Stillbirth outcome capture and classification in population-based surveys: EN-INDEPTH study

Neonatal mortality during the war in Tigray: a cross-sectional community-based study

BACKGROUND

Neonatal mortality is among the key national and international indicators of health services. The global Sustainable Development Goal target for neonatal mortality is fewer than 12 deaths per 1000 livebirths, by 2030. Neonatal mortality estimates in the 2019 Ethiopian Demographic Health Survey found 25·7 deaths per 1000 livebirths. Subnational surveys specific to Tigray, Ethiopia, reported a neonatal mortality lifetime prevalence of 7·13 deaths. Another government report from the Tigray region estimated a neonatal mortality rate of ten deaths per 1000 livebirths in 2020. Despite the numerous interventions in Ethiopia's Tigray region to achieve the Sustainable Development Goals, the war has disrupted most health services, but the effect on neonatal mortality is unknown. Thus, this study aimed to investigate the magnitude and causes of neonatal mortality during the war in Tigray.

METHODS

A cross-sectional community-based study was conducted in Tigray to evaluate neonatal mortality that occurred from Nov 4, 2020, to May 30, 2022. Among the 31 districts, 121 tabias were selected using computer-generated random sampling, and 189 087 households were visited. We adopted a validated WHO 2022 verbal autopsy tool, and data were collected using an interviewer-administrated Open Data Kit. In the absence of the mother, other respondents to the verbal autopsy interview were household members aged 18 years and older who provided care during the final illness that led to death.

FINDINGS

29 761 livebirths were recorded during the screening of 189 087 households. Verbal autopsy was administered for 1158 households with neonatal deaths. 317 neonates were stillborn, and 841 neonatal deaths were recorded with the WHO 2022 verbal autopsy tool from Nov 4, 2020, to May 30, 2022, in 31 districts. The neonatal mortality rate was 28·2 deaths per 1000 livebirths. 476 (57%) of the 841 neonatal deaths occurred at home and 296 (35%) in health facilities. A high rate of neonatal deaths was reported in rural districts (80% [673 of 841]) compared with urban districts (20% [168 of 841]), and 663 (79%) deaths occurred during the early neonatal period, in the first week of life (0-6 days). The leading causes of neonatal death were asphyxia (35% [291 of 834]), prematurity (30% [247 of 834]), and infection (12% [104 of 834]). Asphyxia (37% [246 of 663]) and infection (28% [50 of 178]) were the leading causes of death for early and late neonatal period deaths, respectively.

INTERPRETATION

Neonatal mortality in Tigray is high due to preventable causes. An urgent response is needed to prevent the high number of neonatal deaths associated with the depleted health resources and services resulting from the war, and to achieve the Sustainable Development Goal on neonatal mortality.

FUNDING

UNICEF and United Nations Fund for Population Activities.

TRANSLATION

For the Tigrigna translation of the abstract see Supplementary Materials section.

Exploring women's interpretations of survey questions on pregnancy and pregnancy outcomes: cognitive interviews in Iganga Mayuge, Uganda

BACKGROUND

In 2021, Uganda's neonatal mortality rate was approximately 19 deaths per 1000 live births, with an estimated stillbirth rate of 15.1 per 1000 total births. Data are critical for indicating areas where deaths occur and why, hence driving improvements. Many countries rely on surveys like Demographic and Health Surveys (DHS), which face challenges with respondents' misinterpretation of questions. However, little is documented about this in Uganda. Cognitive interviews aim to improve questionnaires and assess participants' comprehension of items. Through cognitive interviews we explored women's interpretations of questions on pregnancy and pregnancy outcomes.

METHODS

In November 2021, we conducted cognitive interviews with 20 women in Iganga Mayuge health and demographic surveillance system site in eastern Uganda. We adapted the reproductive section of the DHS VIII women's questionnaire, purposively selected questions and used concurrent verbal probing. Participants had secondary school education and were English speaking. Cognition was measured through comparing instructions in the DHS interviewers' manual to participants' responses and researcher's knowledge. A qualitative descriptive approach to analysis was undertaken.

