Maternal Education and Stillbirth: Estimating Gestational-age-specific and Cause-specific Associations

Mediators affecting the higher risk of stillbirth among foreign-born women in Sweden: A nationwide cohort study

INTRODUCTION

In Sweden, a higher incidence of stillbirth has been observed among women originating from sub-Saharan Africa and the Middle East. In this nationwide cohort of more than 2 million births, we assessed the risk factors for stillbirth among foreign-born women with the aim of understanding which mediators have the largest impact on the elevated risk of stillbirth.

MATERIAL AND METHODS

This was a nationwide cohort study in Sweden including 2 300 391 births between 2000 and 2021. Data from the National Medical Birth Register were linked to data from Statistics Sweden using the personal identity number of the mother. Differences in maternal characteristics were analyzed between women divided into groups based on maternal country of origin. Logistic regression models were made with a forward selection strategy adjusting for potential mediators on the causal pathway from maternal country of origin to stillbirth.

RESULTS

A significantly higher risk of stillbirth was observed among women originating from Eastern Europe, the Middle East/Northern Africa, sub-Saharan Africa, and Asia, with the highest risk observed in women originating from sub-Saharan Africa (OR 2.40, 95% CI 2.16-2.67, p-value <0.001). After adjusting for maternal risk factors, fetuses small for gestational age, and socioeconomic factors, women originating from sub-Saharan Africa still had a significantly higher risk of stillbirth (OR 1.28, 95% CI 1.14-1.44, p-value <0.001) compared to women originating from Sweden. The risk among the other groups of foreign-born women was, however, equal to the risk among women originating from Sweden. Mediation analysis showed that 31.2% of the effect of sub-Saharan origin on stillbirth was mediated through fetuses small for gestational age, 12.7% through educational level, and 16.9% through disposable income level.

CONCLUSIONS

In Sweden, women originating from sub-Saharan Africa face a significantly higher risk of stillbirth even after adjusting for known risk factors. The higher risk is partly mediated by giving birth to fetuses small for gestational age and socioeconomic factors, but it cannot be explained altogether. This disparity may stem from multifactorial causes, including how risk populations utilize health care during pregnancies. Further studies are needed to find preventive measures to decrease the disparity.

Predictors of stillbirth at Tema General Hospital: a registry-based retrospective study

BACKGROUND

In 2015, the global incidence of stillbirths reached 2.6 million, equating to more than 7,178 deaths daily. The stillbirth rate in Ghana during this period was recorded at 22.7 per 1,000 births. While extensive research has been undertaken in high-income countries to document stillbirth rates and elucidate the associated risk factors, there is a notable paucity of similar studies in Ghana. This study therefore determined the predictors of stillbirth in a Ghanaian referral hospital.

METHODS

We conducted a facility-based 1:1 unmatched case-control study comparing data of women who had stillbirths to those who had live births at the Tema General Hospital in 2019. Data were obtained from the hospital records using a data extraction form that was specifically designed for this purpose. We extracted and entered data into Microsoft Excel 2013, cleaned, and analyzed using STATA 15. Frequency and percentage distributions were used to describe the characteristics of respondents. Bivariate and logistic regression analyses were carried out to examine predictors of stillbirth.

RESULTS

Of 552 mothers included in the study, the mean age of mothers with and without stillbirths was 31.4 (SD ± 6.1) years, and 28.8 (SD ± 6.0) years respectively. We identified Mothers aged 40 years and older [aOR = 5.5; (95% CI 1.1-26.9)], Maternal employment [aOR = 2.5; (95% CI = 1.2-5.3)], Caesarean section [aOR = 1.9; (95% CI = 1.2-2.9)], Infants with low birth weight [aOR = 8.7; (95% CI = 5.2- 14.7)], Hypertensive mothers [aOR = 1.9; (95% CI = 1.2-2.8)] to significantly increased likelihood of stillbirth. Primary education [aOR = 0.4; (95% CI = 0.2-0.8)], Tertiary education [aOR = 0.2; (95% CI = 0.1-0.5)], Mothers who attended four or more antenatal care (ANC) [aOR = 0.6; (95% CI = 0.3-0.9)] significantly lower odds of experiencing stillbirth.

CONCLUSION

A combination of socio-demographic, maternal, and foetal variables predicted stillbirth at Tema General Hospital in 2019. Recommendations for improving birth outcomes at the hospital entail persistent community awareness initiatives targeting the impact of pivotal risk factors, timely stratification of pregnancies based on risk assessment, and the establishment of specialized Antenatal Care (ANC) services tailored for high-risk cohorts.

Prevalence and associated factors of stillbirth among women at extreme ages of reproductive life in Sub-Saharan Africa: a multilevel analysis of the recent demographic and health survey

BACKGROUND

Stillbirth is one of the biggest adverse pregnancy outcomes in countries with low and middle incomes. If current trends continue, 15.9 million babies will be stillborn; nearly half of these (7.7 million, or 48%) will occur in sub-Saharan Africa. Although stillbirth is one of the health care indicators, its prevalence and determinates are not well studied in low- and middle-income countries (LMIC). Therefore, this study aims to assess the prevalence and associated factors of stillbirth among people at extreme ages of reproductive life in Sub-Saharan Africa.

METHODS

Data from the most recent Demographic and Health Surveys, which covered 23 Sub-Saharan African countries from 2015 to 2022, were used for secondary data analysis. The study used a total of 76,451 women. STATA 14 was used to analyze the data. The associated factors of stillbirth were determined using a multilevel mixed-effects logistic retrogression model. Significant factors associated with stillbirth were declared significant at p- value < 0.05.

RESULTS

The prevalence of stillbirth in Sub-Saharan Africa was 6.18% (95% CI: 6.01, 6.35). Higher odds of stillbirth were observed among women at advanced age (35-49 years) (AOR = 3.72, 95% CI: 2.57, 5.41), those who consumed alcohol during pregnancy (AOR = 1.58, 95% CI: 1.24, 2.00), and those who underwent cesarean section delivery (AOR = 1.23, 95% CI: 1.11, 1.37). Additionally, rural residence (AOR = 1.11, 95% CI: 1.01, 1.23), high community levels of illiteracy (AOR = 1.19, 95% CI: 1.07, 1.32), and residing in South sub-Saharan Africa (AOR = 1.19, 95% CI: 1.03, 1.38) were positively associated with stillbirth.

