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International variations in the gestational age distribution of births: an ecological study in 34 high-income countries.

ABSTRACT: Background:Few studies have investigated international variations in the gestational age (GA) distribution of births. While preterm births (22-36 weeks GA) and early term births (37-38 weeks) are at greater risk of adverse health outcomes compared to full term births (39-40 weeks), it is not known if countries with high preterm birth rates also have high early term birth rates. We examined rate associations between preterm and early term births and mean term GA by mode of delivery onset. Methods:We used routine aggregate data on the GA distribution of singleton live births from up to 34 high-income countries/regions in 1996, 2000, 2004, 2008 and 2010 to study preterm and early term births overall and by spontaneous or indicated onset. Pearson correlation coefficients were adjusted for clustering in time trend analyses. Results:Preterm and early term births ranged from 4.1% to 8.2% (median 5.5%) and 15.6% to 30.8% (median 22.2%) of live births in 2010, respectively. Countries with higher preterm birth rates in 2004-2010 had higher early term birth rates (r > 0.50, P < 0.01) and changes over time were strongly correlated overall (adjusted-r = 0.55, P < 0.01) and by mode of onset. Conclusion:Positive associations between preterm and early term birth rates suggest that common risk factors could underpin shifts in the GA distribution. Targeting modifiable population risk factors for delivery before 39 weeks GA may provide a useful preterm birth prevention paradigm.

SUBMITTER: Delnord M

PROVIDER: S-EPMC6454414 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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International variations in the gestational age distribution of births: an ecological study in 34 high-income countries.

Delnord Marie M Mortensen Laust L Hindori-Mohangoo Ashna D AD Blondel Béatrice B Gissler Mika M Kramer Michael R MR Richards Jennifer L JL Deb-Rinker Paromita P Rouleau Jocelyn J Morisaki Naho N Nassar Natasha N Bolumar Francisco F Berrut Sylvie S Nybo Andersen Anne-Marie AM Kramer Michael S MS Zeitlin Jennifer J

European journal of public health 20180401 2

<h4>Background</h4>Few studies have investigated international variations in the gestational age (GA) distribution of births. While preterm births (22-36 weeks GA) and early term births (37-38 weeks) are at greater risk of adverse health outcomes compared to full term births (39-40 weeks), it is not known if countries with high preterm birth rates also have high early term birth rates. We examined rate associations between preterm and early term births and mean term GA by mode of delivery onset. ...[more]

PMID: 29020399

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Project description:BackgroundFetal and neonatal mortality rates are essential indicators of population health, but variations in recording of births and deaths at the limits of viability compromises international comparisons. The World Health Organization recommends comparing rates after exclusion of births with a birth weight less than 1000 grams, but many analyses of perinatal outcomes are based on gestational age. We compared the effects of using a 1000-gram birth weight or a 28-week gestational age threshold on reported rates of fetal and neonatal mortality in Europe.MethodsAggregated data from 2004 on births and deaths tabulated by birth weight and gestational age from 29 European countries/regions participating in the Euro-Peristat project were used to compute fetal and neonatal mortality rates using cut-offs of 1000-grams and 28-weeks (2.8 million total births). We measured differences in rates between and within countries using the Wilcoxon signed rank test and 95% confidence intervals, respectively.Principal findingsFor fetal mortality, rates based on gestational age were significantly higher than those based on birth weight (p<0.001), although these differences varied between countries. The use of a 1000-gram threshold included 8823 fetal deaths compared with 9535 using a 28-week threshold (difference of 712). In contrast, the choice of a cut-off made little difference for comparisons of neonatal deaths (difference of 16). Neonatal mortality rates differed minimally, by under 0.1 per 1000 in most countries (p = 0.370). Country rankings were comparable with both thresholds.ConclusionsNeonatal mortality rates were not affected by the choice of a threshold. However, the use of a 1000-gram threshold underestimated the health burden of fetal deaths. This may in part reflect the exclusion of growth restricted fetuses. In high-income countries with a good measure of gestational age, using a 28-week threshold may provide additional valuable information about fetal deaths occurring in the third trimester.