RESULTS

We report findings under the cognitive aspect of comprehension. Some questions were correctly understood, especially those with less technical terms or without multiple sections. Most participants struggled with questions asking whether the woman has her living biological children residing with her or not. Indeed, some thought it referred to how many living children they had. There were comprehension difficulties with long questions like 210 that asks about miscarriages, newborn deaths, and stillbirths together. Participants had varying meanings for miscarriages, while many misinterpreted stillbirth, not linking it to gestational age. Furthermore, even amongst educated women some survey questions were misunderstood.

CONCLUSIONS

Population surveys may misclassify, over or under report events around pregnancy and pregnancy outcomes. Interviewers should begin with a standard definition of key terms and ensure respondents understand these. Questions can be simplified through breaking up long sentences, while interviewer training should be modified to ensure they thoroughly understand key terms. We recommend cognitive interviews while developing survey tools, beyond basic pre-testing. Improving respondents' comprehension and thus response accuracy will increase reporting and data quality.

Maternal interventions to decrease stillbirths and neonatal mortality in Tanzania: evidence from the 2017-18 cross-sectional Tanzania verbal and social autopsy study

BACKGROUND

Reduction of Tanzania's neonatal mortality rate has lagged behind that for all under-fives, and perinatal mortality has remained stagnant over the past two decades. We conducted a national verbal and social autopsy (VASA) study to estimate the causes and social determinants of stillbirths and neonatal deaths with the aim of identifying relevant health care and social interventions.

METHODS

A VASA interview was conducted of all stillbirths and neonatal deaths in the prior 5 years identified by the 2015-16 Tanzania Demographic and Health Survey. We evaluated associations of maternal complications with antepartum and intrapartum stillbirth and leading causes of neonatal death; conducted descriptive analyses of antenatal (ANC) and delivery care and mothers' careseeking for complications; and developed logistic regression models to examine factors associated with delivery place and mode.

RESULTS

There were 204 stillbirths, with 185 able to be classified as antepartum (88 [47.5%]) or intrapartum (97 [52.5%]), and 228 neonatal deaths. Women with an intrapartum stillbirth were 6.5% (adjusted odds ratio (aOR) = 1.065, 95% confidence interval (CI) 1.002, 1.132) more likely to have a C-section for every additional hour before delivery after reaching the birth attendant. Antepartum hemorrhage (APH), maternal anemia, and premature rupture of membranes (PROM) were significantly positively associated with early neonatal mortality due to preterm delivery, intrapartum-related events and serious infection, respectively. While half to two-thirds of mothers made four or more ANC visits (ANC4+), a third or fewer received quality ANC (Q-ANC). Women with a complication were more likely to deliver at hospital only if they received Q-ANC (neonates: aOR = 4.5, 95% CI 1.6, 12.3) or ANC4+ (stillbirths: aOR = 11.8, 95% CI 3.6, 38.0). Nevertheless, urban residence was the strongest predictor of hospital delivery.

CONCLUSIONS

While Q-ANC and ANC4 + boosted hospital delivery among women with a complication, attendance was low and the quality of care is critical. Quality improvement efforts in urban and rural areas should focus on early detection and management of APH, maternal anemia, PROM, and prolonged labor, and on newborn resuscitation.

Psychosocial effects of adverse pregnancy outcomes and their influence on reporting pregnancy loss during surveys and surveillance: narratives from Uganda

BACKGROUND

In 2021, Uganda had an estimated 25,855 stillbirths and 32,037 newborn deaths. Many Adverse Pregnancy Outcomes (APOs) go unreported despite causing profound grief and other mental health effects. This study explored psychosocial effects of APOs and their influence on reporting these events during surveys and surveillance settings in Uganda.

METHODS

A qualitative cross-sectional study was conducted in September 2021 in Iganga Mayuge health and demographic surveillance system site, eastern Uganda. Narratives were held with 44 women who had experienced an APO (miscarriage, stillbirth or neonatal death) and 7 men whose spouses had undergone the same. Respondents were purposively selected and the sample size premised on the need for diverse respondents. Reflexive thematic analysis was undertaken, supported by NVivo software.

RESULTS

60.8% of respondents had experienced neonatal deaths, 27.4% stillbirths, 11.8% miscarriages and almost half had multiple APOs. Theme one on psychosocial effects showed that both women and men suffered disbelief, depression, shame and thoughts of self-harm. In theme two on reactions to interviews, most respondents were reminded about their loss. Indeed, some women cried and a few requested termination of the interview. However, many said they eventually felt better, especially where interviewers comforted and advised them. In theme three about why people consent to such interviews, it was due to the respondents' need for sensitization on causes of pregnancy loss and danger signs, plus the expectation that the interview would lead to improved health services. Theme four on suggestions for improving interviews highlighted respondents' requests for a comforting and encouraging approach by interviewers.