CONCLUSIONS

This study concludes that stillbirth among women at extreme ages of reproductive life is high compared to the UNICEF 2022 report. The study identified that both individual and community-level variables were associated factors of stillbirth. Therefore, the ministries of health in Sub-Saharan African countries should give attention to those women at the extreme ages of reproductive life and to women from rural areas while designing policies and strategies targeting reducing stillbirth rates.

Intrauterine Fetal Death in Term Pregnancy-A Single Tertiary Clinic Study

INTRODUCTION

Intrauterine fetal death (IUFD) is defined as death of the fetus after the 20th week of gestation. Despite regular monitoring the incidence of IUFD remains high. This study aims to assess the incidence and maternal conditions associated with IUFD over term pregnancies in a twelve-year period.

MATERIALS AND METHODS

A retrospective descriptive study was conducted on a population of women in whom IUFD was diagnosed in a term pregnancy during the period from January 2010 to December 2022. The study was at the Clinic for Obstetrics and Gynecology, University Clinic Centre of Serbia. The analyses included the number of deliveries, live births, and stillbirths, as well as maternal, fetal, and placental conditions associated with the risk of IUDF. The statistical analysis involved descriptive statistical methods and one sample proportion.

RESULTS

The average age of the patients was 30 years. Most patients had secondary and higher education, and 70% of patients had regular pregnancy monitoring; 53.33% were primiparous and pregnancies occurred spontaneously. IUFD mainly occurred in the 39th week of gestation. In total, 38.3% had one to two associated diseases, 5% more than three, and 58.33% were healthy. Recurrence of IUFD was reported by 10% of patients, while 8.33% had a history of spontaneous abortion. Over 80% of placental histopathological findings indicated some pathology (e.g., infarction, infections, placental abruption).

CONCLUSIONS

The most significant risk factors for IUFD in term pregnancies in our population during the study period were hypertensive syndrome in pregnancy, obesity and gestational diabetes. Pathological findings on the placenta were more common in our study group than is usually reported with infractions of placental tissue being the most common, even in healthy women.

Placental Pathology and Maternal Risk Factors for Stillbirth: A Case-Control Study

Background Fetal death is the delivery of a fetus with no sign of life, as indicated by the absence of breathing, heartbeat, pulsation of the umbilical cord, or definite movement of voluntary muscles. Nearly 2.6 million stillbirths are estimated to occur worldwide every year. Almost all of these (98%) stillbirths occur in low- and middle-income countries. About one-sixth of the stillbirths globally were recorded in India in 2019, making it the most burdened country in the world. In light of this, we conducted a study to identify the placental pathologies and maternal factors associated with stillbirth. Methodology A case-control study was conducted at the Department of Obstetrics & Gynecology, Veer Surendra Sai Institute of Medical Sciences and Research (VIMSAR), from June 2022 to May 2023. Cases included pregnant women with a gestational age of 28 weeks or more who delivered a stillbirth infant at VIMSAR, and controls included gestational age-matched deliveries with live birth. Consent to participate in the study was obtained before enrolment. The final sample size was 79 cases and controls. The chi-square test was performed for bivariate analysis, and logistic regression was used for multivariate analysis. Results In our study, we found a significant association between maternal age of more than 30 years (odds ratio (OR) = 3.01, 95% confidence interval (CI) = 1.91-4.22, p = 0.012), maternal education (with up to the primary level or less: OR = 6.19, 95% CI = 2.92-7.87, p = 0.012), history of addiction (tobacco chewing: OR = 5.58, 95% CI = 3.71-7.11, p = 0.03), and the number of antenatal visits (no visit: OR = 6.87, 95% CI = 2.91-7.79, p = 0.019) with an increased risk of stillbirth. Among the obstetrical complications, pre-eclampsia/eclampsia (OR = 3.87, 95% CI = 1.98-5.11, p = 0.001), premature rupture of membranes (PROM)/preterm premature rupture of the membranes (PPROM) (OR = 2.49, 95% CI = 1.31-3.91, p = 0.03) and antepartum hemorrhage (APH) (OR = 2.66, 95% CI = 1.65-3.58, p = 0.02) were found to be significantly related with stillbirth. Among placental pathologies, uteroplacental vascular pathology (OR = 7.39, 95% CI = 3.01-8.97), acute chorioamnionitis (OR = 3.35, 95% CI = 2.11-5.21), chronic inflammation (OR = 2.33, 95% CI = 1.91 4.17), calcific changes (OR = 4.46, 95% CI = 2.56-6.01), and retroplacental clots (OR = 9.95, 95% CI = 4.39-11.71) were associated with stillbirth. Conclusions In our study, advanced maternal age, absence of antenatal visits, low level of education, tobacco addiction, pre-eclampsia/eclampsia, APH, and PROM in pregnancy were the major risk factors associated with stillbirth. Uteroplacental vascular pathology, chorioamnionitis, chronic inflammation, retroplacental hematoma, and calcific changes were the most significant placental lesions associated with stillbirth.

Trends and risk factors of stillbirth among women of reproductive age in Pakistan: A multivariate decomposition analysis

Background

Every year, 2 million babies are stillborn in the world. Globally, there has been a decline in the stillbirth rate of 2%. Despite advancements in prenatal care and the implementation of new medical technologies, the incidence of early stillbirths remains unchanged. A slight decrease in the rate of late-term stillbirth has been observed. Pakistan ranked third in South Asia for having the highest stillbirth rate. Compared to its neighbors and other developing nations, Pakistan has shown a lack of progress in reducing maternal and neonatal fatalities. Therefore, the purpose of this study is to use a multivariate decomposition analysis to examine the trends and factors that have contributed to the change in the stillbirth rate over time.

Methods

To conduct this study, we used a secondary data analysis approach and analyzed data from the Pakistan Demographic and Health Survey (PDHS) of 2012-2013 and 2017-2018). For the analysis, a total sample of 15,068 births in 2017-2018 and 13,558 births in the PDHS from 2012 to 2013 were taken into account. Using the MVDCMP function within STATA version 15 statistical software, a logit-based multivariate decomposition model was fitted to determine the variables that influence the change in stillbirth. The current study used two cross-sectional surveys to identify important risk factors for stillbirths.

Results

Over the past 5 years, Pakistan's stillbirth rate has risen from 3.98 to 5.75%. According to the total multivariate decomposition analysis, the change in coefficient (change in the effect of attributes) accounted for 81.17% of the overall change in the proportion of stillbirths. In contrast, the change in endowment was not statistically significant. Changes in maternal education, individual and community-level wealth status, and mode of delivery all significantly impacted the rate of stillbirths over time.

