Factors associated with preterm birth in Cardiff, Wales. II. Indicated and spontaneous preterm birth

Prevalence of Asymptomatic Bacteriuria (ASB) in Pregnant Women in India: A Systematic Review and Meta-Analysis

Background

Asymptomatic bacteriuria is prevalent during pregnancy. If it goes undetected, it can lead to urinary tract infection with severe maternal and neonatal complications. Until date, India does not have any guidelines to test for ASB during pregnancy.

Objective

To estimate the pooled prevalence of asymptomatic bacteriuria in pregnant women at national level in India.

Material and Methods

We searched Medline, Embase, Web of Science, and Google Scholar using search strategy with keyword. Two authors independently assessed the eligibility of study. The checklist of the JBI was used for evaluating the quality of reporting. The extracted data were analyzed, and the results were reported using a random-effects model with 95% confidence interval (CI). Subgroup analysis was conducted for zones of India, parity and trimester. Publication bias is reported as funnel plot.

Result

Pooled prevalence of asymptomatic bacteriuria among pregnant women in India is 13.5% [CI 11.1; 15.8]. Subgroup analysis based on the various geographic zones of the country the pooled prevalence ranged from 9.2% in central zone to 14.8% in south zone. Distribution of prevalence of ASB as per parity was approximately identical. The prevalence of ASB was found to be high in third (21.8%).

Conclusion

The prevalence of ASB is found to be high among Indian pregnant women, especially in third trimester. It is therefore recommended for guideline to screen and treat every pregnant woman for ASB to prevent further complications.

Prediction of Preterm Birth among Infants with Orofacial Cleft Defects

OBJECTIVE

To develop risk prediction models for preterm birth among infants with orofacial clefts.

DESIGN

Data from the Texas Birth Defects Registry for infants with orofacial clefts born between 1999-2014 were used to develop preterm birth predictive models. Logistic regression was used to consider maternal and infant characteristics, and internal validation of the final model was performed using bootstrapping methods. The area under the curve (AUC) statistic was generated to assess model performance, and separate predictive models were built and validated for infants with cleft lip and cleft palate alone. Several secondary analyses were conducted among subgroups of interest.

SETTING

State-wide, population-based Registry data.

PATIENTS/PARTICIPANTS

6774 infants with orofacial clefts born in Texas between 1999-2014.

MAIN OUTCOME MEASURE(S)

Preterm birth among infants with orofacial clefts.

RESULTS

The final predictive model performed modestly, with an optimism-corrected AUC of 0.67 among all infants with orofacial clefts. The optimism-corrected models for cleft lip (with or without cleft palate) and cleft palate alone had similar predictive capability, with AUCs of 0.66 and 0.67, respectively. Secondary analyses had similar results, but the model among infants with delivery prior to 32 weeks demonstrated higher optimism-corrected predictive capability (AUC = 0.74).

CONCLUSIONS

This study provides a first step towards predicting preterm birth risk among infants with orofacial clefts. Identifying pregnancies affected by orofacial clefts at the highest risk for preterm birth may lead to new avenues for improving outcomes among these infants.

Associations of Preterm Birth with Dental and Gastrointestinal Diseases: Machine Learning Analysis Using National Health Insurance Data

BACKGROUND

This study uses machine learning with large-scale population data to assess the associations of preterm birth (PTB) with dental and gastrointestinal diseases.

METHODS

Population-based retrospective cohort data came from Korea National Health Insurance claims for 124,606 primiparous women aged 25-40 and delivered in 2017. The 186 independent variables included demographic/socioeconomic determinants, disease information, and medication history. Machine learning analysis was used to establish the prediction model of PTB. Random forest variable importance was used for identifying major determinants of PTB and testing its associations with dental and gastrointestinal diseases, medication history, and socioeconomic status.

RESULTS

The random forest with oversampling data registered an accuracy of 84.03, and the areas under the receiver-operating-characteristic curves with the range of 84.03-84.04. Based on random forest variable importance with oversampling data, PTB has strong associations with socioeconomic status (0.284), age (0.214), year 2014 gastroesophageal reflux disease (GERD) (0.026), year 2015 GERD (0.026), year 2013 GERD (0.024), progesterone (0.024), year 2012 GERD (0.023), year 2011 GERD (0.021), tricyclic antidepressant (0.020) and year 2016 infertility (0.019). For example, the accuracy of the model will decrease by 28.4%, 2.6%, or 1.9% if the values of socioeconomic status, year 2014 GERD, or year 2016 infertility are randomly permutated (or shuffled).

CONCLUSION

By using machine learning, we established a valid prediction model for PTB. PTB has strong associations with GERD and infertility. Pregnant women need close surveillance for gastrointestinal and obstetric risks at the same time.

Vaginal Microbiota Is Stable and Mainly Dominated by Lactobacillus at Third Trimester of Pregnancy and Active Childbirth: A Longitudinal Study of Ten Mexican Women

In healthy women at reproductive age, the vaginal microbiota is mainly dominated by Lactobacillus bacteria during pregnancy and non-pregnancy stages. However, little is known about longitudinal changes within the vaginal microbiota composition from the third trimester of pregnancy to childbirth in healthy women. Thus, we conducted an exploratory longitudinal study of vaginal microbiota composition of 10 Mexican pregnant women, sampling from the same volunteer at two-time points: third trimester of pregnancy and active childbirth. Vaginal bacterial microbiota was characterized by V3-16S rDNA libraries by high-throughput sequencing and bioinformatics methods. Out of ten, vaginal microbiota from eight women was dominated by the Lactobacillus genus at both time points, whereas the other two women showed vaginal microbiota composition with high abundance of genera Gardnerella, Prevotella, and members of the Atopobiaceae family, without any preterm birth correlation. Importantly, we found no statistically significant differences in relative abundances, absolute reads count, alpha and beta diversity between the third trimester of pregnancy, and active childbirth time points. However, compared to the third trimester of pregnancy, we observed a trend with higher absolute reads counts for Gardnerella, Faecalibaculum, Ileibacterium, and Lactococcus genus at active childbirth and lower absolute reads count of Lactobacillus genus. Our results suggest that the vaginal microbiota composition is stable, and Lactobacillus genus is the dominant taxa in Mexican women's vagina at the third trimester of pregnancy and childbirth.

Uterine fibroids and risk of preterm birth by clinical subtypes: a prospective cohort study

Background

Fibroids are present in approximately one in ten pregnancies and are inconsistently linked with preterm birth. We sought to determine the association between fibroids and preterm birth in a prospective cohort with standardized research ultrasounds for characterizing fibroids in early pregnancy while accounting for the clinical paths that precede preterm birth.

Methods

Participants who were pregnant or planning a pregnancy were recruited from communities in three states between 2000 and 2012. Members of this prospective cohort had a research ultrasound in the first trimester to establish pregnancy dating and to record detailed information about the presence, size, number, and location of fibroids. Baseline information from time of enrollment and a detailed first trimester interview contributed key information about candidate confounders. Birth outcomes, including clinical classification of type of preterm birth (preterm labor, preterm premature rupture of membranes, and medically indicated preterm birth) were cross-validated from participant report, labor and delivery records, and birth certificate data.

Results

Among 4,622 women with singleton pregnancies, 475 had at least one fibroid (10.3%) and 352 pregnancies resulted in preterm birth (7.6%). Prevalence of fibroids was similar for women with preterm and term births (10.2% vs. 10.3%). Fibroids were not associated with increased risk of preterm birth after taking into account confounding (risk ratio adjusted for race/ethnicity and maternal age, 0.88; 95% confidence interval, 0.62–1.24) nor any clinical subtype of preterm birth. No fibroid characteristic or combination of characteristics was associated with risk.

Conclusions

If fibroids increase risk of preterm birth, the effect is substantially smaller than previous estimates. Given lack of effect in a large population of women from the general population, rather than higher risk academic tertiary populations previously most studied, we encourage a reconsideration of the clinical impression that presence of fibroids is a major risk factor for preterm birth.

Landscape of Preterm Birth Therapeutics and a Path Forward

Preterm birth (PTB) remains the leading cause of infant morbidity and mortality. Despite 50 years of research, therapeutic options are limited and many lack clear efficacy. Tocolytic agents are drugs that briefly delay PTB, typically to allow antenatal corticosteroid administration for accelerating fetal lung maturity or to transfer patients to high-level care facilities. Globally, there is an unmet need for better tocolytic agents, particularly in low- and middle-income countries. Although most tocolytics, such as betamimetics and indomethacin, suppress downstream mediators of the parturition pathway, newer therapeutics are being designed to selectively target inflammatory checkpoints with the goal of providing broader and more effective tocolysis. However, the relatively small market for new PTB therapeutics and formidable regulatory hurdles have led to minimal pharmaceutical interest and a stagnant drug pipeline. In this review, we present the current landscape of PTB therapeutics, assessing the history of drug development, mechanisms of action, adverse effects, and the updated literature on drug efficacy. We also review the regulatory hurdles and other obstacles impairing novel tocolytic development. Ultimately, we present possible steps to expedite drug development and meet the growing need for effective preterm birth therapeutics.