CONCLUSION

Psychosocial effects of APOs may influence respondents' interest and ability to effectively engage in an interview. Findings suggest that a multi-pronged approach, including interviewer training in identifying and dealing responsively with grieving respondents, and meeting needs for health information and professional counselling could improve reporting of APOs in surveys and surveillance settings. More so, participants need to understand the purpose of the interview and have realistic expectations.

Maternal mortality, stillbirths, and neonatal mortality: a transition model based on analyses of 151 countries

BACKGROUND

Maternal mortality, stillbirths, and neonatal mortality account for almost 5 million deaths a year and are often analysed separately, despite having overlapping causes and interventions. We propose a comprehensive five-phase mortality transition model to improve analyses of progress and inform strategic planning.

METHODS

In this empirical data-driven study to develop a model transition, we used UN estimates for 151 countries to assess changes in maternal mortality, stillbirths, and neonatal deaths. On the basis of ratios of maternal to stillbirth and neonatal mortality, we identified five phases of transition, in which phase 1 has the highest mortality and phase 5 has the lowest. We used global databases to examine phase-specific characteristics during 2000-20 for causes of death, fertility rates, abortion policies, health workforce and financing, and socioeconomic indicators. We analysed 326 national surveys to assess service coverage and inequalities by transition phase.

FINDINGS

Among 116 countries in phases 1 to 4 in 2000, 73 (63%) progressed at least one phase by 2020, six advanced two phases, and three regressed. The ratio of stillbirth and neonatal deaths to maternal deaths increased from less than 10 in phase 1 to well over 50 in phase 4 and phase 5. Progression was associated with a declining proportion of deaths caused by infectious diseases and peripartum complications, declining total and adolescent fertility rates, changes in health-workforce densities and skills mix (ie, ratio of nurses or midwives to physicians) from phase 3 onwards, increasing per-capita health spending, and reducing shares of out-of-pocket health expenditures. From phase 1 to 5, the median coverage of first antenatal care visits increased from 66% to 98%, four or more antenatal care visits from 44% to 94%, institutional births from 36% to 99%, and caesarean section rates from 2% to 25%. The transition out of high-mortality phases involved a major increase in institutional births, primarily in lower-level health facilities, whereas subsequent progress was characterised by rapid increases in hospital births. Wealth-related inequalities reduced strongly for institutional birth coverage from phase 3 onwards.

INTERPRETATION

The five-phase maternal mortality, stillbirth, and neonatal mortality transition model can be used to benchmark the current indicators in comparison to typical patterns in the transition at national or sub-national level, identify outliers to better assess drivers of progress, and inform strategic planning and investments towards Sustainable Development Goal targets. It can also facilitate programming for integrated strategies to end preventable maternal mortality and neonatal mortality and stillbirths.

FUNDING

Bill & Melinda Gates Foundation.

Understanding clinical outcome measures reported in HIV pregnancy studies involving antiretroviral-naive and antiretroviral-experienced women

HIV infection is a clinically significant public health disease and contributes to increased risk of maternal and fetal morbidity and mortality. HIV pregnancy studies use outcome measures as metrics to show how people with HIV feel, function, or survive. These endpoints are crucial for tracking the evolution of HIV illness over time, assessing the effectiveness of antiretroviral therapy (ART), and comparing outcomes across studies. Although the need for ideal outcome measures is widely acknowledged, selecting acceptable outcome measures for these HIV pregnancy studies can be challenging. We discuss the many outcome measures that have been implemented over time to assess HIV in pregnancy studies, their benefits, and drawbacks. Finally, we offer suggestions for improving the reporting of outcome measures in HIV in pregnancy studies. Medical professionals can best care for pregnant women living with HIV receiving ART by having a thorough understanding of these outcome metrics.

Neonatal and perinatal mortality in the urban continuum: a geospatial analysis of the household survey, satellite imagery and travel time data in Tanzania

INTRODUCTION

Recent studies suggest that the urban advantage of lower neonatal mortality in urban compared with rural areas may be reversing, but methodological challenges include misclassification of neonatal deaths and stillbirths, and oversimplification of the variation in urban environments. We address these challenges and assess the association between urban residence and neonatal/perinatal mortality in Tanzania.