Conclusion

Stillbirths increased in Pakistan from 2012 to 2017. Stillbirths are observed more frequently for women residing in Punjab, Sindh, and rural areas. A major concern that is directly related to the prevalence of stillbirths in Pakistan is the lack of accessible, affordable, and high-quality maternal healthcare facilities. Older, overweight, and uneducated women are more likely to have stillbirths than women who deliver vaginally. High parity and short birth intervals also accelerated the rate of stillbirths. An effective remedy to control stillbirths is the provision of accessible and affordable healthcare services. Awareness campaigns for the health education of pregnant women should focus on raising awareness to support better pregnancy outcomes for poor women living in communities with higher education levels. The risk of stillbirth can be reduced by offering free diagnostics for early detection of birth complications in low-resource settings and referring these cases to knowledgeable gynecologists for safe delivery.

Exploring first-time mothers' experiences and knowledge about behavioural risk factors for stillbirth

BACKGROUND

Modifiable factors such as substance use, lack of attendance at antenatal care, overweight or obesity and sleeping position are associated with a higher risk of stillbirth. This qualitative study aimed to explore women's experiences of modifiable factors during pregnancy and their awareness of stillbirth.

METHODS

Purposive sampling was implemented by hospital staff in a large tertiary maternity hospital in Ireland between November 2020 and March 2021. Women were approached during their stay in the hospital and were invited to participate in a semistructured interview 3-5 months later. Eligible women were primiparous, >18 years of age and had an uncomplicated pregnancy and delivery. Eighteen women who consented to be followed up were interviewed at 3-5 months postpartum. Thematic analysis was used to analyse the data.

RESULTS

Four themes were identified: attitudes towards behaviour change, awareness regarding stillbirth and risk factors, the silence around stillbirth and risks, and attitudes towards receiving information about stillbirth. Women spoke about behaviour change in terms of outcomes, and most changes (e.g., ceasing alcohol consumption) were perceived as easy to manage. Awareness of stillbirth was limited among the women interviewed, and the association between risk behaviours and stillbirth was not known by any woman. Results suggest that there is a silence around stillbirth, including in antenatal care, which hinders information provision. However, most women highlighted the value of receiving information and extra education about modifiable risk factors and stillbirth.

CONCLUSION

There is a general lack of understanding of the link between behavioural risk factors and potential pregnancy outcomes such as stillbirth. Providing further information to women about stillbirth and providing additional support with behaviour change might contribute to enhancing preventive efforts.

PATIENT OR PUBLIC CONTRIBUTION

Patients were involved in this study by providing their experiences of antenatal care which were used as primary data.

Socioeconomic inequality and stillbirth rate disparities among native and foreign mothers: evidence from Greece

We study, for the first time, stillbirth differentials among native and migrant populations in Greece using national vital registration microdata for the period of 2010–2014. We employ conventional demographic measures and propose a standardization procedure to delineate the effect of selected distributions of livebirths on the observed stillbirth rates. The stillbirth rate among immigrant mothers is 40% higher than among natives, an excess which persists throughout gestational intervals and age groups. Our findings also show a clear gradient of stillbirth rates by maternal education, favoring more educated women, and this finding applies to both native and immigrant mothers. Our standardization methodology shows that the distribution of births by maternal educational level and age play a role; this finding implies that elevated immigrant stillbirth rates may be attributed to a certain extent to the specific characteristics of this group, since immigrant women have, on average, a younger age structure and lower educational attainment.

Hispanic Ethnicity, Nativity and the Risk of Stillbirth

The objective of this study was to examine stillbirth risk by nativity and Hispanic ethnicity. We analyzed births and fetal deaths among women of Hispanic origin within gestational ages of 20-42 weeks from the 2014-2019 Birth and Fetal Death. Foreign-born Hispanic mothers were 8% less likely (HR 0.92, 95% CI 0.90-0.95) to experience stillbirth than their counterparts. Stratified by ethnicity, foreign-born Mexican and Central/South American women had a lower risk of stillbirth (HR 0.85, 95% CI 0.81-0.88 and HR 0.68, 95% CI 0.63-0.75, respectively) while foreign-born Puerto Rican women were more likely to experience stillbirth (HR 1.37, 95% CI 1.24-1.51) than their native-born counterparts. While overall foreign-born Hispanic mothers were less likely to experience stillbirth than native-born Hispanic mothers, this differed depending on ethnicity. Counseling regarding risk of stillbirth among Hispanic women should take into consideration nativity and country of origin as influential factors.

Association between obstetric and medical risk factors and stillbirths in a low-income urban setting

OBJECTIVE

To evaluate the association between obstetric and medical risk factors and stillbirths in a Kenyan set-up.

METHODS

A case-control study was conducted in four hospitals between August 2018 and April 2019. Two hundred and fourteen women with stillbirths and 428 with live births at more than >28 weeks of gestation were enrolled. Data collection was via interviews and abstraction from medical records. Outcome variables were stillbirth and live birth; exposure variables were sociodemographic characteristics, and medical and obstetric factors. The two-sample t test and χ2 test were used to compare continuous and categorical variables respectively. The association between the exposure and outcome variable was done using logistic regression. A P value less than 0.05 was considered statistically significant.

RESULTS

Stillbirth was associated with pre-eclampsia without severe features (odds ratio [OR] 9.1, 95% confidence interval [CI] 2.6-32.5), pre-eclampsia with severe features (OR 7.4, 95% CI 2.4-22.8); eclampsia (OR 9.2, 95% CI 2.6-32.5), placenta previa (OR 8.6 95% CI 2.8-25.9), placental abruption (OR 6.9 95% CI 2.2-21.3), preterm delivery(OR 9.5, 95% CI 5.7-16), and gestational diabetes mellitus, (OR 11.5, 95% CI 2.5-52.6). Stillbirth was not associated with multiparity, anemia, and HIV.

CONCLUSION

Proper antepartum care and surveillance to identify and manage medical and obstetric conditions with the potential to cause stillbirth are recommended.

Prevalence of stillbirth and its associated factors in East Africa: generalized linear mixed modeling

BACKGROUND

Stillbirth is the most frequently reported adverse pregnancy outcome worldwide, which imposes significant psychological and economic consequences to mothers and affected families. East African countries account for one-third of the 2.6 million stillbirths globally. Though stillbirth is a common public health problem in East African countries, there is limited evidence on the pooled prevalence and associated factors of stillbirth in East Africa. Therefore, this study aimed to investigate the prevalence of stillbirth and its associated factors in East Africa.