Controversies in the prevention of spontaneous preterm birth in asymptomatic women: an evidence summary and expert opinion

Preterm birth prevention is multifaceted and produces many nuanced questions. This review addresses six important clinical questions about preterm birth prevention as voted for by members of the UK Preterm Clinical Network. The questions cover the following areas: preterm birth prevention in 'low-risk' populations; screening for asymptomatic genital tract infection in women at high risk of preterm birth; cervical length screening with cerclage or vaginal pessary in situ; cervical shortening whilst using progesterone; use of vaginal progesterone in combination with cervical cerclage; and optimal advice about intercourse for women at high risk of preterm birth.

Asymptomatic GBS bacteriuria during antenatal visits: To treat or not to treat?

Inconsistencies persist regarding the efficacy of treating asymptomatic group B Streptococcus bacteriuria in pregnant individuals with colony counts below 10 (100,000) CFU/mL. Despite these discrepancies, treatment still occurs. This article examines the role of screening and treatment, evidence-based guidelines, and practice patterns to provide clarification and resolve local practice disparities.

Low-dose aspirin for the prevention of preterm delivery in nulliparous women with a singleton pregnancy (ASPIRIN): a randomised, double-blind, placebo-controlled trial

BACKGROUND

Preterm birth remains a common cause of neonatal mortality, with a disproportionately high burden in low-income and middle-income countries. Meta-analyses of low-dose aspirin to prevent pre-eclampsia suggest that the incidence of preterm birth might also be decreased, particularly if initiated before 16 weeks of gestation.

METHODS

ASPIRIN was a randomised, multicountry, double-masked, placebo-controlled trial of low-dose aspirin (81 mg daily) initiated between 6 weeks and 0 days of pregnancy, and 13 weeks and 6 days of pregnancy, in nulliparous women with an ultrasound confirming gestational age and a singleton viable pregnancy. Participants were enrolled at seven community sites in six countries (two sites in India and one site each in the Democratic Republic of the Congo, Guatemala, Kenya, Pakistan, and Zambia). Participants were randomly assigned (1:1, stratified by site) to receive aspirin or placebo tablets of identical appearance, via a sequence generated centrally by the data coordinating centre at Research Triangle Institute International (Research Triangle Park, NC, USA). Treatment was masked to research staff, health providers, and patients, and continued until 36 weeks and 7 days of gestation or delivery. The primary outcome of incidence of preterm birth, defined as the number of deliveries before 37 weeks' gestational age, was analysed in randomly assigned women with pregnancy outcomes at or after 20 weeks, according to a modified intention-to-treat (mITT) protocol. Analyses of our binary primary outcome involved a Cochran-Mantel-Haenszel test stratified by site, and generalised linear models to obtain relative risk (RR) estimates and associated confidence intervals. Serious adverse events were assessed in all women who received at least one dose of drug or placebo. This study is registered with ClinicalTrials.gov, NCT02409680, and the Clinical Trial Registry-India, CTRI/2016/05/006970.

FINDINGS

From March 23, 2016 to June 30, 2018, 14 361 women were screened for inclusion and 11 976 women aged 14-40 years were randomly assigned to receive low-dose aspirin (5990 women) or placebo (5986 women). 5780 women in the aspirin group and 5764 in the placebo group were evaluable for the primary outcome. Preterm birth before 37 weeks occurred in 668 (11·6%) of the women who took aspirin and 754 (13·1%) of those who took placebo (RR 0·89 [95% CI 0·81 to 0·98], p=0·012). In women taking aspirin, we also observed significant reductions in perinatal mortality (0·86 [0·73-1·00], p=0·048), fetal loss (infant death after 16 weeks' gestation and before 7 days post partum; 0·86 [0·74-1·00], p=0·039), early preterm delivery (<34 weeks; 0·75 [0·61-0·93], p=0·039), and the incidence of women who delivered before 34 weeks with hypertensive disorders of pregnancy (0·38 [0·17-0·85], p=0·015). Other adverse maternal and neonatal events were similar between the two groups.

INTERPRETATION

In populations of nulliparous women with singleton pregnancies from low-income and middle-income countries, low-dose aspirin initiated between 6 weeks and 0 days of gestation and 13 weeks and 6 days of gestation resulted in a reduced incidence of preterm delivery before 37 weeks, and reduced perinatal mortality.

FUNDING

Eunice Kennedy Shriver National Institute of Child Health and Human Development.

The State of the Science of Preterm Birth: Assessing Contemporary Screening and Preventive Strategies

Preterm birth remains a leading cause of morbidity and mortality during the perinatal and neonatal periods. Now affecting approximately 1 in 10 births in the United States, preterm birth often occurs spontaneously and without a clear etiology. Careful assessment of risk factors, however, identifies vulnerable women allowing targeted interventions such as progestogen therapy and cerclage. This article is intended to highlight preterm birth risk factors and current predictive and preventive strategies for midwives, nurse practitioners, clinical nurse specialists, and perinatal nurses.

Antibiotics for asymptomatic bacteriuria in pregnancy

BACKGROUND

Asymptomatic bacteriuria is a bacterial infection of the urine without any of the typical symptoms that are associated with a urinary infection, and occurs in 2% to 15% of pregnancies. If left untreated, up to 30% of mothers will develop acute pyelonephritis. Asymptomatic bacteriuria has been associated with low birthweight and preterm birth. This is an update of a review last published in 2015.

OBJECTIVES

To assess the effect of antibiotic treatment for asymptomatic bacteriuria on the development of pyelonephritis and the risk of low birthweight and preterm birth.

SEARCH METHODS

For this update, we searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) on 4 November 2018, and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCT) comparing antibiotic treatment with placebo or no treatment in pregnant women with asymptomatic bacteriuria found on antenatal screening. Trials using a cluster-RCT design and quasi-RCTs were eligible for inclusion, as were trials published in abstract or letter form, but cross-over studies were not.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data, and checked for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We included 15 studies, involving over 2000 women. Antibiotic treatment compared with placebo or no treatment may reduce the incidence of pyelonephritis (average risk ratio (RR) 0.24, 95% confidence interval (CI) 0.13 to 0.41; 12 studies, 2017 women; low-certainty evidence). Antibiotic treatment may be associated with a reduction in the incidence of preterm birth (RR 0.34, 95% CI 0.13 to 0.88; 3 studies, 327 women; low-certainty evidence), and low birthweight babies (average RR 0.64, 95% CI 0.45 to 0.93; 6 studies, 1437 babies; low-certainty evidence). There may be a reduction in persistent bacteriuria at the time of delivery (average RR 0.30, 95% CI 0.18 to 0.53; 4 studies; 596 women), but the results were inconclusive for serious adverse neonatal outcomes (average RR 0.64, 95% CI 0.23 to 1.79, 3 studies; 549 babies). There were very limited data on which to estimate the effect of antibiotics on other infant outcomes, and maternal adverse effects were rarely described. Overall, we judged only one trial at low risk of bias across all domains; the other 14 studies were assessed as high or unclear risk of bias. Many studies lacked an adequate description of methods, and we could only judge the risk of bias as unclear, but in most studies, we assessed at least one domain at high risk of bias. We assessed the quality of the evidence for the three primary outcomes with GRADE software, and found low-certainty evidence for pyelonephritis, preterm birth, and birthweight less than 2500 g.

AUTHORS' CONCLUSIONS

Antibiotic treatment may be effective in reducing the risk of pyelonephritis in pregnancy, but our confidence in the effect estimate is limited given the low certainty of the evidence. There may be a reduction in preterm birth and low birthweight with antibiotic treatment, consistent with theories about the role of infection in adverse pregnancy outcomes, but again, the confidence in the effect is limited given the low certainty of the evidence. Research implications identified in this review include the need for an up-to-date cost-effectiveness evaluation of diagnostic algorithms, and more evidence to learn whether there is a low-risk group of women who are unlikely to benefit from treatment of asymptomatic bacteriuria.

Screening for Asymptomatic Bacteriuria in Adults: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Screening for asymptomatic bacteriuria can identify patients for whom treatment might be beneficial for preventing symptomatic infection and other health outcomes.