METHODS

The Tanzania Demographic and Health Survey (DHS) 2015-2016 was used to assess birth outcomes for 8915 pregnancies among 6156 women of reproductive age, by urban or rural categorisation in the DHS and based on satellite imagery. The coordinates of 527 DHS clusters were spatially overlaid with the 2015 Global Human Settlement Layer, showing the degree of urbanisation based on built environment and population density. A three-category urbanicity measure (core urban, semi-urban and rural) was defined and compared with the binary DHS measure. Travel time to the nearest hospital was modelled using least-cost path algorithm for each cluster. Bivariate and multilevel multivariable logistic regression models were constructed to explore associations between urbanicity and neonatal/perinatal deaths.

RESULTS

Both neonatal and perinatal mortality rates were highest in core urban and lowest in rural clusters. Bivariate models showed higher odds of neonatal death (OR=1.85; 95% CI 1.12 to 3.08) and perinatal death (OR=1.60; 95% CI 1.12 to 2.30) in core urban compared with rural clusters. In multivariable models, these associations had the same direction and size, but were no longer statistically significant. Travel time to the nearest hospital was not associated with neonatal or perinatal mortality.

CONCLUSION

Addressing high rates of neonatal and perinatal mortality in densely populated urban areas is critical for Tanzania to meet national and global reduction targets. Urban populations are diverse, and certain neighbourhoods or subgroups may be disproportionately affected by poor birth outcomes. Research must capture, understand and minimise risks specific to urban settings.

Birth weight and gestational age distributions in a rural Kenyan population

BACKGROUND

With the increased availability of access to prenatal ultrasound in low/middle-income countries, there is opportunity to better characterize the association between fetal growth and birth weight across global settings. This is important, as fetal growth curves and birthweight charts are often used as proxy health indicators. As part of a randomized control trial, in which ultrasonography was utilized to establish accurate gestational age of pregnancies, we explored the association between gestational age and birthweight among a cohort in Western Kenya, then compared our results to data reported by the INTERGROWTH-21st study.

METHODS

This study was conducted in 8 geographical clusters across 3 counties in Western Kenya. Eligible subjects were nulliparous women carrying singleton pregnancies. An early ultrasound was performed between 6 + 0/7 and 13 + 6/7 weeks gestational age. At birth, infants were weighed on platform scales provided either by the study team (community births), or the Government of Kenya (public health facilities). The 10th, 25th, median, 75th, and 90th BW percentiles for 36 to 42 weeks gestation were determined; resulting percentile points were plotted, and curves determined using a cubic spline technique. A signed rank test was used to quantify the comparison of the percentiles generated in the rural Kenyan sample with those of the INTERGROWTH-21st study.

RESULTS

A total of 1291 infants (of 1408 pregnant women randomized) were included. Ninety-three infants did not have a measured birth weight. The majority of these were due to miscarriage (n = 49) or stillbirth (n = 27). No significant differences were found between subjects who were lost to follow-up. Signed rank comparisons of the observed median of the Western Kenya data at 10th, 50th, and 90th birthweight percentiles, as compared to medians reported in the INTERGROWTH-21st distributions, revealed close alignment between the two datasets, with significant differences at 36 and 37 weeks. Limitations of the current study include small sample size, and detection of potential digit preference bias.

CONCLUSIONS

A comparison of birthweight percentiles by gestational age estimation, among a sample of infants from rural Kenya, revealed slight differences as compared to those from the global population (INTERGROWTH-21st).

TRIAL REGISTRATION

This is a single site sub-study of data collected in conjunction with the Aspirin Supplementation for Pregnancy Indicated Risk Reduction In Nulliparas (ASPIRIN) Trial, which is listed at  ClinicalTrials.gov ,  NCT02409680 (07/04/2015).

Retrospective analysis of stillbirth and induced termination of pregnancies: Factors affecting determination

OBJECTIVE

The aim of this study was to identify the factors and frequencies of induced termination of pregnancies.