METHODS

This study was based on the most recent Demographic and Health Surveys (DHSs) of 12 East African countries. A total weighted sample of 138,800 reproductive-age women who gave birth during the study period were included in this study. The prevalence of stillbirth with the 95% Confidence Interval (CI) was reported using a forest plot. A mixed-effect binary logistic regression analysis was done to identify significantly associated factors of stillbirth. Since the DHS data has hierarchical nature, the presence of clustering effect was assessed using the Likelihood Ratio (LR) test, and Intra-cluster Correlation Coefficient (ICC), and deviance were used for model comparison. Variables with a p-value of less than 0.2 in the bi-variable analysis were considered for the multivariable analysis. In the multivariable mixed-effect binary logistic regression analysis, the Adjusted Odds Ratio (AOR) with 95% CI were reported to declare the strength and significance of the association.

RESULTS

The prevalence of stillbirth in East Africa was 0.86% (95% CI: 0.82, 0.91) ranged from 0.39% in Kenya to 2.28% in Burundi. In the mixed-effect analysis; country, women aged 25-34 years (AOR = 1.27, 95% CI: 1.11, 1.45), women aged ≥ 35 years (AOR = 1.19, 95% CI: 1.01, 1.44), poor household wealth (AOR = 1.07, 95% CI: 1.02, 1.23), women who didn't have media exposure (AOR = 1.11, 95% CI: 1.01, 1.25), divorced/widowed/separated marital status (AOR = 2.99, 95% CI: 2.04, 4.39), caesarean delivery (AOR = 1.81, 95% CI: 1.52, 2.15), preceding birth interval < 24 months (AOR = 1.15, 95% CI: 1.06, 1.24), women attained secondary education or above (AOR = 0.68, 95% CI: 0.56, 0.81) and preceding birth interval ≥ 49 months (AOR = 1.45, 95% CI: 1.28, 1.65) were significantly associated with stillbirth.

CONCLUSIONS

Stillbirth remains a major public health problem in East Africa, which varied significantly across countries. These findings highlight the weak health care system of East African countries. Preceding birth interval, county, maternal education media exposure, household wealth status, marital status, and mode of delivery were significantly associated with stillbirth. Therefore, public health programs enhancing maternal education, media access, and optimizing birth spacing should be designed to reduce the incidence of stillbirth.

Proposing a machine-learning based method to predict stillbirth before and during delivery and ranking the features: nationwide retrospective cross-sectional study

Background

Stillbirth is defined as fetal loss in pregnancy beyond 28 weeks by WHO. In this study, a machine-learning based method is proposed to predict stillbirth from livebirth and discriminate stillbirth before and during delivery and rank the features.

Method

A two-step stack ensemble classifier is proposed for classifying the instances into stillbirth and livebirth at the first step and then, classifying stillbirth before delivery from stillbirth during the labor at the second step. The proposed SE has two consecutive layers including the same classifiers. The base classifiers in each layer are decision tree, Gradient boosting classifier, logistics regression, random forest and support vector machines which are trained independently and aggregated based on Vote boosting method. Moreover, a new feature ranking method is proposed in this study based on mean decrease accuracy, Gini Index and model coefficients to find high-ranked features.

Results

IMAN registry dataset is used in this study considering all births at or beyond 28th gestational week from 2016/04/01 to 2017/01/01 including 1,415,623 live birth and 5502 stillbirth cases. A combination of maternal demographic features, clinical history, fetal properties, delivery descriptors, environmental features, healthcare service provider descriptors and socio-demographic features are considered. The experimental results show that our proposed SE outperforms the compared classifiers with the average accuracy of 90%, sensitivity of 91%, specificity of 88%. The discrimination of the proposed SE is assessed and the average AUC of ±95%, CI of 90.51% ±1.08 and 90% ±1.12 is obtained on training dataset for model development and test dataset for external validation, respectively. The proposed SE is calibrated using isotopic nonparametric calibration method with the score of 0.07. The process is repeated 10,000 times and AUC of SE classifiers using random different training datasets as null distribution. The obtained p-value to assess the specificity of the proposed SE is 0.0126 which shows the significance of the proposed SE.

Conclusions

Gestational age and fetal height are two most important features for discriminating livebirth from stillbirth. Moreover, hospital, province, delivery main cause, perinatal abnormality, miscarriage number and maternal age are the most important features for classifying stillbirth before and during delivery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03658-z.

Factors Associated With Stillbirth Among Pregnant Women in Nepal

OBJECTIVES

Stillbirth is a common adverse pregnancy outcome that represents a distressing and traumatic event for women and their partners. The aim of this study was to identify factors associated with stillbirth in ever-pregnant women in Nepal.

METHODS

This study utilized the individual women's dataset from the Nepal Demographic and Health Survey, conducted in 2016. The dependent variable of interest was whether women had at least 1 stillbirth during their lifetime. The associations between independent variables and the dependent variable of the study were analyzed using a multiple logistic regression model.

RESULTS

Among 8918 ever-pregnant women aged 15-49 years, 488 had experienced at least 1 stillbirth during their lifetime, representing 5.5% of the total. After adjusting each factor for the confounding effects of other factors, maternal age, maternal education, place of residence, and sub-region remained significantly associated with having experienced stillbirth.

CONCLUSIONS

Stillbirth continues to be a major problem among women, especially those with higher maternal age, those who are illiterate, and residents of certain geographical regions. To minimize stillbirth in Nepal, plans and policies should be focused on women with low education levels and residents of rural areas, especially in the western mountain and far-western hill regions.