OBJECTIVE

To systematically review benefits and harms of asymptomatic bacteriuria screening and treatment in adults, including during pregnancy, to inform the US Preventive Services Task Force.

DATA SOURCES

MEDLINE, PubMed (publisher-supplied records), and Cochrane Collaboration Central Registry of Controlled Trials; surveillance through May 24, 2019.

STUDY SELECTION

Randomized clinical trials (RCTs) and observational studies on benefits and harms of screening for asymptomatic bacteriuria; RCTs on benefits and harms of asymptomatic bacteriuria treatment. Eligible populations included unselected, asymptomatic individuals without known urinary tract conditions.

DATA EXTRACTION AND SYNTHESIS

Independent critical appraisal and data abstraction by 2 reviewers. Random-effects meta-analysis was conducted to estimate benefits of the interventions.

MAIN OUTCOMES AND MEASURES

Symptomatic infection; function, morbidity, mortality; pregnancy complications and birth outcomes.

RESULTS

Nineteen studies (N = 8443) meeting inclusion criteria were identified. Two cohort studies (n = 5289) found fewer cases of pyelonephritis in the cohorts of screened pregnant women (0.5%) than within retrospective comparisons of unscreened cohorts (2.2% and 1.8%); the larger study estimated a statistically significant relative risk of 0.30 (95% CI, 0.15-0.60). No studies examined screening in nonpregnant populations. Among 12 trials of asymptomatic bacteriuria screening and treatment during pregnancy (n = 2377; 1 conducted within past 30 years), there were reduced rates of pyelonephritis (range, 0%-16.5% for the intervention group and 2.2%-36.4% for the control group; pooled risk ratio [RR], 0.24 [95% CI, 0.14-0.40]; 12 trials) and low birth weight (range, 2.5%-14.8% for the intervention group and 6.7%-21.4% for the control group; pooled RR, 0.64 [95% CI, 0.46-0.90]; 7 trials). There was no significant difference in infant mortality (pooled RR, 0.98 [95% CI, 0.29-3.26]; 6 trials). Five RCTs of asymptomatic bacteriuria treatment in nonpregnant adults (n = 777) did not report any significant differences in risk of infection, mobility, or mortality. Limited evidence on harms of screening or treatment was available, and no statistically significant differences were identified.

CONCLUSIONS AND RELEVANCE

Screening and treatment for asymptomatic bacteriuria during pregnancy was associated with reduced rates of pyelonephritis and low birth weights, but the available evidence was not current, with only 1 study conducted in the past 30 years. Benefits of asymptomatic bacteriuria treatment in nonpregnant adult populations were not found. Trial evidence on harms of asymptomatic bacteriuria antibiotic treatment was limited.

Prevention and Therapy of Preterm Birth. Guideline of the DGGG, OEGGG and SGGG (S2k Level, AWMF Registry Number 015/025, February 2019) - Part 1 with Recommendations on the Epidemiology, Etiology, Prediction, Primary and Secondary Prevention of Preterm Birth

Aims This is an official guideline of the German Society for Gynecology and Obstetrics (DGGG), the Austrian Society for Gynecology and Obstetrics (ÖGGG) and the Swiss Society for Gynecology and Obstetrics (SGGG). The aim of this guideline is to improve the prediction, prevention and management of preterm birth based on evidence obtained from recent scientific literature, the experience of the members of the guideline commission and the views of self-help groups. Methods Based on the international literature, the members of the participating medical societies and organizations developed Recommendations and Statements. These were adopted following a formal process (structured consensus conference with neutral moderation, voting was done in writing using the Delphi method to achieve consensus). Recommendations Part I of this short version of the guideline lists Statements and Recommendations on the epidemiology, etiology, prediction and primary and secondary prevention of preterm birth.

The Impact of CenteringPregnancy Group Prenatal Care on Birth Outcomes in Medicaid Eligible Women

Background: CenteringPregnancy group prenatal care (GPNC) has been shown to reduce rates of preterm birth (PTB). We evaluated the impact of GPNC on spontaneous PTB (sPTB) as a first step in exploring the possible mechanism by which GPNC may decrease rates of PTB. We also evaluated whether attending more than five GPNC sessions affected PTB risk and examined all differences by race/ethnicity. Materials and Methods: We conducted a retrospective cohort study among women delivering at a single institution between April 2009 and March 2014. Birth outcome data from vital statistics records were appended to patient records, and detailed chart abstraction was used to determine spontaneous versus indicated PTB. The association between GPNC and attending more than five GPNC sessions and birth outcomes (i.e., PTB, sPTB, low birth weight [LBW], and neonatal intensive care unit [NICU] admissions) was analyzed using generalized estimating equation log binomial regression models. We examined effect modification of the associations by race/ethnicity. Results: The analysis included 1,292 women in GPNC and 8,703 in traditional individual prenatal care (IPNC). After controlling for potential confounders, the risk of PTB (risk ratio [RR] 0.38; 95% confidence interval [CI] 0.31-0.47), sPTB (RR 0.49; 95% CI 0.38-0.63), LBW (RR 0.46; 95% CI 0.37-0.56), and NICU admissions (RR 0.46; 95% CI 0.37-0.57) was lower in GPNC compared to IPNC women. Results differed by maternal race/ethnicity, with the strongest associations among non-Hispanic white mothers and the weakest associations among Hispanic mothers, especially for sPTB. Similarly, the risk of PTB, LBW, and NICU admissions was lower among GPNC women who attended more than five sessions. Conclusion: Participation in GPNC demonstrated a decreased risk for sPTB, as well as other adverse birth outcomes. In addition, participation in more than five GPNC sessions demonstrated a decreased risk for adverse birth outcomes. Prospective longitudinal studies are needed to further explore mechanisms associated with these findings.

The trends and associated factors of preterm deliveries from 2001 to 2011 in Taiwan

The rate of preterm birth has been increasing worldwide. Most preterm babies are at increased risk of central nervous system impairments as well as respiratory and gastrointestinal complications. The aim of this study was to investigate the trends in preterm birth and associated factors contributing to preterm delivery in Taiwan. Information on obstetric antecedents and risk factors of preterm birth of pregnant women was obtained from the Taiwan National Medical Birth Register database. All live births from 2001 to 2011 in Taiwan were included in this study. A total of 2,334,532 live births from 2001 to 2011 were included in this study. Overall, the proportion of preterm deliveries increased by 11.1% (from 8.2% in 2001 to 9.1% in 2011). Multiple logistic regression analyses showed that nulliparity, multiple births, maternal medical complications, maternal age <20 years or ≥40 years, and medical indication for earlier delivery were positively associated with an increased risk of preterm delivery. Nulliparous women aged younger than 20 years and older than 40 years should be recognized as at-risk for preterm birth.

The effect of pregnancy induced hypertension and multiple pregnancies on preterm birth in Ethiopia: a systematic review and meta-analysis

Objective

This systematic review and meta-analysis aimed to estimate the overall pooled prevalence of preterm birth and the effect of pregnancy induced hypertension (PIH) and multiple pregnancies on preterm birth in Ethiopia.

Result

A total of 9 studies with 27,119 participants were included in this systematic review and meta-analysis. The pooled prevalence of preterm birth among mothers who gave births in Ethiopia was found to be 13.32% (95% CI = 7.99, 18.660). Preterm birth was found to be higher among mothers who had pregnancy induced hypertension with odds ratio of 4.69 (95% CI = 2.32, 9.49) and multiple pregnancy with odds ratio of 2.40 (95% CI = 1.06, 5.45) as compared to the counterparts. In subgroup analysis by region, the prevalence of preterm birth was found to be 12.63% (95% CI = 3.26, 22) in Amhara and 10.18% (95% CI = 6.04, 14.32) in Oromia region.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4128-0) contains supplementary material, which is available to authorized users.

Effect of maternal origin on the association between maternal height and risk of preterm birth in Belgium: a retrospective observational cohort study

OBJECTIVES

To investigate the effect of maternal origin on the association between maternal height and the risk of preterm birth (PTB).

DESIGN

Retrospective observational cohort study.

SETTING

Two of the three Belgian regions, including Brussels-Capital and Walloon regions.

PARTICIPANTS

A total of 245 204 women spontaneously delivered live singletons between 2009 and 2013. Maternal nationality at the time of birth included Belgium, Congo, French, Italy, Morocco, Poland, Romania and Turkey.

OUTCOMES MEASURES

The outcome variable was spontaneous PTB, defined as childbirth occurring at less than 37 weeks' gestation.