MATERIALS AND METHODS

This is a retrospective study of 488 terminations of pregnancies (TOPs) between January 2011 and December 2021 to demonstrate the factors affecting the decision to terminate the pregnancy. All cases had been hospitalized to manage the induction of labor. Methods included serial multiple laminaria dilation of the cervix and administration of a cervical misoprostol suppository. After induction of labor, the subject may experience amniotomy, instrumental evacuation of the uterus, and even hysterotomy. Pre-procedure counseling included an agreement to share medical records (paper-based and electronic). We verified the indications for all patients seeking TOPs. All cases were performed according to known diagnostic classifications and divided into seven groups for analysis.

RESULTS

The patient ages ranged from 12 to 46 years. The median maternal age was 34 years [interquartile range (IQR) 30, 37]; 52.2% had at least one prior delivery. The pre-procedure diagnosis was divided into seven groups including the following: chromosomal and genetic abnormalities (146/488, 29.9%), no intrauterine heartbeats (126/488, 25.8%), structural anomalies (84/488, 17.2%), elective termination (56/488, 11.5%), preterm premature rupture of membranes (PPROM) (42/488, 8.6%), cervical incompetence (32/488, 6.6%), and other conditions (2/488, 0.4%). After excluding elective terminations, the eleven-year rate of fetal death and stillbirth to births did not show significant changes from 2011 to 2021.

CONCLUSIONS

Knowing the factors underlying the decision to induce intrauterine fetal death (IUFD) including reasons for objecting to pregnancy are important for obstetricians-they can offer better planning and medical counseling. It is important to educate all women about family planning to prevent large numbers of unwanted and unsafe pregnancy terminations.

Stillbirths including intrapartum timing: EN-BIRTH multi-country validation study

BACKGROUND

An estimated >2 million babies stillborn around the world each year lack visibility. Low- and middle-income countries carry 84% of the burden yet have the least data. Most births are now in facilities, hence routine register-recording presents an opportunity to improve counting of stillbirths, but research is limited, particularly regarding accuracy. This paper evaluates register-recorded measurement of hospital stillbirths, classification accuracy, and barriers and enablers to routine recording.

METHODS

The EN-BIRTH mixed-methods, observational study took place in five hospitals in Bangladesh, Nepal and Tanzania (2017-2018). Clinical observers collected time-stamped data on perinatal care and birth outcomes as gold standard. To assess accuracy of routine register-recorded stillbirth rates, we compared birth outcomes recorded in labour ward registers to observation data. We calculated absolute rate differences and individual-level validation metrics (sensitivity, specificity, percent agreement). We assessed misclassification of stillbirths with neonatal deaths. To examine stillbirth appearance (fresh/macerated) as a proxy for timing of death, we compared appearance to observed timing of intrauterine death based on heart rate at admission.

RESULTS

23,072 births were observed including 550 stillbirths. Register-recorded completeness of birth outcomes was > 90%. The observed study stillbirth rate ranged from 3.8 (95%CI = 2.0,7.0) to 50.3 (95%CI = 43.6,58.0)/1000 total births and was under-estimated in routine registers by 1.1 to 7.3 /1000 total births (register: observed ratio 0.9-0.7). Specificity of register-recorded birth outcomes was > 99% and sensitivity varied between hospitals, ranging from 77.7-86.1%. Percent agreement between observer-assessed birth outcome and register-recorded birth outcome was very high across all hospitals and all modes of birth (> 98%). Fresh or macerated stillbirth appearance was a poor proxy for timing of stillbirth. While there were similar numbers of stillbirths misclassified as neonatal deaths (17/430) and neonatal deaths misclassified as stillbirths (21/36), neonatal deaths were proportionately more likely to be misclassified as stillbirths (58.3% vs 4.0%). Enablers to more accurate register-recording of birth outcome included supervision and data use.

CONCLUSIONS

Our results show these routine registers accurately recorded stillbirths. Fresh/macerated appearance was a poor proxy for intrapartum stillbirths, hence more focus on measuring fetal heart rate is crucial to classification and importantly reduction in these preventable deaths.

Stillbirth maternity care measurement and associated factors in population-based surveys: EN-INDEPTH study

BACKGROUND

Household surveys remain important sources of maternal and child health data, but until now, standard surveys such as Demographic and Health Surveys (DHS) have not collected information on maternity care for women who have experienced a stillbirth. Thus, nationally representative data are lacking to inform programmes to address the millions of stillbirths which occur annually.