Project description:BackgroundSmall-for-gestational-age (SGA) and preterm births are associated with adverse health consequences, including neonatal and infant mortality, childhood undernutrition, and adulthood chronic disease.ObjectivesThe specific aims of this study were to estimate the association between short maternal stature and outcomes of SGA alone, preterm birth alone, or both, and to calculate the population attributable fraction of SGA and preterm birth associated with short maternal stature.MethodsWe conducted an individual participant data meta-analysis with the use of data sets from 12 population-based cohort studies and the WHO Global Survey on Maternal and Perinatal Health (13 of 24 available data sets used) from low- and middle-income countries (LMIC). We included those with weight taken within 72 h of birth, gestational age, and maternal height data (n = 177,000). For each of these studies, we individually calculated RRs between height exposure categories of < 145 cm, 145 to < 150 cm, and 150 to < 155 cm (reference: ≥ 155 cm) and outcomes of SGA, preterm birth, and their combination categories. SGA was defined with the use of both the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st) birth weight standard and the 1991 US birth weight reference. The associations were then meta-analyzed.ResultsAll short stature categories were statistically significantly associated with term SGA, preterm appropriate-for-gestational-age (AGA), and preterm SGA births (reference: term AGA). When using the INTERGROWTH-21st standard to define SGA, women < 145 cm had the highest adjusted risk ratios (aRRs) (term SGA-aRR: 2.03; 95% CI: 1.76, 2.35; preterm AGA-aRR: 1.45; 95% CI: 1.26, 1.66; preterm SGA-aRR: 2.13; 95% CI: 1.42, 3.21). Similar associations were seen for SGA defined by the US reference. Annually, 5.5 million term SGA (18.6% of the global total), 550,800 preterm AGA (5.0% of the global total), and 458,000 preterm SGA (16.5% of the global total) births may be associated with maternal short stature.ConclusionsApproximately 6.5 million SGA and/or preterm births in LMIC may be associated with short maternal stature annually. A reduction in this burden requires primary prevention of SGA, improvement in postnatal growth through early childhood, and possibly further intervention in late childhood and adolescence. It is vital for researchers to broaden the evidence base for addressing chronic malnutrition through multiple life stages, and for program implementers to explore effective, sustainable ways of reaching the most vulnerable populations.

Project description:BackgroundIreland introduced a comprehensive workplace smoke-free legislation in March, 2004. Smoking-related adverse birth outcomes have both health care and societal cost implications. The main aim of this study was to determine the impact of the Irish smoke-free legislation on small-for-gestationa- age (SGA) births.Methods and findingsWe developed a population-based birthweight (BW) percentile curve based on a recent study to compute SGA (BW <5(th) percentile) and very SGA (vSGA - BW<3(rd) percentile) for each gestational week. Monthly births born between January 1999 and December 2008 were analyzed linking with monthly maternal smoking rates from a large referral maternity university hospital. We ran individual control and CUSUM charts, with bootstrap simulations, to pinpoint the breakpoint for the impact of ban implementation ( = April 2004). Monthly SGA rates (%) before and after April 2004 was considered pre and post ban period births, respectively. Autocorrelation was tested using Durbin Watson (DW) statistic. Mixed models using a random intercept and a fixed effect were employed using SAS (v 9.2). A total of 588,997 singleton live-births born between January 1999 and December 2008 were analyzed. vSGA and SGA monthly rates declined from an average of 4.7% to 4.3% and from 6.9% to 6.6% before and after April 2004, respectively. No auto-correlation was detected (DW = ~2). Adjusted mixed models indicated a significant decline in both vSGA and SGA rates immediately after the ban [(-5.3%; 95% CI -5.43% to -5.17%, p<0.0001) and (-0.45%; 95% CI: -0.7% to -0.19%, p<0.0007)], respectively. Significant gradual effects continued post the ban periods for vSGA and SGA rates, namely, -0.6% (p<0.0001) and -0.02% (p<0.0001), respectively.ConclusionsA significant reduction in small-for-gestational birth rates both immediately and sustained over the post-ban period, reinforces the mounting evidence of the positive health effect of a successful comprehensive smoke-free legislation in a vulnerable population group as pregnant women.