RESULTS

Average height, demographic characteristics and the spontaneous PTB rate differed according to maternal origin, defined as maternal nationality at birth. The pattern of association between maternal height and the risk of PTB was not uniform by maternal nationality at birth. The low maternal height category was associated with a statistically significant increased risk of spontaneous PTB for Belgian (adjusted OR (aOR) 1.23, 95% CI 1.16 to 1.32), Italian (aOR 1.48, 95% CI 1.12 to 1.96) and Polish (aOR 1.76, 95% CI 1.11 to 2.78), respectively. However, this association was not observed for the women from Congo, France, Morocco, Romania and Turkey.

CONCLUSIONS

The association between height and the risk of PTB was modified by maternal nationality, even for mothers from the same region of the world. For example, there was a significant inverse association for the Belgians and Italians but not for French women. Our data suggest that PTB risk assessment should take into account the specific height of maternal origin.

Interpregnancy Interval and Adverse Perinatal Outcomes: A Record-Linkage Study Using the Manitoba Population Research Data Repository

OBJECTIVE

To examine the association between the interpregnancy interval (IPI) and preterm birth, low birth weight, and SGA birth in a developed country with universal health coverage.

METHODS

We conducted a secondary analysis of data housed at the Manitoba Centre for Health Policy. All live births in Manitoba hospitals over a 29-year period were identified and consecutive births to the same mother were grouped into sibling pairs to calculate the IPI for the younger siblings. Logistic regression models were fit to examine the association between the IPI and adverse perinatal outcomes, adjusted for potentially confounding sociodemographic and clinical factors.

RESULTS

In a cohort of more than 171 000 births and relative to IPIs of 18 to 23 months, IPIs shorter than 12 and longer than 23 months were associated with significantly increased odds of preterm birth overall and both medically indicated and spontaneous preterm births, low birth weight, and SGA birth. The strongest association observed was for intervals shorter than 6 months and spontaneous preterm birth (adjusted OR 1.83, 95% CI 1.65-2.03). When the outcome was modelled as GA categories, the strongest association observed was for intervals shorter than 6 months and early preterm birth (<34 weeks' GA; adjusted OR 2.47, 95% CI 2.07-2.94).

CONCLUSION

If the associations observed between the IPI and adverse perinatal outcomes in this large, population-based cohort are causal, birth spacing could form an important target of public health messaging in Canada.

[Epidemiology and risk factors of preterm birth]

OBJECTIVE

To synthesize the available evidence regarding the incidence and several risk factors of preterm birth. To describe neonatal outcomes according to gestational age and to the context of delivery.

MATERIALS AND METHODS

Consultation of the Medline database.

RESULTS

In 2010, 11% of live births (15 million babies) occurred before 37 completed weeks of gestation worldwide. About 85% of these births were moderate to late preterm babies (32-36 weeks), 10% were very preterm babies (28-31 weeks) and 5% were extremely preterm babies (<28 weeks). In France, premature birth concerns 60,000 neonates every year, 12,000 of whom are born before 32 completed weeks of gestation. Half of them are delivered after spontaneous onset of labor or preterm premature rupture of the membranes, and the other half are provider-initiated preterm births. Several maternal factors are associated with preterm birth, including sociodemographic, obstetrical, psychological, and genetic factors; paternal and environmental factors are also involved. Gestational age is highly associated with neonatal mortality and with short- and long-term morbidities. Pregnancy complications and the context of delivery also have an impact on neonatal outcomes.

CONCLUSION

Preterm birth is one of the leading cause of the under-five mortality and of neurodevelopmental impairment worldwide; it remains a major public health issue.

Duration of treatment for asymptomatic bacteriuria during pregnancy

BACKGROUND

A previous Cochrane systematic review has shown that antibiotic drug treatment of asymptomatic bacteriuria in pregnant women substantially decreases the risk of pyelonephritis and reduces the risk of preterm delivery. However, it is not clear whether single-dose therapy is as effective as longer conventional antibiotic treatment.

OBJECTIVES

To assess the effects of different durations of treatment for asymptomatic bacteriuria in pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2015) and reference lists of identified articles.

SELECTION CRITERIA

Randomized and quasi-randomized trials comparing antimicrobial therapeutic regimens that differed in duration (particularly comparing single dose with longer duration regimens) in pregnant women diagnosed with asymptomatic bacteriuria.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We included 13 studies, involving 1622 women. All were comparisons of single-dose treatment with short-course (four- to seven-day) treatments. The risk of bias of trials included in this review was largely unclear, and most trials were at high risk of performance bias. The quality of the evidence was assessed using the GRADE approach. When the any antibiotic agent was used, the 'no cure' rate for asymptomatic bacteriuria in pregnant women was slightly lower for the short-course treatment over the single-dose treatment, although there was evidence of statistical heterogeneity (average risk ratio (RR) 1.28, 95% confidence interval (CI) 0.87 to 1.88; women = 1502, studies = 13; I² = 56%; very low quality evidence). Data from only good quality trials also showed better cure rates with short (four- to seven-day) regimens of the same microbial agent (average RR 1.72, 95% CI 1.27 to 2.33; women = 803, studies = two; I² = 0%; high quality evidence). There was no clear difference in the recurrence of asymptomatic bacteriuria rate between treatment and control groups, whether the same or different microbial agents were used (RR 1.13, 95% CI 0.77 to 1.66; 445 women studies = eight; I² = 0%; very low quality evidence). Differences were detected for low birthweight babies, favoring a short course (four- to seven-day treatment) of the same microbial agent, although the data come from a single trial (RR 1.65, 95% CI 1.06 to 2.57; 714 women; high quality evidence), but no differences were observed for preterm delivery (RR 1.17, 95% CI 0.77 to 1.78; women = 804; studies = three; I² = 23%; moderate quality) or pyelonephritis (RR 3.09, 95% CI 0.54 to 17.55; women = 102; studies = two; I² = 0%; very low quality evidence). Finally, single-dose treatment of any microbial agent was associated with a decrease in reports of 'any side effects' (RR 0.70, 95% CI 0.56 to 0.88; 1460 women, studies = 12; I² = 9%; low quality evidence). Evidence was downgraded for risk of bias concerns in trials contributing data and for imprecise effect estimates (wide confidence intervals crossing the line of no effect, and in some cases, small studies with few events).

AUTHORS' CONCLUSIONS

A single-dose regimen of antibiotics may be less effective than a short-course (four- to seven-day) regimen, but more evidence is needed from large trials measuring important outcomes, such as cure rate. Women with asymptomatic bacteriuria in pregnancy should be treated by the standard regimen of antibiotics until more data become available testing seven-day treatment compared with shorter courses of three- or five-day regimens.

Effects of race/ethnicity and BMI on the association between height and risk for spontaneous preterm birth

OBJECTIVE

Short height and obesity have each been associated with increased risk for preterm birth (PTB). However, the effect of short height on PTB risk, across different race/ethnicities and body mass index (BMI) categories, has not been studied. Our objective was to determine the influence of maternal height on the risk for PTB within race/ethnic groups, BMI groups, or adjusted for weight.

STUDY DESIGN

All California singleton live births from 2007 through 2010 were included from birth certificate data (vital statistics) linked to hospital discharge data. Prepregnancy BMI (kg/m(2)) was categorized as underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), or obese (≥30.0). Maternal race/ethnicity was categorized as: non-Hispanic white, non-Hispanic black, Hispanic, and Asian. Maternal height was classified into 5 categories (shortest, short, middle, tall, tallest) based on racial/ethnic-specific height distributions, with the middle category serving as reference. Poisson regression models were used to estimate relative risks for the association between maternal height and risk of spontaneous PTB (<37 weeks and <32 weeks). Models were stratified on race/ethnicity and BMI. Generalized additive regression models were used to detect nonlinearity of the association. Covariates considered were: maternal age, weight, parity, prenatal care, education, medical payment, previous PTB, gestational and pregestational diabetes, pregestational hypertension, preeclampsia/eclampsia, and smoking.

RESULTS

Among 1,655,385 California singleton live births, 5.2% were spontaneous PTB <37 weeks. Short stature (first height category) was associated with increased risk for PTB for non-Hispanic whites and Hispanics across all BMI categories. Among obese women, tall stature (fifth category) was associated with reduced risk for spontaneous PTB for non-Hispanic whites, Asians, and Hispanics. The same pattern of association was seen for height and risk for spontaneous PTB <32 weeks. In the generalized additive regression model plots, short stature was associated with increased risk for spontaneous PTB of <32 and <37 weeks of gestation among whites and Asians. However, this association was not observed for blacks and Hispanics.

CONCLUSION

Maternal shorter height is associated with a modest increased risk for spontaneous PTB regardless of BMI. Our results suggest that PTB risk assessment should consider race/ethnicity-specific height with respect to the norm in addition to BMI assessment.