METHODS

The EN-INDEPTH population-based survey of women of reproductive age was undertaken in five Health and Demographic Surveillance System sites in Bangladesh, Ethiopia, Ghana, Guinea-Bissau and Uganda (2017-2018). All women answered a full birth history with additional questions on pregnancy losses (FBH+) or full pregnancy history (FPH). A sub-sample, including all women reporting a recent stillbirth or neonatal death, was asked additional maternity care questions. These were evaluated using descriptive measures. Associations between stillbirth and maternal socio-demographic characteristics, babies' characteristics and maternity care use were assessed using a weighted logistic regression model for women in the FBH+ group.

RESULTS

A total of 15,591 women reporting a birth since 1 January 2012 answered maternity care questions. Completeness was very high (> 99%), with similar proportions of responses for both live and stillbirths. Amongst the 14,991 births in the FBH+ group, poorer wealth status, higher parity, large perceived baby size-at-birth, preterm or post-term birth, birth in a government hospital compared to other locations and vaginal birth were associated with increased risk of stillbirth after adjusting for potential confounding factors. Regarding association with reported postnatal care, women with a stillbirth were more likely to report hospital stays of > 1 day. However, women with a stillbirth were less likely to report having received a postnatal check compared to those with a live birth.

CONCLUSIONS

Women who had experienced stillbirth were able to respond to questions about pregnancy and birth, and we found no reason to omit questions to these women in household surveys. Our analysis identified several potentially modifiable factors associated with stillbirth, adding to the evidence-base for policy and action in low- and middle-income contexts. Including these questions in DHS-8 would lead to increased availability of population-level data to inform action to end preventable stillbirths.

Birthweight data completeness and quality in population-based surveys: EN-INDEPTH study

BACKGROUND

Low birthweight (< 2500 g) is an important marker of maternal health and is associated with neonatal mortality, long-term development and chronic diseases. Household surveys remain an important source of population-based birthweight information, notably Demographic and Health Surveys (DHS) and UNICEF's Multiple Indicator Cluster Surveys (MICS); however, data quality concerns remain. Few studies have addressed how to close these gaps in surveys.

METHODS

The EN-INDEPTH population-based survey of 69,176 women was undertaken in five Health and Demographic Surveillance System sites (Matlab-Bangladesh, Dabat-Ethiopia, Kintampo-Ghana, Bandim-Guinea-Bissau, IgangaMayuge-Uganda). Responses to existing DHS/MICS birthweight questions on 14,411 livebirths were analysed and estimated adjusted odds ratios (aORs) associated with reporting weighing, birthweight and heaping reported. Twenty-eight focus group discussions with women and interviewers explored barriers and enablers to reporting birthweight.

RESULTS

Almost all women provided responses to birthweight survey questions, taking on average 0.2 min to answer. Of all babies, 62.4% were weighed at birth, 53.8% reported birthweight and 21.1% provided health cards with recorded birthweight. High levels of heterogeneity were observed between sites. Home births and neonatal deaths were less likely to be weighed at birth (home births aOR 0.03(95%CI 0.02-0.03), neonatal deaths (aOR 0.19(95%CI 0.16-0.24)), and when weighed, actual birthweight was less likely to be known (aOR 0.44(95%CI 0.33-0.58), aOR 0.30(95%CI 0.22-0.41)) compared to facility births and post-neonatal survivors. Increased levels of maternal education were associated with increases in reporting weighing and knowing birthweight. Half of recorded birthweights were heaped on multiples of 500 g. Heaping was more common in IgangaMayuge (aOR 14.91(95%CI 11.37-19.55) and Dabat (aOR 14.25(95%CI 10.13-20.3) compared to Bandim. Recalled birthweights were more heaped than those recorded by card (aOR 2.59(95%CI 2.11-3.19)). A gap analysis showed large missed opportunity between facility birth and known birthweight, especially for neonatal deaths. Qualitative data suggested that knowing their baby's weight was perceived as valuable by women in all sites, but lack of measurement and poor communication, alongside social perceptions and spiritual beliefs surrounding birthweight, impacted women's ability to report birthweight.

CONCLUSIONS

Substantial data gaps remain for birthweight data in household surveys, even amongst facility births. Improving the accuracy and recording of birthweights, and better communication with women, for example using health cards, could improve survey birthweight data availability and quality.