Table 1 gives information on study design of the papers included. Fourteen of the papers included were impact studies, including 11 cohort studies, two cross-sectional studies and one review of records. The other fifteen papers were either qualitative or mixed method in research design. In two cases, no research design was reported. The dates of the studies ranged from 1978 to 2013, with the majority published between 2003 and 2013. Below we organize the analysis of implementation factors extracted from the different studies into five main categories.
Maternity waiting homes settings and target populations
The included studies on MWHs were from countries in Africa (nine countries – Eritrea, Ethiopia, Ghana, Kenya, Liberia, Malawi, South Africa, Zambia, Zimbabwe), Latin America (four countries – Cuba, Guatemala, Honduras, Nicaragua, Peru], and Asia (three countries - Lao PDR, Nepal and Timor-Leste).
Reported interventions were generally confined to a few districts involving one to five MWHs. However, articles from Cuba and Peru reported larger numbers of MWHs being built [16, 23]. The majority of settings were rural. Some specifically targeted conflict areas, indigenous women, the socially excluded, or poor people. [17, 24, 25] Depending on the location of the MWH, women travelled from less than 5 km to 400 km to reach the closest MWH [10, 15]. Along with large distances, several studies reported women having to cross difficult terrain to reach the facility. Most MWHs were situated next to a hospital facility, which provided essential childbirth care services and care for complications (comprehensive obstetric care services), although a few were placed near health centres that provided only essential childbirth care. Practices of referral to MWHs varied; women were referred by health professionals, from antenatal clinics or self-referred.
Administrative set up and maintenance of maternity waiting homes
There is diversity in the stakeholders who took responsibility to establish the MWHs in the different studies included. The programmes in Cuba and Peru were large scale and, at least initially, adequately funded and supported by their respective National Ministries of Health. These MWHs were implemented as part of a national programme to improve maternal health outcomes, alongside new protocols, staff training, and improved referral and support for women [16, 23]. Aside from these examples, little information was found on policy support for MWHs at a national level.
The remainder of the MWHs consisted of isolated projects, supported by non-governmental and donor organisations. A number of articles reported community support and contribution to the setup and ongoing running of the MWH. The need for the community to be involved in the set up and maintenance of the MWH was identified in three studies, and six studies identified the absence of community involvement as a reason for low utilization of the MWH programme [13, 17, 26,27,28,29].
Several studies reported on MWH residents incurring user fees for antenatal care or childbirth services [10, 17, 25, 29,30,31,32,33]. The removal or reduction of costs associated with using the MWH and subsequent institutional birth were noted as important strategies for increasing MHW use. In two studies, financial incentives were even offered for women, who were charged less for childbirth services if they stayed in the MWH [13, 17]. The provision of free food by the MWH varied across settings. In Cuba, meals were provided and tailored to the nutritional needs of each woman in consultation with dieticians at the MWH , while in other MWHs, food or kitchen facilities were available for the women to arrange their own meals [10, 16, 18, 31, 33]. However, in instances where women and their families were required to provide their own meals, inequalities in terms of volume and quality of food emerged among the women [10, 13, 33, 34].
A number of studies reported that simply building a MWH did not overcome barriers to accessing care as women still needed financial resources to get to the MWH [15, 17, 25, 28, 30]. The cost of public transportation to reach the MWH was a common barrier to its use and varied depending on the mode of transport distance and time of day . Considerable costs were also reported for securing private transport. The comfort and speed of the transport, as well as the terrain covered were other elements considered by women [13, 30]. In Laos PDR, women were refunded transport costs. In Nicaragua and Laos PDR, women and their families indicated that upfront support for transportation costs would be important [23, 30].
Physical infrastructure and facilities provided
A range of building types were used for MWHs, including unused wards of hospitals , traditional huts  and purpose-built structures. Some buildings had several separate rooms, each with a few beds , while others had large dormitories . Total bed space ranged from 4 to to 83 . In planning for the construction of a MWH in South Africa, Larsen et al. estimated that the size of a MWH should be based on 500 women per 1000 births in a district, with each stay averaging two weeks .