Antibiotics for asymptomatic bacteriuria in pregnancy

BACKGROUND

Asymptomatic bacteriuria occurs in 2% to 10% of pregnancies and, if not treated, up to 30% of mothers will develop acute pyelonephritis. Asymptomatic bacteriuria has been associated with low birthweight and preterm birth.

OBJECTIVES

To assess the effect of antibiotic treatment for asymptomatic bacteriuria on the development of pyelonephritis and the risk of low birthweight and preterm birth.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (19 March 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomized trials comparing antibiotic treatment with placebo or no treatment in pregnant women with asymptomatic bacteriuria found on antenatal screening.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.

MAIN RESULTS

Fourteen studies, involving almost 2000 women, were included. Antibiotic treatment compared with placebo or no treatment reduced the incidence of pyelonephritis (average risk ratio (RR) 0.23, 95% confidence interval (CI) 0.13 to 0.41; 11 studies, 1932 women; very low quality evidence). Antibiotic treatment was also associated with a reduction in the incidence of low birthweight babies (average RR 0.64, 95% CI 0.45 to 0.93; six studies, 1437 babies; low quality evidence) and preterm birth (RR 0.27, 95% CI 0.11 to 0.62; two studies, 242 women; low quality evidence). A reduction in persistent bacteriuria at the time of delivery was seen (average RR 0.30, 95% CI 0.18 to 0.53; four studies; 596 women). There were very limited data on which to estimate the effect of antibiotics on other infant outcomes and maternal adverse effects were rarely described.Overall, all 14 studies were assessed as being at high or unclear risk of bias. While many studies lacked an adequate description of methods and the risk of bias could only be assessed as unclear, in almost all studies there was at least one domain where the risk of bias was judged as high. The three primary outcomes were assessed with GRADE software and given a quality rating. Evidence for pyelonephritis, preterm birth and birthweight less than 2500 g was assessed as of low or very low quality.

AUTHORS' CONCLUSIONS

While antibiotic treatment is effective in reducing the risk of pyelonephritis in pregnancy, the estimate of the effect is very uncertain because of the very low quality of the evidence. The reduction in low birthweight and preterm birth with antibiotic treatment is consistent with theories about the role of infection in adverse pregnancy outcomes, but this association should be interpreted with caution given the very poor quality of the included studies.

Preterm birth trend in Taiwan from 2001 to 2009

AIM

The aim of this study was to analyze the trends and risk factors of preterm birth from all the women who delivered during 2001-2009 in Taiwan.

MATERIAL AND METHODS

We analyzed the preterm birth rates, the proportions of obstetric antecedents and risk factors in the population of pregnant women and neonatal Apgar scores according to the National Medical Birth Register database from 2001 to 2009. Adjusted odds ratios (OR) with 95% confidence intervals for risk factors of preterm birth were assessed using multivariable logistic regression models. The obstetric antecedents of preterm birth for singletons were stratified by spontaneous preterm labor and indicated preterm delivery (labor induction or elective cesarean delivery).

RESULTS

The preterm birth rate was 8.56% with the majority (89.76%) delivered between 32 and 37 weeks of gestation. A 0.07% annual increase (P < 0.001) in preterm delivery was observed. The greatest risk factors were multiple pregnancies (OR > 20), followed by medical complications (OR > 2.8), congenital malformations (OR > 2), teen pregnancies (OR > 1), and advanced maternal age (OR > 1). Specifically, singleton preterm births comprised 57.3% spontaneous labor and 42.7% indicated delivery. There was a 0.5% annual increase (P < 0.001) in indicated delivery. Incidence of neonates with poor Apgar scores (<7) was significantly different between those with and without medical complications (P < 0.001).

CONCLUSIONS

The preterm birth rate increased significantly from 2001 to 2009 and multiple pregnancies were the most important contributing factor. Most of the singleton preterm births resulted from spontaneous labor, but the proportion of indicated deliveries increased.

Urinary tract infections in pregnancy: old and new unresolved diagnostic and therapeutic problems

Urinary tract infections (UTIs) are common in pregnant women and pose a great therapeutic challenge, since the risk of serious complications in both the mother and her child is high. Pregnancy is a state associated with physiological, structural and functional urinary tract changes which promote ascending infections from the urethra. Unlike the general population, all pregnant women should be screened for bacteriuria with urine culture, and asymptomatic bacteriuria must be treated in every case that is diagnosed, as it is an important risk factor for pyelonephritis in this population. The antibiotic chosen should have a good maternal and fetal safety profile. In this paper, current principles of diagnosis and management of UTI in pregnancy are reviewed, and the main problems and controversies are identified and discussed.

Biological determinants of spontaneous late preterm and early term birth: a retrospective cohort study

OBJECTIVE

Our aim was to examine the association between biological determinants of preterm birth (infection and inflammation, placental ischaemia and other hypoxia, diabetes mellitus, other) and spontaneous late preterm (34-36 weeks) and early term (37-38 weeks) birth.

DESIGN

Retrospective cohort study.

SETTING

City of London and Middlesex County, Canada.

SAMPLE

Singleton live births, delivered at 34-41 weeks to London-Middlesex mothers following spontaneous labour.

METHODS

Data were obtained from a city-wide perinatal database on births between 2002 and 2011 (n = 17,678). Multivariable analyses used multinomial logistic regression.

MAIN OUTCOME MEASURE

The outcome of interest was the occurrence of late preterm (34-36 weeks) and early term (37-38 weeks) birth, compared with full term birth (39-41 weeks).

RESULTS

After controlling for covariates, there were associations between infection and inflammation and late preterm birth (aOR = 2.07, 95% CI 1.65, 2.60); between placental ischaemia and other hypoxia and late preterm (aOR = 2.21, 95% CI 1.88, 2.61) and early term (aOR = 1.25, 95% CI 1.13, 1.39) birth; between diabetes mellitus and late preterm (aOR = 3.89, 95% CI 2.90, 5.21) and early term (aOR = 2.66, 95% CI 2.19, 3.23) birth; and between other biological determinants (polyhydramnios, oligohydramnios) and late preterm (aOR = 2.81, 95% CI 1.70, 4.64) and early term (aOR = 1.89, 95% CI 1.32, 2.70) birth.

CONCLUSIONS

Our findings show that delivery following spontaneous labour even close to full term may be a result of pathological processes. Because these biological determinants of preterm birth contribute to an adverse intrauterine environment, they have important implications for fetal and neonatal health.

Maternal height and the risk of preterm birth and low birth weight: a systematic review and meta-analyses

OBJECTIVE

Preterm birth (PTB) and low birth weight (LBW) are the leading causes of neonatal morbidity and mortality, but the effect of maternal height on these outcomes continues to be debated. Our objective was to determine the relationships between maternal height and PTB and LBW.

DATA SOURCES

Medline and EMBASE were searched from their inceptions.

STUDY SELECTION

Studies with a reference group that assessed the effect of maternal height on PTB (< 37 weeks) and LBW (< 2500 grams) in singletons were included.

DATA EXTRACTION

Data were extracted independently by two reviewers.

DATA SYNTHESIS

Fifty-six studies were included involving 333 505 women. In the cohort studies, the unadjusted risk of PTB in short-statured women was increased (relative risk [RR] 1.23; 95% CI 1.11 to 1.37), as was the unadjusted risk of LBW (RR 1.81; 95% CI 1.47 to 2.23), although not all of the studies with adjusted data found the same association. Maternal tall stature was not associated with PTB (unadjusted RR 0.97; 95% CI 0.82 to 1.14), although LBW was decreased (unadjusted RR 0.56; 95% CI 0.46 to 0.69), but not in the adjusted data.

CONCLUSION

From our complete systematic review and meta-analyses, to our knowledge the first in this area, we conclude that short-statured women have higher unadjusted risks of PTB and LBW and tall women have approximately one half the unadjusted risk of LBW of women of reference height.

Preterm birth and single nucleotide polymorphisms in cytokine genes

Preterm birth (PTB) is an important issue in neonates because of its complications as well as high morbidity and mortality. The prevalence of PTB is approximately 12-13% in USA and 5-9% in many other developed countries. China represents 7.8% (approximately one million) of 14.9 million babies born prematurely annually worldwide. The rate of PTB is still increasing. Both genetic susceptibility and environmental factors are the major causes of PTB. Inflammation is regarded as an enabling characteristic factor of PTB. The aim of this review is to summarize the current literatures to illustrate the role of single nucleotide polymorphisms (SNPs) of cytokine genes in PTB. These polymorphisms are different among different geographic regions and different races, thus different populations may have different risk factors of PTB. SNPs affect the ability to metabolize poisonous substances and determine inflammation susceptibility, which in turn has an influence on reproduction-related risks and on delivery outcomes after exposure to environmental toxicants and pathogenic organisms.