Project description:BackgroundBabies with low birthweight (<2500 g) are at increased risk of early mortality. However, low birthweight includes babies born preterm and with fetal growth restriction, and not all these infants have a birthweight less than 2500 g. We estimated the neonatal and infant mortality associated with these two characteristics in low-income and middle-income countries.MethodsFor this pooled analysis, we searched all available studies and identified 20 cohorts (providing data for 2,015,019 livebirths) from Asia, Africa, and Latin America that recorded data for birthweight, gestational age, and vital statistics through 28 days of life. Study dates ranged from 1982 through to 2010. We calculated relative risks (RR) and risk differences (RD) for mortality associated with preterm birth (<32 weeks, 32 weeks to <34 weeks, 34 weeks to <37 weeks), small-for-gestational-age (SGA; babies with birthweight in the lowest third percentile and between the third and tenth percentile of a US reference population), and preterm and SGA combinations.FindingsPooled overall RRs for preterm were 6·82 (95% CI 3·56-13·07) for neonatal mortality and 2·50 (1·48-4·22) for post-neonatal mortality. Pooled RRs for babies who were SGA (with birthweight in the lowest tenth percentile of the reference population) were 1·83 (95% CI 1·34-2·50) for neonatal mortality and 1·90 (1·32-2·73) for post-neonatal mortality. The neonatal mortality risk of babies who were both preterm and SGA was higher than that of babies with either characteristic alone (15·42; 9·11-26·12).InterpretationMany babies in low-income and middle-income countries are SGA. Preterm birth affects a smaller number of neonates than does SGA, but is associated with a higher mortality risk. The mortality risks associated with both characteristics extend beyond the neonatal period. Differentiation of the burden and risk of babies born preterm and SGA rather than with low birthweight could guide prevention and management strategies to speed progress towards Millennium Development Goal 4--the reduction of child mortality.FundingBill & Melinda Gates Foundation.

Project description:ObjectivesTo develop consensus statements regarding the regional-level or district-level distribution of surgical services in low and middle-income countries (LMICs) and prioritisation of service scale-up.DesignThis work was conducted using a modified Delphi consensus process. Initial statements were developed by the International Standards and Guidelines for Quality Safe Surgery and Anesthesia Working Group of the Global Alliance for Surgical, Obstetric, Trauma and Anesthesia Care (G4 Alliance) and the International Society of Surgery based on previously published literature and clinical expertise. The Guidance on Conducting and REporting DElphi Studies framework was applied.SettingThe Working Group convened in Suva, Fiji for a meeting hosted by the Ministry of Health and Medical Services to develop the initial statements. Local experts were invited to participate. The modified Delphi process was conducted through an electronically administered anonymised survey.ParticipantsExpert LMIC surgeons were nominated for participation in the modified Delphi process based on criteria developed by the Working Group.Primary outcome measuresThe consensus panel voted on statements regarding the organisation of surgical services, principles for scale-up and prioritisation of scale-up. Statements reached consensus if there was ≥80% agreement among participants.ResultsFifty-three nominated experts from 27 LMICs voted on 27 statements in two rounds. Ultimately, 26 statements reached consensus and comprise the current recommendations. The statements covered three major themes: which surgical services should be decentralised or regionalised; how the implementation of these services should be prioritised; and principles to guide LMIC governments and international visiting teams in scaling up safe, accessible and affordable surgical care.ConclusionsThese recommendations represent the first step towards the development of international guidelines for the scaling up of surgical services in LMICs. They constitute the best available basis for policymaking, planning and allocation of resources for strengthening surgical systems.