Risk factors of stillbirth in rural China: A national cohort study

People living in rural China are more frequently exposed to some specific risk factors which made stillbirth rate higher than urban areas. National Free Preconception Health Examination Project was launched to investigate these risk factors and collected a representative sample of 248501 participants from 31 provinces in China from 2010 to 2013. Parental risk factors were ascertained twice before and during pregnancy respectively by questionnaires. Stillbirth or live birth were recorded by trained physicians. In the analysis, nested case-control study was conducted, and propensity score matching method was used to adjust the confounding. Multi-level logistic regression was used to fit for multi-level sampling. The overall stillbirth rate was 0.35% in rural China, it was higher in North (0.42%) and West (0.64%) areas. Maternal exposure to pesticide (OR (95%CI 1.06, 3.39)), hypertension (OR = 1.58 (95%CI 1.07, 2.34)), lack of appetite for vegetables (OR = 1.99 (95%CI 1.00, 3.93)), stress (compared with no pressure, OR of a little pressure was 1.34(95% CI 1.02, 1.76)); paternal exposure to smoking (OR = 1.22 (95% CI 1.02, 1.46)), organic solvents (OR = 1.64 (95% CI 1.01, 2.69)) were found independent risk factors of stillbirth. Folacin intake 3 months before pregnancy (OR = 0.72 (95%) CI 0.59, 0.89), folacin intake 1-2 months before pregnancy (OR = 0.71 (95% CI 0.55, 0.92)), folacin intake after pregnancy (OR = 0.81 (95% CI 0.65, 1.02) for) were protect factors of stillbirth. Maternal pesticide exposure, lack of vegetables, stress, paternal smoking and exposure to organic solvents were risk factors of stillbirth. Folic acid intake was protective factor of stillbirth, no matter when the intake began.

Maternal education and newborn thyroid-stimulating hormone level in a congenital hypothyroidism screening program

Objective: To examine the relationship between neonatal thyroid function and the formal education of mothers.Study design: Participants came from a population-based congenital hypothyroidism (CH) screening program in Tianjin, China.Methods: Of 66,390 registered births in 2015, 60,568 mothers and newborns had complete data. Mothers were categorized into one of four categories based on their educational attainment: (a) midschool or less; (b) high school or equivalent; (c) university; or (d) post graduate. Newborn thyroid-stimulating hormone (TSH) level was measured on day 3-7. Two neonatal groups were created using cutoffs of TSH > 10 μIU/ml and TSH > 20 μIU/ml. Odds ratios (OR) for CH risk by maternal education were estimated from logistic regression models after adjusting for potential confounders.Results: For TSH > 10 μIU/ml, the screen positive incidence rate for CH was 1:201 or 4.98 per 1000 births; for TSH > 20 μIU/ml, the incidence rate was 1:2222 or 0.45 per 1000 births. Screen positive incidence rates decreased with increasing maternal education level. Compared to mothers with a postgraduate education, the ORs (95% CI) for midschool or less, high school or equivalent, and university were 2.09 (1.08, 4.04), 1.45 (0.73, 2.90), and 1.61 (0.85, 3.06) using a cutoff of TSH > 10 μIU/ml. At the higher cutoff of TSH > 20 μIU/ml ORs (95% CI) for midschool or less and high school or equivalent were 3.05 (1.20,7.74) and 3.34 (1.24, 8.97), when compared to a composite reference category of university and postgraduate level education.Conclusion: Maternal education is inversely related to neonatal thyroid function though the mechanism remains unexplained.

Parental age and stillbirth: a population-based cohort of nearly 10 million California deliveries from 1991 to 2011

PURPOSE

Parental age at delivery in the United States has been rising. Advanced maternal and paternal ages have been associated with adverse pregnancy outcomes including stillbirth. However, these relationships come from studies that often do not present results for both mother and father concurrently. The purpose of this study was to estimate the risk of stillbirth for maternal and paternal age in the same cohort of deliveries.

METHODS

This is a population-based cohort study of all live birth and stillbirth deliveries in California from 1991 to 2011. The individual associations between maternal and paternal ages and stillbirth were estimated with hazard ratios from Cox proportional hazard models. Age was modeled continuously with restricted cubic splines to account for nonlinear relationships. Mean parental age was used as the referent group.

RESULTS

J-shaped associations between maternal and paternal ages were observed in crude models where older mothers and fathers had the highest hazard ratios for stillbirth. In maternal models, after adjusting for maternal and paternal covariates, young maternal age no longer showed increased hazard ratio for stillbirth, whereas the association with older mothers remained. In adjusted paternal models, the relationship between young paternal age and stillbirth was unchanged while the hazard ratio for older fathers was slightly smaller.

CONCLUSIONS

After adjusting for both parents' age, education, race/ethnicity, along with parity, older mothers and fathers were independently associated with elevated hazard ratios for stillbirth.

Socio-economic predictors of stillbirths in Nepal (2001-2011)

INTRODUCTION

Stillbirth has a long-lasting impact on parents and families. This study examined socio-economic predictors associated with stillbirth in Nepal for the year 2001, 2006 and 2011.

METHODS

The Nepalese Demographic and Health Survey (NDHS) data for the period (2001-2011) were pooled to estimate socio-economic predictors associated with stillbirths in Nepal using binomial logistic regression while taking clustering and sampling weights into account.

RESULTS

A total of 18,386 pregnancies of at least 28 weeks gestation were identified. Of these pregnancies, 335 stillbirths were reported. Stillbirth increased significantly among women that lived in the hills ecological zones (aRR 1.38, 95% CI 1.02, 1.87) or in the mountains ecological zones (aRR 1.71, 95% CI 1.10, 2.66). Women with no schooling (aRR 1.72, 95% CI 1.10, 2.69), women with primary education (aRR 1.81, 95% CI 1.11, 2.97); open defecation (aRR 1.48, 95% CI 1.00, 2.18), and those whose major occupation was agriculture (aRR 1.80, 95% CI 1.16, 2.78) are more likely to report higher stillbirth.

CONCLUSIONS

Low levels of education, ecological zones and open defecation were found to be strong predictors of stillbirth. Access to antenatal care services and skilled birth attendants for women in the mountainous and hilly ecological zones of Nepal is needed to further reduce stillbirth and improved services should also focus on women with low levels of education.

Do biomass fuel use and consumption of unsafe water mediate educational inequalities in stillbirth risk? An analysis of the 2007 Ghana Maternal Health Survey

BACKGROUND

Numerous studies have explored the association between educational inequalities and stillbirth but most have failed to elaborate how low educational attainment leads to an increased risk of stillbirth. We hypothesised that use of biomass fuels and consumption of unsafe water related to low educational attainment could explain the stillbirth burden in Ghana attributable to socioeconomic disadvantage.

METHODS

Data from the 2007 Ghana Maternal Health Survey, a nationally representative population-based survey were analysed for this study. Of the10 370 women aged 15-49 years interviewed via structured questionnaires for the survey, 7183 primiparous and multiparous women qualified for inclusion in the present study.

