Prevalence of low birthweight among newborns
The number of live-born neonates with weight less than 2500 grams (g) at birth in a specified reference period is expressed as a percentage of the total number of live births in the same period.
“Live-born” is the the birth of a newborn, irrespective of the duration of gestation, that exhibits any sign of life, such as respiration, heartbeat, umbilical pulsation, or movement of voluntary muscles.
The three main data sources for this indicator are:
- Civil registration and vital statistics (CRVS) systems
- Routinely collected administrative data
- Population-based household surveys
Civil registration and vital statistics systems
A well-functioning and integrated national or subnational CRVS system will universally register and certify vital events, including live births, stillbirths and deaths that occur in the country or administrative area. Birth and death certificates are issued as part of the CRVS system, allowing the compilation, analysis and dissemination of information through vital statistics agencies, including population characteristics (e.g. sex, date of birth or death, place of birth or death, place of usual residence, gestational age at birth and birthweight) and cause-of-death information. Some CRVS systems will also register and certify other important vital events within the population, such as adoptions, marriages and divorces. Data from birth certificates are the preferred data source for this indicator when the system freely and universally records vital events and characteristics (e.g. birthweight); data are recorded in a systematic manner that ensures high data quality for both the public and private health sectors; and across all locations of birth (e.g. health facility or community-based births).
Key source of data: The main source of data for this indicator involves several steps and varies based on the policies and procedures of the national or subnational CRVS or other routine system within health facilities and/or within communities. Declaration of live or stillbirth events are obtained through: (a) forms completed by health personnel at health facilities, or (b) community-based sources, including registration forms submitted directly by the parents of the live or stillbirth. Either paper or electronic forms containing this information are then submitted to the relevant civil authorities and vital statistics agencies, which have the responsibility to officially record the birth event and birth characteristics, such as name, date and place of birth, birthweight, nationality and names of the mother and/or father. At the national or subnational level, the civil authority and vital statistics agency issues birth certificates to formalize the birth registration. If the birth certificate is available and birthweight is available on the certificate, then it is the preferred source for data on birthweight compared to recall.
Indicator definition and calculation: The indicator is calculated as the percentage of live births that weigh less than 2500 g among the total number of live births during a specified reference period. The indicator is calculated as follows:
(Number of live births with weight less than 2500 g at birth in a specified time period / Total number of live births in the same specified time period) x 100
Frequency of measurement: Within CRVS, this indicator is generally monitored at a national or subnational level on an annual basis. The data can be compiled and aggregated subnationally to provide national-level data.
Disaggregation at population level: By sex, gestational age, age of woman at time of delivery, place of birth, place of residence (e.g. urban, rural), subnational administrative units (e.g. districts, provinces, regions), socioeconomic status (e.g. education level, household wealth quintile), and type of reporting source (e.g. health facility, community).
Missing values: Missing values are usually not known.
Routinely collected administrative data
Data from routinely collected and compiled administrative data sources will provide information as recorded in medical charts/records or registers and are entered into national and/or subnational health management information systems (HMIS).
Data from health information systems may collect information on birthweight, including compilation and analyzing the prevalence of LBW (<2500 g) among all newborns born in a health facility. Routinely collected administrative data and health facility statistics are the preferred data source in settings with a high utilization of health facility services and data are recorded in a manner that ensures good data quality for both the public and private health sectors. The compiled data in the national HMIS or District Health Information System (DHIS2) should include data from both public and private health sectors, especially when the private sector is a substantial source of service provision to the population. In settings where utilization of health facilities is not high (e.g. settings with a high prevalence of births occurring at home), data may suffer from incompleteness if information about births occurring outside facilities is not captured. In addition, there are often challenges in accurately measuring the numerator and the denominator when routine HMIS data are used to measure this indicator.
