The new series calls for immediate action to reduce global rates of maternal mortality.
Over a total of six papers, the new series looks at quality of health care for women and babies worldwide, with a particular focus on the differences in care between high- and low- to middle-income countries.
Additionally, the series points to a number of strategies to improve maternal health care services across the globe, in order to meet Sustainable Development Goals (SDGs) adopted by the United Nations (UN) in September last year.
As part of these SDGs, the UN aim to reduce the global mortality rate to less than 70 per 100,000 live births by 2030, as well as ensure there is universal access to sexual and reproductive health care services.
In the first paper of the series, Prof. Wendy Graham, of the London School of Hygiene & Tropical Medicine in the United Kingdom, and co-authors look at the burden of poor maternal health worldwide.
They note that over the past 25 years, progress has been made in reducing maternal mortality rates worldwide, but much more needs to be done, since major disparities remain.
"In all countries, the burden of maternal mortality falls disproportionately on the most vulnerable groups of women," says Prof. Graham. "This reality presents a challenge to the rapid catch-up required to achieve the underlying aim of the SDGs - 'to leave no one behind.'"
Poor access to quality maternal health care services remains a problem
According to the series authors, the burden of maternal mortality is primarily down to poor access to quality maternal health care services, which vary widely worldwide.
In the third paper, co-author Prof. Oona Campbell - also of the London School of Hygiene & Tropical Medicine - and colleagues state that around 25 percent of newborns across the globe are delivered without the aid of a skilled birth attendant.
The authors note that 90 percent of maternal deaths occur in 58 countries that have only 17 percent of the world's midwives and doctors, highlighting the importance of skilled medical professionals.
What is more, in regions where women do have access to birth facilities, there are large discrepancies in care quality.
As an example, the authors point to a study that found 56 percent of birth facilities in Tanzania were conducting deliveries without basic needs, such as water and electricity.
Additionally, individual patient care can be poor in low- and middle-income countries. This is largely due to poor staff training and lack of quality guidelines, according to the authors of the second paper, who conducted a systematic review of clinical-based practice guidelines for maternal care.
"We identified no high-quality maternal health guidelines from LICs [low-income countries], which was of great concern, although our review did not consider activities or efforts in adaption and implementation of international guidelines to local settings," say the authors.
Prof. Campbell comments that it is "unethical" to encourage women to give birth in poor quality facilities with no skilled attendants. "This failing should be remedied as a matter of priority," she adds.
Wide disparities in maternal mortality across high-income countries
While maternal mortality rates are falling in high-income countries, the authors of the fourth paper say large disparities remain at national and international levels.
In the United States, for example, maternal mortality is at 14 per 100,000 live births, compared with 4 per 100,000 live births in Sweden.
Most births in high-income countries occur in hospitals, the authors report, with most accompanied by a skilled birth attendant.
However, the authors stress that not all care provided in these countries is based on clinical evidence, and there needs to be more focus on care surveillance in order to better understand the causes of maternal deaths that do occur.
Furthermore, the series authors say there are a number of barriers to high-quality maternal care that need to be addressed in high-income countries, such as increasing obesity rates and the rising age of pregnancy.
Key strategies to reduce maternal mortality
The final paper of the series lays out a number of key priorities that need to be addressed immediately in order to meet the SDG maternal mortality target.
Firstly, the authors say high-quality maternal health care services that address patients' individual needs should be put in place across the globe.
"Each country needs a clear national statement of what care needs to be provided to pregnant women, what constitutes routine care for uncomplicated deliveries, and what mechanisms are required to respond on a timely basis to complicated deliveries, including referral linkages," they explain.
"Countries then need to carefully compare this national statement with their present situation using tools such as facility and population-based surveys, or routine information systems."
There should also be universal access to high-quality maternal health services, as a way of ensuring all women and babies receive equal care, regardless of where they are in the world.
The authors add:
"Every universal health coverage initiative should include a strong maternal health service core and ensure that it reaches every woman, everywhere with quality care, and without causing financial hardship and pushing families into poverty."
Health systems worldwide also need to be strengthened, which incorporates better training of maternal health care providers and improvements in birth facilities.
Additionally, the authors say there needs to be guaranteed sustainable financing for maternal health care before and after birth.
They point to a study estimating that between 2013-2015, an extra $72.1 billion is needed to provide high global coverage of quality maternal and newborn health care services.
"These services can be expected to yield a triple benefit of reduced maternal deaths, stillbirths and newborn deaths, and gains for child health and development," the authors note.
WHO's maternal health framework a promising approach
In a commentary summarizing the series, Mary V. Kinney, of global charity Save the Children, and co-authors say the papers highlight two major issues that need to be addressed in order to improve maternal health: the quality of maternal health care and access to it.
The World Health Organization's (WHO) Quality of Care Framework for Maternal and Newborn Health - which has set standards for improving care in maternal and newborn health facilities - is a step in the right direction, say the commentary authors.
"To this end," they add, "a new maternal-newborn health advocacy effort is underway to support implementation of the framework, influence supportive global and national policies and investments, and unify stakeholders in joint action with emphasis on the human rights-based goals of equity, universal coverage, access to quality care services, and dignity and respect for all women and babies."