RESULTS

In a logistic regression analysis that adjusted for age, area of residence, marital status and ethnicity of women, lower maternal primary education was associated with a 62% (OR=1.62; 95% CI 1.04 to 2.52) increased lifetime risk of stillbirth. Biomass fuel use and consumption of unsafe water mediated 18% and 8% of the observed effects, respectively. Jointly these two exposures explained 24% of the observed effects. The generalised additive modelling revealed a very flat inverted spoon-shaped smoothed curve which peaked at low levels of schooling (2-3 years) and confirms the findings from the logistic regression analysis.

CONCLUSIONS

Our results show that biomass fuel use and unsafe water consumption could be important pathways through which low maternal educational attainment leads to stillbirths in Ghana and similar developing countries. Addressing educational inequalities in developing countries is thus essential for ensuring household choices that curtail environmental exposures and help improve pregnancy outcomes.

Socioeconomic inequalities in stillbirth rates in Europe: measuring the gap using routine data from the Euro-Peristat Project

BACKGROUND

Previous studies have shown that socioeconomic position is inversely associated with stillbirth risk, but the impact on national rates in Europe is not known. We aimed to assess the magnitude of social inequalities in stillbirth rates in European countries using indicators generated from routine monitoring systems.

METHODS

Aggregated data on the number of stillbirths and live births for the year 2010 were collected for three socioeconomic indicators (mothers' educational level, mothers' and fathers' occupational group) from 29 European countries participating in the Euro-Peristat project. Educational categories were coded using the International Standard Classification of Education (ISCED) and analysed as: primary/lower secondary, upper secondary and postsecondary. Parents' occupations were grouped using International Standard Classification of Occupations (ISCO-08) major groups and then coded into 4 categories: No occupation or student, Skilled/ unskilled workers, Technicians/clerical/service occupations and Managers/professionals. We calculated risk ratios (RR) for stillbirth by each occupational group as well as the percentage population attributable risks using the most advantaged category as the reference (post-secondary education and professional/managerial occupations).

RESULTS

Data on stillbirth rates by mothers' education were available in 19 countries and by mothers' and fathers' occupations in 13 countries. In countries with these data, the median RR of stillbirth for women with primary and lower secondary education compared to women with postsecondary education was 1.9 (interquartile range (IQR): 1.5 to 2.4) and 1.4 (IQR: 1.2 to 1.6), respectively. For mothers' occupations, the median RR comparing outcomes among manual workers with managers and professionals was 1.6 (IQR: 1.0-2.1) whereas for fathers' occupations, the median RR was 1.4 (IQR: 1.2-1.8). When applied to the entire set of countries with data about mothers' education, 1606 out of 6337 stillbirths (25 %) would not have occurred if stillbirth rates for all women were the same as for women with post-secondary education in their country.

CONCLUSIONS

Data on stillbirths and socioeconomic status from routine systems showed widespread and consistent socioeconomic inequalities in stillbirth rates in Europe. Further research is needed to better understand differences between countries in the magnitude of the socioeconomic gradient.

Risk of fetal death with preeclampsia

OBJECTIVE

To estimate gestational age-specific risks of fetal death in pregnancies complicated by preeclampsia.

METHODS

Population-based cohort study comprising all singleton births (N=554,333) without preexisting chronic hypertension recorded in the Norwegian Medical Birth Registry from 1999 to 2008. Additional data come from a subset of preeclamptic pregnancies enrolled in the Norwegian Mother and Child Cohort Study with available medical records (n=3,037). The risk of fetal death, expressed per 1,000 fetuses exposed to preeclampsia, was calculated using a life table approach.

RESULTS

Preeclampsia was recorded in 3.8% (n=21,020) of all pregnancies. Risk of stillbirth was 3.6 per 1,000 overall and 5.2 per 1,000 among pregnancies with preeclampsia (relative risk 1.45, 95% confidence interval [CI] 1.20-1.76). However, relative risk of stillbirth was markedly elevated with preeclampsia in early pregnancy. At 26 weeks of gestation, there were 11.6 stillbirths per 1,000 pregnancies with preeclampsia compared with 0.1 stillbirths per 1,000 pregnancies without (relative risk 86, 95% CI 46-142). Fetal risk with preeclampsia declined as pregnancy advanced, but at 34 weeks of gestation remained more than sevenfold higher than pregnancies without preeclampsia.

CONCLUSION

For clinical purposes, the fetal risk of death associated with preeclampsia begins when preeclampsia becomes clinically apparent. Using a method that takes into account the clinical diagnosis of preeclampsia and the population of fetuses at risk, we find a remarkably high relative risk of fetal death among pregnancies diagnosed with preeclampsia in the preterm period.

LEVEL OF EVIDENCE

II.

Fetuses-at-risk, to avoid paradoxical associations at early gestational ages: extension to preterm infant mortality

BACKGROUND

Fetuses-at-risk denominators are commonly used in research on preterm stillbirth, but applications to postnatal outcomes such as preterm infant mortality are controversial. We evaluated whether biased associations between maternal risk factors and preterm infant mortality caused by stratification by preterm birth could be avoided using fetuses-at-risk risk ratios.

METHODS

Data included 3 277 570 births drawn from the linked live birth-death file for Canada from 1990 through 2005. We used maternal age as the risk factor, and estimated the association with stillbirth, early neonatal, late neonatal and postneonatal mortality by gestational interval (22-24, 25-27, 28-31, 32-36, ≥37 weeks). Models were run using (i) log-binomial regression stratified by preterm gestational age, and (ii) unstratified log-binomial regression using fetuses-at-risk denominators.

RESULTS

Extremes of maternal age were associated with higher mortality among term births. Among preterm births, the stratified model suggested a protective, null or attenuated association of extremes of maternal age with stillbirth, early, late and post neonatal mortality. The unstratified fetuses-at-risk model, however, resulted in the expected higher risk of mortality at extremes of maternal age for all outcomes.

CONCLUSIONS

Fetuses-at-risk regression can avoid paradoxical associations between maternal exposures and mortality of infants born early in gestation, caused by preterm birth stratification bias. The fetuses-at-risk approach can be extended through the first year of life, or potentially beyond, depending on the outcome and presence of unmeasured confounders associated with preterm birth.

Stillbirth rates among Haitians in Canada

BACKGROUND

Data on cultural groups at risk of stillbirth in high-income countries are scarce. We sought to determine disparities in stillbirth by gestational age for Haitian vs. non-Haitian Canadians.