Key source of data: Administrative data sources include health facility and health services data abstracted from obstetric and neonatal medical records, including health services registers. Relevant information is recorded by health personnel within health facilities on paper forms completed by health personnel and/or through an electronic medical record. Data from paper or electronic sources are entered or abstracted into a database or registry and are compiled and analysed within the national and/or subnational HMIS. The ministry of health (MoH) and/or national statistical offices (NSO) are usually responsible for the reporting of this indicator.
Indicator definition and calculation: The indicator is calculated as the percentage of live births that weigh less than 2500 g among the total number of live births in a health facility during a specified reference period. The indicator is calculated as follows:
(Number of live births in health facility with weight less than 2500 g at birth during a specified time period / Total number of live births in health facility in a specified time period) x 100
Frequency of measurement: The indicator can be calculated on an annual basis or may be tracked on a more frequent and ongoing basis (e.g., monthly, quarterly), depending on facility, subnational and national processes for data entry, compilation and analysis. As a guide, the recommended frequency of measurement based on reporting level is outlined below:
- Facility level: Monthly, quarterly, or as needed based on the country and/or facility need
- Subnational (first and second administrative) level: Monthly or quarterly
- National level: Annually (data can be aggregated to provide national-level data).
Disaggregation: By level of facility, location of facility (e.g., urban, rural), gestational age at the time of birth, and maternal age at delivery.
Missing values: Missing values for documented birthweight are assumed to be not weighed.
Population-based household surveys
The main source of data for this indicator has been through population-based household surveys collected through nationally or subnationally representative and structured questionnaires, such as:
• Demographic Health Surveys (DHS) (1)
• Multiple Indicator Cluster Surveys (MICS) (2)
• Reproductive Health Surveys (RHS)
• Other household surveys with a similar methodological design.
Population-based household survey data are the preferred data source in settings with a low utilization of health facility services or where private health sector data are excluded from routinely collected administrative data sources.
Key source of data: Eligible women of reproductive age (15–49 years) are identified in the household survey for inclusion and interviewed using an individual women’s questionnaire. Women are considered eligible for survey interview if they are either usual residents or visitors of the household who stayed there the night before the interview. All eligible and interviewed women between 15 and 49 years old who had a live birth during a specified reference period, typically 2–5 years prior to the time of the interview, are asked “Was (NAME) weighed at birth?”, where “name” refers to the name of the live birth the individual woman had during the same reference period. If the woman responds with an answer of “YES” to this question, she is then asked “How much did (NAME) weigh?” If a birth record or certificate is available, the weight is recorded from the card. If no card is available, the birthweight is recorded based on maternal recall.
The MoH and NSO typically conduct household surveys and compile, analyze and report the results for this indicator in collaboration with the survey program (e.g., DHS, MICS, RHS) and funding agency.
Indicator definition and calculation: Individual women of reproductive age (15–49 years old) are asked about their most recent live birth if the newborn was weighed at birth and how much the newborn weighed – irrespective of the delivery location and the child’s current living status (dead or alive) – and are for the most recent live birth that they had during a specified reference period, which is typically 2–5 years before the time of the survey completion. For this indicator, the recommended reference period is two years preceding the survey interview. The definition is as follows: The percentage of interviewed women aged 15 to 49 years with a live birth in the two (or five) years prior to survey completion whose most recent live birth was to a baby with a reported weight below 2500 g at the time of birth. The indicator is calculated as follows:
(Number of interviewed women [15–49 years old] with a live birth in the 2–5 years prior to survey completion whose most recent live birth was to a baby with a reported weight below 2500 g at the time of birth / Total number of interviewed women [15–49 years old] with a live birth in the 2–5 years prior to survey completion) x 100
Frequency of measurement: Household surveys are typically conducted every 3–5 years.
Disaggregation at population level: Place of delivery, mode of delivery, place of residence (e.g. urban, rural), subnational administrative units (e.g. districts, provinces, regions), sex of live birth, birth order, socioeconomic status (e.g. education level, household wealth quintile), age of woman at the time of delivery, births attended by skilled health personnel, number of antenatal care (ANC) visits and timing of first ANC visit.