Effects of socioeconomic position and clinical risk factors on spontaneous and iatrogenic preterm birth

BACKGROUND

The literature shows a variable and inconsistent relationship between socioeconomic position and preterm birth. We examined risk factors for spontaneous and iatrogenic preterm birth, with a focus on socioeconomic position and clinical risk factors, in order to explain the observed inconsistency.

METHODS

We carried out a retrospective population-based cohort study of all singleton deliveries in Nova Scotia from 1988 to 2003. Data were obtained from the Nova Scotia Atlee Perinatal Database and the federal income tax T1 Family Files. Separate logistic models were used to quantify the association between socioeconomic position, clinical risk factors and spontaneous preterm birth and iatrogenic preterm birth.

RESULTS

The study population included 132,714 singleton deliveries and the rate of preterm birth was 5.5%. Preterm birth rates were significantly higher among the women in the lowest (versus the highest) family income group for spontaneous (rate ratio 1.14, 95% confidence interval (CI) 1.03, 1.25) but not iatrogenic preterm birth (rate ratio 0.95, 95% CI 0.75, 1.19). Adjustment for maternal characteristics attenuated the family income-spontaneous preterm birth relationship but strengthened the relationship with iatrogenic preterm birth. Clinical risk factors such as hypertension were differentially associated with spontaneous (rate ratio 3.92, 95% CI 3.47, 4.44) and iatrogenic preterm (rate ratio 14.1, 95% CI 11.4, 17.4) but factors such as diabetes mellitus were not (rate ratio 4.38, 95% CI 3.21, 5.99 for spontaneous and 4.02, 95% CI 2.07, 7.80 for iatrogenic preterm birth).

CONCLUSIONS

Socioeconomic position and clinical risk factors have different effects on spontaneous and iatrogenic preterm. Recent temporal increases in iatrogenic preterm birth appear to be responsible for the inconsistent relationship between socioeconomic position and preterm birth.

Prediction of spontaneous preterm delivery in singleton pregnancies: where are we and where are we going? A review of literature

Prematurity is the chief cause of neonatal morbidity and mortality. The objective of this study is to review the different methods for predicting preterm delivery in asymptomatic pregnant women and in situations of threatened preterm delivery. A search of the PubMed/Medline database was carried out for the years 1980-2012. We included studies for predicting preterm birth in asymptomatic and symptomatic patients. Models for predicting preterm delivery based on maternal factors, cervical length and obstetric history in first trimester of pregnancy is a valuable avenue of research. Nevertheless, prediction accuracy still needs to be improved. In the second and third trimesters, routine digital vaginal examination is of no value in asymptomatic women. Echography of the cervix is not useful except in patients with a history of late miscarriage or preterm delivery in order to offer them a preventive treatment. In symptomatic women, the combination of digital vaginal examination, cervical echography and fibronectin gives the best predictive results. Electromyography of the uterus and elastography of the cervix are interesting avenues for future research. Identifying patients at risk of preterm delivery should be considered differently at each stage of pregnancy.

What is predictive of preterm delivery in the first trimester: isthmus or cervical length?

OBJECTIVE

This study aims to evaluate the utility of first trimester cervical ultrasonography in predicting preterm delivery by separate analysis of measurements of cervical and isthmus length.

METHODS

This is a cohort study based on data collected prospectively on singletons between 1 July 2011 and 1 February 2013. Mean cervical, isthmus and cervico-isthmic complex length were measured for deliveries before and after 37 weeks.

RESULTS

A total of 1494 pregnancies were analysed, including 51 cases of spontaneous preterm delivery (3.4%). The cervico-isthmic complex in the first trimester was significantly shorter in patients who delivered before term (43.8 mm vs 47.5 mm, p = 0.04). This difference is related to differences in length at the isthmus (10.7 mm vs 14.1 mm, p = 0.005) rather than at the cervix proper (34.5 mm vs 35.0 mm, p = 0.56).

CONCLUSIONS

Measurement of the cervico-isthmic complex enables detection of a number of patients who will go on to deliver before term. Further studies are necessary to confirm that isthmic length and not cervical length is predictive of preterm delivery.

Racial/ethnic disparities in maternal morbidities: a statewide study of labor and delivery hospitalizations in Wisconsin

We examined racial/ethnic disparities in maternal morbidities (MM) and the number of MM during labor and delivery among hospital discharges in Wisconsin. We conducted a retrospective cohort study of hospital discharge data for 206,428 pregnant women aged 13-53 years using 2005-2007 Healthcare Cost and Utilization Project State Inpatient Dataset (HCUP-SID) for Wisconsin. After adjustments for covariates, MM (preterm labor, antepartum and postpartum hemorrhage, hypertension in pregnancy, gestational diabetes, membrane-related disorders, infections and 3rd and 4th perineal lacerations) were examined using logistic regression models, and number of MM (0, 1, 2, >2 MM) were examined using multivariable ordered logistic regressions with partial proportional odds models. African-Americans had significantly higher likelihood of infections (OR = 1.74; 95% CI 1.60-1.89), preterm labor (OR = 1.42; 1.33-1.50), antepartum hemorrhage (OR = 1.63; 1.44-1.83), and hypertension complicating pregnancy (OR = 1.39; 1.31-1.48) compared to Whites. Hispanics, Asian/Pacific Islanders, and Native Americans had significantly higher likelihood of infections, postpartum hemorrhage, and gestational diabetes than Whites. Major perineal lacerations were significantly higher among Asian/Pacific Islanders (OR = 1.53; 1.34-1.75). All minority racial/ethnic groups, except Asians, had significantly higher likelihood of having 0 versus 1, 2 or >2 MM, 0 or 1 versus 2 or >2 MM, and 0, 1 or 2 versus >2 MM than white women. Findings show significant racial/ethnic disparities in MM, and suggest the need for better screening, management, and timely referral of these conditions, particularly among racial/ethnic women. Disparities in MM may be contributing to the high infant mortality and adverse birth outcomes among different racial/ethnic groups in Wisconsin.

Behavioral influences on preterm birth: integrated analysis of the pregnancy, infection, and nutrition study

Most previous studies of preterm birth have considered risk factors in isolation rather than examining the collective impact of multiple candidate determinants. In order to examine the combined impact of a set of behavioral risk factors on the risk of preterm birth, we analyzed data collected for the Pregnancy, Infection, and Nutrition Study on a range of sociodemographic, behavioral, and related factors. Women who received prenatal care at selected clinics in central North Carolina and gave birth in the period 1995-2005 were recruited into a prospective cohort study, with 4,251 women providing the required information on risk factors and pregnancy outcome. A number of demographic and behavioral attributes were modestly associated with preterm birth, with odds ratios of 1.3-1.5, including age >35, African-American ethnicity, height of 63 inches or less, parity 2+, and delivery at the academic medical center. Despite weak associations for individual risk factors, changes in a constellation of behaviors during pregnancy predict substantial shifts in the risk of preterm birth, suggesting a reduction from 8 to 3% preterm among those with a low-risk baseline profile, and a reduction from 18 to 7% preterm among those with a high-risk baseline profile. While inferences are limited by the incomplete range of available predictors, uncertainty regarding whether observed associations are causal, and substantial challenges in changing component behaviors, the possibility of substantial reduction in risk merits more serious consideration of whether behavioral interventions could markedly reduce the risk of preterm birth.

An exploratory study of the variables impacting preterm birth rates in New Mexico

Background

Preterm birth (PTB) is a substantial health problem that accounts for significant infant morbidity and mortality and poses an economic burden to both individuals and the state of residence. The goal of this study was to identify maternal risk factors for PTB in New Mexico, a poor state with a unique ethnic background, in order to identify populations at increased risk that would benefit from intervention.

Methods

This was a cross-sectional retrospective exploratory analysis of 377,770 singleton live births in the state of New Mexico from 1991-2005. Gestational age of less than 37 weeks was defined as PTB. The Kotelchuck Index was used as a measure for level of prenatal care described as inadequate, intermediate, adequate, and intensive.

Results

Of the live births analyzed, 28,036 of these were preterm (7.4%). Overall the PTB rate rose at a rate of 0.18% per year from 1991-2005. Among patients with medical risk factors, the absence of prenatal care was associated with higher odds for PTB as compared to adequate prenatal care. Other risk factors were unmarried status, education less than high school, tobacco/alcohol use, black, Asian, and white Hispanic ethnicity, and the presence of one or more medical risk factors. Statistically significant protective factors for PTB were age 25-29, education surpassing high school, and Native American race.