METHODS

We used data on 10,287 stillbirths and 2,482,364 livebirths from 1981-2010 in the province of Quebec, Canada. Stillbirth rates for Haitians were compared with non-Haitians using fetuses at risk denominators, and Cox proportional hazards regression models with gestational age as the time scale.

RESULTS

Stillbirth rates were much higher for Haitians than non-Haitians during the study period (7.2 vs. 3.9 per 1000 total births). Disparities between Haitians and non-Haitians were largest at 32-36 weeks of gestation [hazard ratio 2.22, 95% confidence interval 1.61, 3.07].

CONCLUSIONS

Stillbirth rates in Haitian Canadians giving birth in Quebec are exceptionally high. Disparities were greatest during the late preterm period.

Gestational age-dependent risk factors for preterm birth: associations with maternal education and age early in gestation

OBJECTIVES

Preterm birth (PTB) before 37 weeks can occur over a wide range of gestational ages, but few studies have assessed if associations between risk factors and PTB vary over the duration of gestation. We sought to evaluate if associations between two major risk factors (maternal education and age) and PTB depend on gestational age at delivery.

STUDY DESIGN

We estimated hazard ratios of PTB for education and age in a time-to-event analysis using a retrospective cohort of 223,756 live singleton births from the province of Québec, Canada for the years 2001-2005. Differences in hazards of maternal education and age with PTB were assessed over gestational age in a Cox proportional hazards model using linear and nonlinear time interaction terms, adjusting for maternal characteristics.

RESULTS

Associations of PTB with lower (vs. higher) education and older (vs. younger) age strengthened progressively at earlier gestational ages, such that the risk of PTB for maternal education and age was not constant over the course of gestation.

CONCLUSIONS

Associations of PTB with risk factors such as maternal low education and older age may be stronger early in gestation. Models that capture the time-dependent nature of PTB may be useful when the goal is to assess associations at low gestational ages, and to avoid masked or biased associations early in gestation.

Incidence of preeclampsia: risk factors and outcomes associated with early- versus late-onset disease

OBJECTIVE

The population-based incidence of early-onset (<34 weeks) and late-onset preeclampsia (≥34 weeks) has not been adequately studied. We examined the gestational age-specific incidence of preeclampsia onset and identified the associated risk factors and birth outcomes.

STUDY DESIGN

All singleton deliveries in Washington State, 2003-2008 (n = 456,668), were included, and preeclampsia onset was determined from hospital records linked to birth certificates. Cox and logistic regression models were used to obtain adjusted hazard ratios and odds ratios (AORs) for risk factors and birth outcomes, respectively.

RESULTS

The overall preeclampsia rate was 3.1% and the incidence increased sharply with gestation; early- and late-onset preeclampsia rates were 0.38% and 2.72%, respectively. Among women with early-onset preeclampsia, 12% delivered at a gestation of 34 weeks or longer. Risk/protective factors common to both diseases included older maternal age, Hispanic and Native-American race, smoking, unmarried status, and male fetus. African-American race, chronic hypertension, and congenital anomalies were more strongly associated with early-onset preeclampsia, whereas younger maternal age, nulliparity, and diabetes mellitus were more strongly associated with late-onset disease. Early- but not late-onset preeclampsia conferred a high risk of fetal death (AOR, 5.8; 95% confidence interval [CI], 4.0-8.3 vs AOR, 1.3; 95% CI, 0.8-2.0, respectively). The AOR for perinatal death/severe neonatal morbidity was 16.4 (95% CI, 14.5-18.6) in early-onset and 2.0 (95% CI, 1.8-2.3) in late-onset preeclampsia.

CONCLUSION

Early- and late-onset preeclampsia shares some etiological features, differ with regard to several risk factors, and lead to different outcomes. The 2 preeclampsia types should be treated as distinct entities from an etiological and prognostic standpoint.

Risk factors and trends in the rate of stillbirth in Hungary between 1971 and 2010

OBJECTIVE

Possible risk factors and trends in the rate of stillbirth in Hungary between 1971 and 2010.

METHODS

Annual data of fetal birth weight, fetal gender, maternal age and marital status of the mother categories were available for both live and stillborn cases and were analyzed using negative binomial regression. A p value less than 0.05 was considered significant.

RESULTS

Male gender significantly increased risk of stillbirth (relative risk (RR):1.08; p < 0.001). The risk of stillbirth was also significantly associated with the maternal age (RR: 2.01 in the group older than 35 years, relative to younger mothers; p < 0.001), and the marital status (RR: 1.24 among the babies of an extramarital partnership; p < 0.001), this holding true for both fetal genders. However, a low birth weight ( < 2500 g) increased the risk of stillbirth more than 18-fold (RR: 18.47; p < 0.001) and there was a markedly higher risk of low birth weight in boys than in girls. Further, a strong negative correlation (r = -0.88) was detected between the real income per person of the overall population and the rate of stillbirth.

CONCLUSIONS

These findings support the known risk factors of stillbirth and gender-specific analyses given an estimation of the risk of stillbirth in both boys and girls.

Does advanced maternal age confer a survival advantage to infants born at early gestation?

BACKGROUND

Recent studies have shown that older mothers who deliver at preterm gestation have lower neonatal mortality rates compared with younger mothers who deliver at preterm gestation. We examined the effect of maternal age on gestational age-specific perinatal mortality.

METHODS

We compared fetal, neonatal and perinatal mortality rates among singleton births in the United States, 2003-2005, to mothers aged ≥35 versus 20-29 years. The analysis was stratified by gestational age and perinatal mortality rates were contrasted by maternal age at earlier (22-33 weeks) and later gestation (≥34 weeks). Gestational age-specific perinatal mortality rates were calculated using the traditional perinatal formulation (deaths among births at any gestation divided by total births at that gestation) and also the fetuses-at-risk model (deaths among births at any gestation divided by fetuses-at-risk of death at that gestation).Logistic regression was used to estimate adjusted odds ratios (AOR) for perinatal death.

RESULTS

Under the traditional approach, fetal death rates at 22-33 weeks were non-significantly lower among older mothers (AOR 0.97, 95% confidence interval [CI] 0.91-1.03), while rates were significantly higher among older mothers at ≥34 weeks (AOR 1.66, 95% CI 1.56-1.76). Neonatal death rates were significantly lower among older compared with younger mothers at 22-33 weeks (AOR=0.93, 95% CI 0.88-0.98) but higher at ≥34 weeks (AOR 1.26, 95% CI 1.21-1.31). Under the fetuses-at-risk model, both rates were higher among older vs younger mothers at early gestation (AOR for fetal and neonatal mortality 1.35, 95% CI 1.27-1.43 and 1.31, 95% CI 1.24-1.38, respectively) and late gestation (AOR for fetal and neonatal mortality 1.66, 95% CI 1.56-1.76) and 1.21, 95% CI 1.14-1.29, respectively).