Missing values: Included in the distribution as “don’t know” or missing.
A newborn’s weight at birth is a strong indicator of maternal and newborn health and nutrition. Being undernourished in the womb increases the risk of death in the early months and years of a child’s life. Those who survive tend to have impaired immune function and increased risk of disease; they are likely to remain undernourished, with reduced muscle strength, cognitive abilities and IQ throughout their lives. As adults, they suffer from a higher incidence of diabetes and heart disease. WHO defines low birthweight (LBW) among newborns as a birthweight of less than 2500 g. Ideally, this should be the first weight taken within the first hour of life in order to act as the baseline weight for monitoring growth during the postnatal period. Being born with LBW may be due to preterm birth (before 37 weeks’ gestation), restricted fetal (intrauterine) growth, or both underlying causes. LBW is associated with fetal and neonatal mortality; infants born with LBW are more likely to die within the first 28 days of life. LBW is also associated with inhibited growth (6), cognitive/neurodevelopmental morbidity, such as lower IQ (7), and chronic conditions later in life like obesity and diabetes (8).
Accurate monitoring of LBW is challenging, since nearly half of the world’s infants are not weighed at birth (5). Globally, LBW remains a significant public health concern; in 2019, nearly 15% of babies worldwide were born with LBW (2). Currently, the goal is to achieve a 30% reduction in the number of LBW newborns by the year of 2025 (3).
For live births, birthweight should be measured within the first hour of life, before significant postnatal weight loss has occurred. Not being weighed at birth reflects a lack of appropriate newborn care and also presents a challenge to accurately estimating the incidence of LBW (< 2500 g) among newborns, which is associated with newborn health and survival.
This indicator helps public health programs, governments and global health leaders track progress towards targets on reducing prevalence of LBW among newborns, as well as monitor and evaluate the implementation and progress towards effective programming targeted to reducing LBW
Civil registration and vital statistics systems
Collection of vital events such as live births and birthweight that occur either in health facilities or within communities should be part of a well-functioning national and/or subnational CRVS system. However, CRVS systems are either non-existent and/or the complete coverage, accuracy and timeliness of civil registration systems is a major issue in many countries worldwide.
As a result, it is common for births to be undeclared and unregistered, particularly for live birth registrations where neonatal death occurs shortly after birth. This may be due to lack of a legal framework within civil authorities and vital statistics agencies requiring registration for all births, regardless of the outcome. Even in countries with functional CRVS systems and legal frameworks in place, missing or unregistered births still occur due to health professionals and/or parents not knowing about the requirement to register neonatal death and the need to register both the live birth in addition to the death.
Data collected from administrative and other routine data systems
Administrative data may suffer from poor quality such as irregularities in report generation, data duplication and inconsistencies (9). Reporting challenges exist at the facility level given data quality issues, including incomplete, inaccurate and lack of timely data due to insufficient capacity in the health system or inadequate system design. In low-income countries, many babies are born outside of health facility settings and thus are not weighed at birth. As a result, information on birthweight and gestational age at birth are incomplete in many parts of the world, and vary in quality.
Many HMIS databases or registries are event-based and only include women who delivered a birth at a health facility. In some instances, the denominator may include births delivered by women of an unspecified age range and include both live births and stillbirths. These differences in definitions compromise the ability to compare data between countries and across different data sources.
Administrative data should be interpreted with caution in settings where data quality is poor and the percentage of births at public and private sector health facilities is low, or where data from the private health sector are not compiled within the HMIS reporting.
In settings where routine HMIS data lack information on pregnancies and/or births that occur outside the public sector – for example, in homes or in private sector facilities – the total number of births in the HMIS should not serve to estimate the denominator for this indicator. Where data on the total numbers of live births for the entire population for the denominator are unavailable, evaluators can calculate total estimated live births using census data for the total population and crude birth rates in a specified area (total expected live births = estimated population x the total crude birth rate).