Conclusions

This study identified several factors that correlate with increased PTB in New Mexico, in particular ethnicity and level of prenatal care. The finding that Native American patients have a lower PTB rate compared to other groups, even though this group is traditionally one of low socioeconomic status in New Mexico, signifies that other factors yet to be identified affect PTB.

Inflammation and cardiovascular risk in women with preterm labor

BACKGROUND

Women with a history of preterm delivery have about twice the normal risk of cardiovascular disease (CVD). Mechanisms underlying this association are not well understood. The aim of the present study was to evaluate the relationships between selected metabolic CVD risk factors and markers of both systemic inflammation and endothelial dysfunction in women with spontaneous preterm labor (sPL).

METHODS

This was a case-control study in a university tertiary referral center. Forty pregnant women with sPL were compared to 50 controls during gestation. Maternal serum triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol, glycemia, insulinemia, homeostasis model assessment (HOMA), leptin, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), soluble vascular cell adhesion molecule (sVCAM), soluble intercellular adhesion molecule (sICAM), selectin, and myeloperoxidase (MPO) were measured.

RESULTS

Gestational age at study was similar in both groups (31.56±3.14 weeks of gestation vs. 31.27±2.14 weeks of gestation, p=0.62, for the control and the sPL groups, respectively). Body mass index (BMI) (21.72±2.99 vs. 23.56±3.80, p=0.01), all cholesterol fractions (HDL-C 53.44±18.22 vs. 68.32±18.38, p=0.0003; LDL-C 125.71±35.56 vs. 142.15±36.07, p=0.03, and total cholesterol 219.55±32.29 vs. 240.38±40.01, p=0.009) and MPO (3.07±0.63 vs. 3.48±0.32, p=0.0009) were significantly lower in women with sPL. Serum levels of IL-6 (0.61±0.46 vs. 0.33±0.46, p=0.007) and the ratio of total cholesterol/HDL-C (4.52±1.48 vs. 3.77±1.37, p=0.01) were significantly increased and correlated each other (r=0.21, p=0.04). Logistic regression showed that the best predictive model for sPL (R(2)=0.36, p=0.001) included BMI and total cholesterol.

CONCLUSIONS

A combination of low maternal BMI, low cholesterol levels, and high total cholesterol/HDL-C ratio is present in women with sPL and is related to inflammation.

Prevention of preterm birth

Preterm birth (delivery before 37 completed weeks of gestation) is common and rates are increasing. In the past, medical efforts focused on ameliorating the consequences of prematurity rather than preventing its occurrence. This approach resulted in improved neonatal outcomes, but it remains costly in terms of both the suffering of infants and their families and the economic burden on society. Increased understanding of the pathophysiology of preterm labor has altered the approach to this problem, with increased focus on preventive strategies. Primary prevention is a limited strategy which involves public education, smoking cessation, improved nutritional status and avoidance of late preterm births. Secondary prevention focuses on recurrent preterm birth which is the most recognisable risk factor. Widely accepted strategies include cervical cerclage, progesterone and dedicated clinics. However, more research is needed to explore the role of antibiotics and anti-inflammatory treatments in the prevention of this complex problem.

Impact of Scotland's smoke-free legislation on pregnancy complications: retrospective cohort study

BACKGROUND

Both active smoking and environmental tobacco smoke exposure are associated with pregnancy complications. In March 2006, Scotland implemented legislation prohibiting smoking in all wholly or partially enclosed public spaces. The aim of this study was to determine the impact of this legislation on preterm delivery and small for gestational age.

METHODS AND FINDINGS

We conducted logistic regression analyses using national administrative pregnancy data covering the whole of Scotland. Of the two breakpoints tested, 1 January 2006 produced a better fit than the date when the legislation came into force (26 March 2006), suggesting an anticipatory effect. Among the 716,941 eligible women who conceived between August 1995 and February 2009 and subsequently delivered a live-born, singleton infant between 24 and 44 wk gestation, the prevalence of current smoking fell from 25.4% before legislation to 18.8% after legislation (p<0.001). Three months prior to the legislation, there were significant decreases in small for gestational age (-4.52%, 95% CI -8.28, -0.60, p = 0.024), overall preterm delivery (-11.72%, 95% CI -15.87, -7.35, p<0.001), and spontaneous preterm labour (-11.35%, 95% CI -17.20, -5.09, p = 0.001). In sub-group analyses, significant reductions were observed among both current and never smokers.

CONCLUSIONS

Reductions were observed in the risk of preterm delivery and small for gestational age 3 mo prior to the introduction of legislation, although the former reversed partially following the legislation. There is growing evidence of the potential for tobacco control legislation to have a positive impact on health.

Duration of treatment for asymptomatic bacteriuria during pregnancy

BACKGROUND

A Cochrane systematic review has shown that drug treatment of asymptomatic bacteriuria in pregnant women substantially decreases the risk of pyelonephritis and reduces the risk of preterm delivery. However, it is not clear whether single-dose therapy is as effective as longer conventional antibiotic treatment.

OBJECTIVES

To assess the effects of different durations of treatment for asymptomatic bacteriuria in pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2011) and reference lists of identified articles.

SELECTION CRITERIA

Randomized and quasi-randomized trials comparing antimicrobial therapeutic regimens that differed in duration (particularly comparing single dose with longer duration regimens) in pregnant women diagnosed with asymptomatic bacteriuria.

DATA COLLECTION AND ANALYSIS

We assessed trial quality and extracted data independently.

MAIN RESULTS

We included 13 studies, involving 1622 women. All were comparisons of single-dose treatment with four- to seven-day treatments. The trials were generally of limited quality. The 'no cure rate' for asymptomatic bacteriuria in pregnant women was slightly higher for the single-dose than for the short-course treatment; however, these results were not statistically significant and showed heterogeneity. When comparing the trials that used the same antibiotic in both treatment and control groups with the trials that used different antibiotics in both groups, the 'no cure rate' risk ratio was similar. There was no statistically significant difference in the recurrence of asymptomatic bacteriuria rate between treatment and control groups. Slight differences were detected for preterm births and pyelonephritis although, apart from one trial, the sample size of the trials was inadequate. Single-dose treatment was associated with a decrease in reports of 'any side-effects' .

AUTHORS' CONCLUSIONS

Single-dose regimen of antibiotics may be less effective than the seven-day regimen. Women with asymptomatic bacteriuria in pregnancy should be treated by the standard regimen of antibiotics until more data become available testing seven-day compared with three- or five-day regimens.

Association between preterm delivery and subsequent C-reactive protein: a retrospective cohort study

OBJECTIVE

We sought to determine whether giving birth preterm is associated with raised maternal C-reactive protein (CRP) in later life and whether the association is specific to indicated or spontaneous delivery.

STUDY DESIGN

This was a Scotland-wide retrospective cohort study of 1124 women who had a first pregnancy resulting in a singleton, liveborn infant delivered between 24-43 weeks' gestation. Linear regression analysis was used to examine the association between preterm delivery and subsequent CRP concentration.

RESULTS

The difference in CRP between women who delivered term and preterm was nonsignificant on univariate analysis (beta coefficient 0.04, P = .18) but was statistically significant following adjustment for potential confounders (beta coefficient 0.05, P < .05). On subgroup analysis the association was specific to women who had had indicated preterm delivery (unadjusted beta coefficient 0.09, P < .01; adjusted beta coefficient 0.09, P < .01).

CONCLUSION

Women who undergo indicated preterm delivery are at increased risk of raised CRP in later life.

Epidemiology: the changing face of preterm birth

Preterm birth, defined as a pregnancy ending at less than 37 completed weeks of gestation, is the leading cause of infant mortality in the United States. The occurrence of preterm births rose steadily from 9.4% of all pregnancies in the United States in 1981 to 12.8% in 2006, before declining to 12.7% in 2007 and 12.3% in 2008. Most of the increase was attributable to increases in multiple gestations. Recent research has sought to understand this condition by evaluating its familial occurrence and both clinical and pathologic information to derive an etiologically homogeneous categorization.

