of labour reduced maternal mortality rates from eclampsia. In contrast, increased use of magnesium sulphate demonstrated a much smaller effect in reducing maternal mortality from pre-eclampsia/eclampsia.

In this study, although more women received ANC in the intervention than control sites, the number of women in both sites in the primary labour phase was similar. Only a few women (<5.0%) were referred from other health facilities while in labour. Thus it is likely that the improved quality of ANC, especially the instructions provided to women during ANC sessions on the need for early recognition and treatment of pre-eclampsia may account for the reduced prevalence of eclampsia in the intervention as compared with the control sites. Although magnesium sulphate use was similar in both sites, results suggest the intervention sites managed labour more intensively than the control sites, as illustrated by their higher use of partographs. This may explain the reduced prevalence of eclampsia and fewer records of magnesium sulphate use in the intervention sites.

Several primary prevention measures for pre-eclampsia that resulted in eclampsia identified in the literature include calcium supplementation; antiplatelet agents; early diagnosis of pre-eclampsia with serum uric acid, creatinine and urinary microprotein levels;^28,29 and dietary supplementation with vitamins C and E.³⁰ None of these prevention methods were reported in this study, making this population completely naïve to primary eclampsia prevention methods. Including these primary prevention methods may further reduce the incidence of pre-eclampsia and eclampsia in women attending health facilities.

This study also compared case fatality rates from eclampsia (between the intervention and control hospitals. The results show relatively low case fatality rates that were not significantly different in both groups. This may indicate either low reporting of deaths or an actual low incidence of death. It may also indicate a non-comparable severity of eclampsia between the control and intervention sites, making it difficult to compare the death rates between the two groups. However, we did not investigate this possibility further.

Available reports in the literature³¹ indicate that eclampsia is a disease often associated with near-miss cases, where aggressive and purposeful medical interventions may avert death. Therefore, the aggressive application of prevention and treatment methods for eclampsia may have reduced the incidence of eclampsia and related deaths at the intervention hospitals. To compare death rates between the intervention and control hospitals, we should compare various indicators such as the quality of service, quantity and quality of available resources, personnel experience and team approach to eclampsia management. Our inability to include such details is a weakness of the study, providing lines of action for future studies.

Strengths and limitations

This study has several strengths and weaknesses. The major strength is the baseline formative research, which identified factors that impede the effective delivery of services to prevent pre-eclampsia and eclampsia. Focusing on the subsequent interventions to address these barriers was an important innovation and strength of the study. Using large referral hospitals in two regions of the country with high caseloads of eclampsia possibly increased the external validity and generalizability of the study results. To the best of our knowledge, this study is one of a few studies in Nigeria that has prospectively collected data on eclampsia, enabling estimation of incidence rates and trends of eclampsia occurrence in the country. We believe this study can inform on ways to conduct prospective multicentre studies and future intervention and implementation research for preventing eclampsia and reducing eclampsia-related deaths.

The study's major limitation is that despite the large size of the country, only four referral hospitals (two intervention and two control hospitals) participated in the study. This was due to our desire to ensure the effective implementation of the study, given the limited budget available. Involving senior management officials of the hospitals in the research and in-kind and cash contributions by the hospitals ensured the cost-effective implementation of the project activities. Also, patients were not randomized to intervention and control sites, as it was not feasible, so the study findings do not infer a causal relationship. There were missing data on essential indicators due to the lack of a collection of broad clinical indicators at the hospitals. However, with repeated data review and cleaning, we obtained the most accurate data that informed the report presented in this article. Future collaborative and multicentre data collection design in a low-resource setting should lengthen field staff training and include robust pilot testing to mitigate potential implementation challenges.

We conclude that multifaceted interventions that address challenges associated with managing pre-eclampsia and eclampsia in health facilities can reduce the prevalence rate of eclampsia in referral facilities in Nigeria. The reduced prevalence of eclampsia is attributable to improved ANC practices for pre-eclampsia. These practices can reduce the severity and death rates from eclampsia in Nigeria and other resource-poor African countries.

Authors’ contributions

OFE was responsible for the conceptualization of the study. OFE, RO, WI, GH and LN were responsible for the design and execution of the intervention activities. OFE, RO, LN and GH were responsible for the formative research. OFE, BE and EC were responsible for manuscript development and preparation. BE was responsible for data analysis. OFE, VO, KA, BI and LN were responsible for supervision of the study and data collection. All authors were responsible for review of final version of the manuscript.

Acknowledgements

None.

Funding

The project was funded by the Alliance for Health Policy and Systems Research of the World Health Organization, through its program on improving implementation research on maternal health in developing countries (protocol A65869). The funding body did not have any role in the design of the study; collection, analysis, and interpretation of data; or manuscript writing.

Competing interests

None declared.

Ethical approval

Ethical approval for the study was obtained from the WHO and the National Health Research Ethics Committee (NHREC) of Nigeria (NHREC/01/01/2007–16/07/2014, renewed in 2015 with NHREC 01/01/20047–12/12/2015b). The chief medical directors, heads of departments of the hospitals and the participants were informed of the purpose of the study and verbal consent was obtained from them to conduct the study. They were assured of the confidentiality of the information obtained. No names or specific contact information were obtained from the study participants. The study was registered in the Nigeria Clinical Trials Registry on 14 April 2016 ( no. 91540209; http://www.nctr.nhrec.net/) and with the ISRCTN on 14 August 2020 (no. 64 ISRCTN17985403; https://doi.org/10.1186/ISRCTN17985403).

Data availability

Data can be obtained from the corresponding author upon request.

Appendix 1.

Eclampsia status among referred and non-referred women at the intervention and control hospitals

	Intervention		Control
Eclampsia	Referred, n (%)	Non-referred, n (%)	Referred, n (%)	Non-referred, n (%)
Yes	50 (11.7)	190 (2.03)	61 (21.25)	432 (5.34)
No	379 (88.3)	9163 (97.9)	226 (78.7)	7660 (94.7)