Living and social spaces, as well as utilities like electricity or water, kitchens, cooking utensils, toilets and bathrooms, lockers, bedding and firewood, were described in some papers. From the perspectives of women who used the facility, a lack of privacy, poor toilet and bathing facilities, poor or inadequate kitchen facilities, the non provision of food, and lack of space for women to stay post-partum were considerable barriers to MHW use. [10, 13, 15, 17, 25, 27,28,29,30, 36, 37] Overall, MWHs were better used and accepted by women and their families when they provided basic infrastructure and facilities such as those mentioned above [17, 27, 36, 37]. In one MWH in Ethiopia the availability of a hot shower was very popular with women .
In some situations, accommodation was provided for relatives, including mother in laws [17, 28]. Women cited companions not being allowed – either at the MWH or in the facility – as an additional factor undermining acceptability of MWHs [10, 15, 17, 25, 30]. Finally, in interviews with women and families, acceptability of MWH was noted as being higher if activities were available for women to do while awaiting childbirth, such as health education and income generation activities [14, 16, 17, 33].
Health services and linkages with the facility
Various criteria were used to accept women into MWHs, from identified obstetric risk factors for complications, to open admission. Women were advised to stay for between one to four weeks before childbirth and, in some MWHs, for up to seven days after birth. Two studies suggested that sometimes uncertainty around a woman’s due date meant that she did not know when it was appropriate to come to the MWH [30, 32]. MWHs were sometimes also used as places for women to stay before and after undergoing postpartum tubal ligation at the hospital or other health facilities [10, 33, 38].
Studies suggest that strong referral and communication systems between the MWH and the facilities they are linked to are important, as well as a focus on providing high quality care in both the MWH and the facility linked to the MWH [14, 16, 17, 25, 26, 32, 34, 37, 39, 40]. The type and quality of maternity care services received by women varied. Three studies noted that there were no regular visits by health care providers to the MWH and that referral from the MWH to the facility was not smooth [10, 29, 36]. In other sites, women regularly attended the nearby health facility, or were visited in the MWH by staff from the facility [14, 26, 31]. Standard guidelines for care processes, including criteria for admissions, diagnostic and clinical guidelines for identifying risk factors, and protocols for treatment in MWH settings, were reported in Cuba .
Community involvement and sensitivity to cultural norms
Linking with traditional birth attendants (TBAs) was seen as enabling the success of MWH programmes. Five studies identified this as critical to facilitating access to MWHs, specifically, through the training of TBAs and the integration of them into the preparation for birth and birthing process both at the MWH and at the facility [24,25,26,27, 39].
In four studies, the integration of cultural norms around birthing and improved awareness that the MWH provided respectful and humanized care were key to getting women and their families to use both MWH and the nearby facility for birth [17, 23,24,25]. Finally, on the issue of cultural norms, concerns were expressed by women in Guatemala around health workers belonging to a different cultural group to those attending MWH, and the potential for this to pose linguistic challenges and also to undermine respect for a woman’s cultural beliefs [17, 31].
A number of studies identified outreach to the community, often using existing community health structures, as key to the success of a MWH project [25,26,27,28].
Community involvement was important to identify cultural factors that affected the use of the MHW; for example, family members, namely the husband or mother-in-law, would not “allow” women to use the MWH or to be away from the household for an extended length of time due to childcare and other household duties [17, 27, 31, 36, 37]. Awareness building efforts were especially important in places where community members had little knowledge of the MWH, which in itself constituted an important barrier to MWH use [17, 28, 36].
Overall, activities to increase community awareness of the MWH services were considered a vital facilitator of MWH uptake [10, 13, 15, 25, 26, 31]. MWHs were embraced in those communities where family members and the larger community had been made aware of the importance of facility births [10, 13, 15, 17, 24, 25, 28, 31].