Unemployment and pregnancy outcomes: A study within the Danish National Birth Cohort

Aims: To explore the relation between employment status, type of unemployment and pregnancy outcomes. Methods: A cohort study of 7,282 pregnancies of unemployed women and 56,014 pregnancies among women in paid jobs was performed within the Danish National Birth Cohort. Pregnancy outcomes were ascertained and information about lifestyle, occupational, medical, and obstetric factors was obtained. Logistic regression was used to calculate odds ratios (OR) for fetal loss, congenital anomalies, multiple births, sex ratio, preterm and very preterm birth and small for gestational age status, adjusting for lifestyle, medical and obstetric factors. Results: There were no differences in pregnancy outcomes between employed and unemployed women but women receiving unemployment benefit had an increased risk of preterm birth (adjusted OR (aOR) 1.16, 95% confidence interval (95% CI) 1.03—1.31) and having a small for gestational age child (aOR 1.08, 95% CI 1.00—1.19) compared with employed women. Women receiving sickness or maternity benefit had an increased risk of multiple birth (aOR 1.70, 95% CI 1.43—2.04), preterm (aOR 1.47, 95% CI 1.22—1.77) and very preterm birth (aOR 1.88, 95% CI 1.22—2.89), while those receiving an unreported type of support had an increased risk of preterm birth (aOR 1.40, 95% CI 1.02—1.93). Conclusions: We found no indication that being unemployed during pregnancy benefits or endangers the health of the child. Within the subgroups of unemployed women, we observed that women receiving unemployment and sickness or maternity benefits were at higher risk for some adverse pregnancy outcomes.

Polymorphisms in maternal and fetal genes encoding for proteins involved in extracellular matrix metabolism alter the risk for small-for-gestational-age

OBJECTIVE

To examine the association between maternal and fetal genetic variants and small-for-gestational-age (SGA).

METHODS

A case-control study was conducted in patients with SGA neonates (530 maternal and 436 fetal) and controls (599 maternal and 628 fetal); 190 candidate genes and 775 SNPs were studied. Single-locus, multi-locus and haplotype association analyses were performed on maternal and fetal data with logistic regression, multifactor dimensionality reduction (MDR) analysis, and haplotype-based association with 2 and 3 marker sliding windows, respectively. Ingenuity pathway analysis (IPA) software was used to assess pathways that associate with SGA.

RESULTS

The most significant single-locus association in maternal data was with a SNP in tissue inhibitor of metalloproteinase 2 (TIMP2) (rs2277698 OR = 1.71, 95% CI [1.26-2.32], p = 0.0006) while in the fetus it was with a SNP in fibronectin 1 isoform 3 preproprotein (FN1) (rs3796123, OR = 1.46, 95% CI [1.20-1.78], p = 0.0001). Both SNPs were adjusted for potential confounders (maternal body mass index and fetal sex). Haplotype analyses resulted in associations in α 1 type I collagen preproprotein (COL1A1, rs1007086-rs2141279-rs17639446, global p = 0.006) in mothers and FN1 (rs2304573-rs1250204-rs1250215, global p = 0.045) in fetuses. Multi-locus analyses with MDR identified a two SNP model with maternal variants collagen type V α 2 (COL5A2) and plasminogen activator urokinase (PLAU) predicting SGA outcome correctly 59% of the time (p = 0.035).

CONCLUSIONS

Genetic variants in extracellular matrix-related genes showed significant single-locus association with SGA. These data are consistent with other studies that have observed elevated circulating fibronectin concentrations in association with increased risk of SGA. The present study supports the hypothesis that DNA variants can partially explain the risk of SGA in a cohort of Hispanic women.

Maternal risk of ischaemic heart disease following elective and spontaneous pre-term delivery: retrospective cohort study of 750 350 singleton pregnancies

BACKGROUND

Previous studies have demonstrated an overall association between pre-term delivery and maternal risk of subsequent ischaemic heart disease (IHD). The underlying mechanism is unknown. We explored whether the association was specific to spontaneous or elective pre-term delivery.

METHODS

We linked three Scottish routine data sources. The Scottish Morbidity Record 1 collects data on all acute hospital admissions, Scottish Morbidity Record 2 collects data on all pregnancies and Scotland's Registrar General collates data from all death certificates. Cox proportional hazards models were used to explore associations between pre-term delivery and subsequent IHD events (fatal and non-fatal) and IHD deaths. Analysis was restricted to women aged between 35 and 65 years at either the time of their first IHD event or at the end of follow-up.

RESULTS

The cohort comprised 750,350 women who delivered a live, singleton infant following their first pregnancy. We demonstrated independent associations between pre-term delivery and IHD death [hazards ratio (HR) 2.26, 95% confidence interval (CI) 1.88-2.71] and total IHD events (HR 1.58, 95% CI 1.47-1.71). Associations were greater for elective than spontaneous pre-term delivery (P = 0.005). There was a trend whereby the association between pre-term delivery and IHD increased with decreasing age at first event.

CONCLUSIONS

We observed a stronger association between elective pre-term delivery and IHD, than spontaneous pre-term delivery and IHD. Elective pre-term delivery is usually undertaken because of growth restriction or pre-eclampsia, resulting from placental dysfunction. The age trend observed suggests an underlying genetic predisposition to both placental dysfunction and IHD.

The relationship between placental histology and cervical length in twin gestations

OBJECTIVE

To evaluate differences in placental lesions in twin pregnancies with and without mid-trimester sonographic cervical shortening.

METHODS

Two groups of women were identified: those with twin gestations and a cervical length <or=2.5 cm measured between 16 and 24 weeks of gestation and those with twin gestations and without evidence of cervical shortening. The placental pathology was then retrospectively reviewed. The placental lesions were categorized as either acute or chronic inflammatory lesions, lesions of malperfusion or coagulopathic lesions.

RESULTS

A total of 704 patients with twin gestations were identified. There was significantly more acute chorioamnionitis in patients with cervical shortening but no differences in the frequency of other placental lesions.

CONCLUSION

Placentas with acute inflammatory lesions are significantly more frequent in twin gestations with mid-trimester cervical shortening.

A case-control study of preterm delivery risk factors according to clinical subtypes and severity

AIMS

To examine risk factors of preterm delivery (PTD) among Thai women.

METHODS

Our case-control study included 467 term controls and 467 PTD cases. PTD was studied in aggregate and in subgroups (i.e. spontaneous preterm labor and delivery [SPTD], preterm premature rupture of membrane [PPROM], medically indicated preterm delivery [MIPTD], moderate preterm delivery [32-36 weeks], and very preterm delivery [<32 weeks]). We used multivariable logistic regression procedures to estimate odds ratio (OR) and 95% confidence intervals (CI) of potential PTD risk factors.

RESULTS

Advanced maternal age (>or=35 years) was associated with a 2.27-fold increased PTD risk overall (95%CI: 1.40, 3.68); and with a 3.79-fold increased risk of MIPTD (95%CI: 1.89, 7.59). Young maternal age (<20 years) was associated with a 2.07-fold increased risk of SPTD (95%CI: 1.19, 3.61). Prior history of PTD was associated with a 3.64-fold increased PTD risk overall (95%CI: 1.87, 7.09), and with a 5.69-fold increased risk of MIPTD (95%CI: 2.44, 13.24). No prenatal care was associated with all PTD subtypes. Lean women (body mass index < 18.5 kg/m(2)), compared with normal weight women (18.5-24.9 kg/m(2)), had a 1.70-fold increased risk of PTD (95%CI: 1.21, 2.39). Risk of SPTD (OR = 2.16, 95%CI: 1.44, 3.24) and very PTD (OR = 2.45, 95%CI: 1.35, 4.45) were also elevated in lean women.

CONCLUSIONS

Maternal age, pre-pregnancy body mass index, prior history of PTD and no utilization of prenatal care were covariates identified in this study as risk factors for PTD. Our findings also suggest heterogeneity in risk factors for clinical subtypes of PTD.

Epidemiology of preterm birth in Omdurman Maternity hospital, Sudan

OBJECTIVE

To investigate the prevalence and to identify risk factors for live singleton preterm birth in Omdurman Maternity hospital, Sudan.

METHODS

Case-control study. Odds ratios were adjusted for the confounding factors using multiple logistic regression models.

RESULTS

Among 3240 live birth at maternity hospital during the 3 months period of the study, 126 (3.8%) were a live preterm birth. About 99 live preterm births at a mean (SD) of 32.7 (2.2) gestational weeks were included in the final analyses. About 80 (81.0%) of these 99 preterm births were spontaneous preterm births and the rest 19 (19.0%) were medically indicated preterm births. Univariate and Multivariate analyses showed that those women who had history of miscarriage, preterm birth, cesarean delivery, dental maneuver, and vaginal bleeding in the index pregnancy, both low body mass index (BMI) (<25) and high BMI (>30) and those women who had short interpregancy interval were at higher risk for preterm birth.

CONCLUSIONS

The study showed that spontaneous preterm birth predominates in this setting. Preterm birth has a tendency to recur. Infections (periodontal) and nutrition were the risk factors for preterm birth. More research is needed especially in the area of nutrition and oral hygiene.