CONCLUSIONS

Although the traditional prognostic perspective on the risk of perinatal death among older versus younger mothers varies by gestational age at birth, the causal fetuses-at-risk model reveals a consistently elevated risk of perinatal death at all gestational ages among older mothers.

Rates of stillbirth by gestational age and cause in Inuit and First Nations populations in Quebec

BACKGROUND

Inuit and First Nations populations have higher rates of stillbirth than non-Aboriginal populations in Canada do, but little is known about the timing and cause of stillbirth in Aboriginal populations. We compared gestational age- and cause-specific stillbirth rates in Inuit and First Nations populations with the rates in the non-Aboriginal population in Quebec.

METHODS

Data included singleton stillbirths and live births at 24 or more gestational weeks among Quebec residents from 1981 to 2009. We calculated odds ratios (ORs), rate differences and 95% confidence intervals (CIs) for the retrospective cohort of Inuit and First Nations births relative to non-Aboriginal births using fetuses at risk (i.e., ongoing pregnancies) as denominators and adjusting for maternal characteristics. The main outcomes were stillbirth by gestational age (24-27, 28-36, ≥ 37 wk) and cause of death.

RESULTS

Rates of stillbirth per 1000 births were greater among Inuit (6.8) and First Nations (5.7) than among non-Aboriginal (3.6) residents. Relative to the non-Aboriginal population, the risk of stillbirth was greater at term (≥ 37 wk) than before term for both Inuit (OR 3.1, 95% CI 1.9 to 4.8) and First Nations (OR 2.6, 95% CI 2.1 to 3.3) populations. Causes most strongly associated with stillbirth were poor fetal growth, placental disorders and congenital anomalies among the Inuit, and hypertension and diabetes among the First Nations residents.

INTERPRETATION

Stillbirth rates in Aboriginal populations were particularly high at term gestation. Poor fetal growth, placental disorders and congenital anomalies were important causes of stillbirth among the Inuit, and diabetic and hypertensive complications were important causes in the First Nations population. Prevention may require improvements in pregnancy and obstetric care.

Educational inequality in stillbirth: temporal trends in Québec from 1981 to 2009

OBJECTIVE

Educational inequality in stillbirth has been documented in high-income countries and the province of Québec, Canada, but temporal trends are poorly understood. Our objective was to determine time trends in inequality related to maternal education for all-cause and cause-specific stillbirth over the past three decades in Québec.

METHODS

We included 2,397,971 live births and 9,983 stillbirths from 1981 through 2009 using Québec vital statistics. For each decade, we computed measures of inequality capturing relative (relative index of inequality, RII) and absolute (slope index of inequality, SII) differences between the least- and most-educated mothers for all-cause and cause-specific stillbirth, adjusting for maternal characteristics.

RESULTS

Stillbirth rates decreased over time for all education levels. Absolute educational inequality (SII 2.5 per 1000 births, 95% CI 2.1-2.8; all periods combined) was stable over time, whereas relative inequality increased (RII(1981-1989) 1.8 vs. RII(2000-2009) 2.3). Absolute inequality decreased for stillbirths caused by placental abruption (SII(1981-1989) 0.6 vs. SII(2000-2009) 0.3), but increased for unspecified causes (SII(1981-1989) 0.2 vs. SII(2000-2009) 0.7).

CONCLUSIONS

Absolute educational inequality in stillbirth persisted and relative inequality increased over the past three decades, despite an overall decrease in stillbirth rates. The decrease in absolute inequality for placental abruption was countered by an increase for unspecified causes. A better understanding of the underlying components of unspecified causes is needed to further address educational inequality in stillbirth.

Francophone and Anglophone perinatal health: temporal and regional inequalities in a Canadian setting, 1981-2008

OBJECTIVES

We evaluated temporal and regional inequalities in adverse birth outcomes between Anglophones and Francophones of a Canadian province.

METHODS

Odds ratios and rate differences in preterm birth (PTB, <37 gestational weeks) and small-for-gestational-age (SGA) birth were computed for Anglophones relative to Francophones for singleton live births in Québec from 1981 to 2008 (N = 2,292,237), adjusting for maternal characteristics. Trends over time and residential region were evaluated.

RESULTS

Rates of PTB and SGA birth overall were lower for Anglophones relative to Francophones, but temporal and regional trends varied by outcome. Although PTB rates increased over time, inequalities between Francophones and Anglophones were relatively stable. In contrast, inequalities in SGA birth narrowed over time as Francophone rates declined more than Anglophones. Inequalities in SGA birth favored Anglophones overall, but the gap gradually reversed in Montréal (the largest metropolitan center) to currently favor Francophones.

CONCLUSIONS

PTB and SGA birth rates favored Anglophones over Francophones. The linguistic gap was generally stable over time for PTB, but narrowed or reversed for SGA birth. Language may be used to capture inequalities in perinatal health in countries where different linguistic groups predominate.

Educational inequalities in preterm and term small-for-gestational-age birth over time

PURPOSE

Time trends in educational inequalities in small-for-gestational-age (SGA) birth are important to evaluate for policy, especially at preterm gestational ages when morbidity and mortality are typically greater. We evaluated educational inequalities in preterm and term SGA birth over time, accounting for potential bias at preterm gestational ages.

METHODS

Data included 2,204,056 singleton live births from 25 to 43 gestational weeks, 1981 to 2007. We estimated prevalence ratios (PR) and percent prevalence differences (PPD) of preterm and term SGA birth for a continuous education score, accounting for maternal characteristics. Sensitivity analyses included correction for misclassification of preterm SGA status, and use of fetuses-at-risk denominators in regression models.

RESULTS

Although prevalence of SGA birth decreased over time, relative educational inequalities (PRs) persisted for preterm and term cases. PPDs decreased slightly, but more for term than preterm SGA birth. Sensitivity analyses indicated that PRs for education were stronger for preterm than term SGA birth. PPDs were larger for term SGA birth in the first period, but greater for preterm SGA birth in the last period.

CONCLUSIONS

Relative educational inequalities in SGA birth persisted over time. The difference in prevalence between the least and most educated mothers is currently greater for preterm than for term SGA birth.