Data collected through household surveys
The systematic recording of births in many countries remains a serious challenge. In the absence of reliable CRVS systems or administrative data, household surveys have become the key source of data to monitor levels and trends of births. In most low- and middle-income countries, such surveys represent the sole source of this information.
Women may not be able to accurately recall details around childbirth when data are collected through household surveys (10). There is also a time lag as the recall period is up to 2–5 years before the survey data were collected.
The most commonly reported denominator is the number of women with a live birth in the years preceding the survey, which acts as a proxy for the number of live births. This indicator is prone to survivor bias in that only those women who are alive at the time of the interview would be surveyed and underestimates the total number of live births and the total number of newborns born with LBW.
In these surveys, women are asked about their most recent live birth and when, if at all, their newborn’s health was checked following delivery. This should include both live births that were delivered at home and those delivered in a health facility. However, older iterations of household surveys may only obtain this information for births at home, which should be taken into consideration when reviewing older data.
For more information on this indicator, see the MoNITOR indicator reference sheet developed by the World Health Organization: Who-indicators (srhr.org).
nutrition, newborn (NB), malaria
- The DHS Program [website]. Rockville: ICF International; 2020 (http://www.dhsprogram.com/), accessed 21 October 2020.
- Multiple Indicator Cluster Surveys (MICS) [website]. New York: UNICEF; 2020 (http://mics.unicef.org), accessed 21 October 2020.
- UNICEF, WHO. Low birthweight: country, regional and global estimates. Geneva: World Health Organization; 2004 (https://apps.who.int/iris/bitstream/handle/10665/43184/9280638327.
pdf), accessed 22 October 2020.
- UNICEF–WHO low birthweight estimates: levels and trends 2000–2015. Geneva: World Health Organization; 2019 (https://data.unicef.org/resources/unicef-who-low-birthweight-estimates-levels-and-trends-2000-2015/), accessed 9 November 2020.
- Resolution WHA65.6. Comprehensive implementation plan on maternal, infant and young child nutrition. In: Sixty-fifth World Health Assembly Geneva, 21–26 May 2012. Resolutions and decisions, annexes. Geneva: World Health Organization; 2012 (https://www.who.int/nutrition/topics/WHA65.6_resolution_en.pdf), accessed 22 October 2020.
- Christian P, Lee SE, Donahue AM, Adair LS, Arifeen SE, et al. Risk of childhood undernutrition related to small-for-gestational age and preterm birth in low- and middle-income countries. Int J Epidemiol. 2013;42(5):1340–55 (https://doi.org/10.1093/ije/dyt109), accessed 22 October 2020.
- Gu H, Wang L, Liu L, Luo X, Wang J, et al. A gradient relationship between low birth weight and IQ: a meta-analysis. Sci Rep. 2017;7(1):18035 (https://www.nature.com/articles/s41598-017-18234-9), accessed 22 October 2020.
- Jornayvaz FR, Vollenweider P, Bochud M, Mooser V, Waeber G, Marques-Vidal P. Low birth weight leads to obesity, diabetes and increased leptin levels in adults: the CoLaus study. Cardiovasc Diabetol. 2016;15:73 (https://cardiab.biomedcentral.com/articles/10.1186/s12933-016-0389-2), accessed 22 October 2020.
- Abouzahr C, Boerma T. Health information systems: the foundations of public health. Bull World Health Organ. 2005;83(8):578–83 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2626318/), accessed 22 October 2020.
- Blanc AK, Diaz C, McCarthy KJ, Berdichevsky K. Measuring progress in maternal and newborn health care in Mexico: validating indicators of health system contact and quality of care. BMC Pregnancy Childbirth. 2016;16(1):255 (https://doi.org/10.1186/s12884-016-1047-0), accessed 21 October 2020.