Project description:ObjectivesIncreasing access to skilled birth attendance, usually via childbirth in health facilities, is a key intervention to reduce maternal and perinatal mortality and morbidity. Yet, in some countries of sub-Saharan Africa, the uptake is <50%. Age and parity are determinants of facility-based delivery, but are strongly correlated in high fertility settings. This analysis assessed the independent effect of age on facility-based delivery by restricting to first-order births. It was hypothesised that older first-time mothers in this setting might have lower uptake of facility-based deliveries than women in the most common age groups for first birth.SettingThe most recent Demographic and Health Surveys from 34 sub-Saharan African countries were used to assess women's delivery locations.Participants72 772 women having their first birth in the 5 years preceding the surveys were included in the analysis.Primary and secondary outcome measuresProportions and 95% CIs of facility-based deliveries were estimated overall and by country. Multivariable logistic regression was used to calculate the odds of facility-based delivery for different maternal age groups (15-19, 20-24 and ≥25 years) for a pooled sample of all countries.Results59.9% of women had a facility-based delivery for their first birth (95% CI 58.6 to 61.2), ranging from 19.4% in Chad to 96.6% in Rwanda. Compared with women aged 15-19 years, the adjusted odds of having a facility-based delivery for those aged 20-24 was 1.4 (95% CI 1.3 to 1.5, p<0.001) and for those aged ≥25, 1.9 (95% CI 1.6 to 2.2, p<0.001).ConclusionsOlder age at first birth was independently associated with significantly higher odds of facility-based delivery. This went against the hypothesis. Further mixed-method research is needed to explore how increased age improves uptake of facility-based delivery. Promoting facility-based delivery, while ensuring quality of care, should be prioritised to improve birth outcomes in sub-Saharan Africa.

Project description:BackgroundNational estimates for the numbers of babies born small for gestational age and the comorbidity with preterm birth are unavailable. We aimed to estimate the prevalence of term and preterm babies born small for gestational age (term-SGA and preterm-SGA), and the relation to low birthweight (<2500 g), in 138 countries of low and middle income in 2010.MethodsSmall for gestational age was defined as lower than the 10th centile for fetal growth from the 1991 US national reference population. Data from 22 birth cohort studies (14 low-income and middle-income countries) and from the WHO Global Survey on Maternal and Perinatal Health (23 countries) were used to model the prevalence of term-SGA births. Prevalence of preterm-SGA infants was calculated from meta-analyses.FindingsIn 2010, an estimated 32·4 million infants were born small for gestational age in low-income and middle-income countries (27% of livebirths), of whom 10·6 million infants were born at term and low birthweight. The prevalence of term-SGA babies ranged from 5·3% of livebirths in east Asia to 41·5% in south Asia, and the prevalence of preterm-SGA infants ranged from 1·2% in north Africa to 3·0% in southeast Asia. Of 18 million low-birthweight babies, 59% were term-SGA and 41% were preterm-SGA. Two-thirds of small-for-gestational-age infants were born in Asia (17·4 million in south Asia). Preterm-SGA babies totalled 2·8 million births in low-income and middle-income countries. Most small-for-gestational-age infants were born in India, Pakistan, Nigeria, and Bangladesh.InterpretationThe burden of small-for-gestational-age births is very high in countries of low and middle income and is concentrated in south Asia. Implementation of effective interventions for babies born too small or too soon is an urgent priority to increase survival and reduce disability, stunting, and non-communicable diseases.FundingBill & Melinda Gates Foundation by a grant to the US Fund for UNICEF to support the activities of the Child Health Epidemiology Reference Group (CHERG).

Dataset Information

International variations in the gestational age distribution of births: an ecological study in 34 high-income countries.

Publications

International variations in the gestational age distribution of births: an ecological study in 34 high-income countries.

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