Odds Of Preterm Birth Research Articles

Preterm Birth (PTB) and Congenital Heart Defects (CHD): A Population-Based Study

Background and aims: PTB and CHD are the two main causes of mortality, morbidity and disability of perinatal origin. There are little population-based data on the relation between CHD and PTB. The objective of this study was to estimate the prevalence of prematurity in newborns with CHD and to study specific associations between subcategories of CHD and PTB.Methods: We used data from the EPICARD study, a population-based cohort study of CHD in France, including 2349 livebirths with CHD. We used an anatomic and clinical classification of CHD based on the International Paediatric and Congenital Cardiac Code to categorise CHD into ten groups. Data on PTB from the French National Perinatal Survey were used to compare PTB in EPICARD to that of the general population.Results: 15% (95%CI, 13.6-16.5) of the newborns with CHD were PTB and the odds of PTB was more than two fold higher than for general population (OR 2.3 95%CI, 1.8-2.8). The higher risk of PTB, and particulary very PTB (< 32 weeks), associated with CHD persisted after exclusion of cases associated with chromosomal anomalies and/or non-cardiac defects and adjustement for maternal age, sociodemographic characteristics and diabetes. There were wide variations in PTB across the ten groups examined.Conclusion: In this population-based study, the risk of PTB and particulary very PTB was substancially higher for newborn with CHD. Risk of PTB varied highly for subcategories of CHD and the specific associations oberved may be helpful for generating hypotheses about the developemental links between CHD and PTB.

Ethnic disparity in spontaneous preterm birth and maternal pre-pregnancy body mass index

To investigate differences in pre-pregnancy BMI status in patients with spontaneous preterm birth (PTB) compared with term birth and assess the role of ethnicity as a risk modifier in BMI-associated PTB. A case-control study involving self-reported African American and Caucasian women delivering singletons in Nashville, TN, USA, 2003-2009. Maternal pre-pregnancy BMI was recorded in 447 PTB-cases (African American = 145, Caucasian = 302) and 1315 term-birth controls (African American = 522; Caucasian = 793). Crude and adjusted odds ratio (OR and AOR) for PTB were calculated using normal BMI (18.5-24.9 kg/m(2)) as reference. Age, education, marital status, income, smoking, parity, previous PTB and pregnancy weight gain were included as covariates in logistic regression. No significant differences were noted in the OR for PTB among different BMI categories when women of different ethnicity were combined. Odds of PTB were greater in obese than in normal weight Caucasian women, even after adjusting for confounders (AOR = 1.84, 95%CI [1.15, 2.95]). Obese African American women had a decreased crude OR for PTB, although this was not significant after adjusting for confounders (AOR = 0.72, 95%CI [0.38, 1.40]). The odds for early PTB (<32 weeks) were decreased in obese compared with normal weight African American women (OR = 0.23, 95%CI [0.08, 0.70]), whereas they were increased in obese compared with normal weight Caucasian women (OR = 2.30, 95%CI [1.32, 4.00]). The risk for PTB in women with different pre-pregnancy BMI categories differs according to ethnicity.

Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence

Objectives To evaluate the association between thyroid autoantibodies and miscarriage and preterm birth in women with normal thyroid function. To assess the effect of treatment with levothyroxine on pregnancy outcomes...

Racial residential segregation impacts on low birth weight using improved neighborhood boundary definitions

Research on local racial residential segregation and health generally utilize census tract boundaries as a proxy from within which to estimate individual exposures. Census tracts however, may not accurately reflect the neighborhood environments in which people live and interact. Census tract geography may also capture non-exchangeable populations in socially stratified cities, impacting statistical assumptions of independence. To address these concerns, this study assessed the impact of racial residential segregation (i.e., racial isolation and racial clusters) on low birth weight (i.e., intrauterine growth retardation (IUGR) and preterm birth) in the Detroit Metropolitan Area using optimized neighborhood boundary definitions. Automated zone-matching (AZM) methodology was applied to redefine neighborhood (zones). Maternal and infant health information was obtained from Michigan’s vital statistics birth registry (n=137,965) for the years 2004–2006. Multilevel models were estimated to assess the effect of high racial isolation and high racial clusters on IUGR and preterm birth, controlling for maternal race, single marital status, smoking and area-level poverty. The results from this study showed that high racial isolation had a significant effect on IUGR, while the odds of preterm birth were higher in racially clustered zones. African American mothers were at increased odds of having IUGR or preterm infants than other mothers; however, these disparities reduced in highly segregated zones. The predicted incidence of IUGR across racially isolated zones and census tracts differed indicating a modifiable area unit problem (MAUP). MAUP effects were not observed in models predicting preterm incidence in high racial clusters or IUGR or preterm incidence in high poverty areas, demonstrating the stability-reliability of these estimates. Future research should continue to optimize neighborhood boundary definitions, while assessing the sensitivity of segregation measures to changes in scale, to improve our understanding of segregation impacts on racial disparities in low birth weight.

Parental occupation and preterm births: a nationwide epidemiological study in Sweden

The hypothesis was that some occupations could lead to preterm birth (PTB) because of potential exposures to various agents. The objective in this nationwide follow-up study was to analyse the association between PTB and parental occupational groups, controlling for potential confounders. Data from the Swedish Medical Birth Register, in which all children born in Sweden from 1990 onward are registered with their parents, were linked to census data. Inclusion criteria for the study population were employment (both women and men) and age >20 years (women). There were 816,743 first singleton live births from 1990 to 2004, of whom 43,956 were PTBs. A total of 7659 of the 43,956 PTBs were very PTBs. Odds ratios (ORs) with 95% confidence intervals were calculated separately for mothers and fathers to estimate the odds of PTB and very PTB in 51 occupational groups (reference groups: mothers or fathers who were 'Technical, science research-related workers and physicians') and by family income level. Women and men with low family incomes had increased ORs of PTB and very PTB. Significantly increased ORs of PTB (including very PTB) were found in four maternal and nine paternal occupational groups after accounting for family income, geographic region of residence, civil status, smoking habits, maternal age at infant's birth and period of birth. Further studies should examine specific agents in those parental occupations that were associated with increased odds of PTB and very PTB.

Systematic review of association between thyroid autoantibodies and adverse pregnancy outcome

BackgroundApproximately 15% of women of childbearing age have positive thyroid auto antibodies. Antibody positivity has been associated with adverse obstetric outcomes.AimTo evaluate the evidence of association between positive thyroid autoantibodies...

Neonatal Outcomes for Immigrant vs. Native-Born Mothers in Taiwan: An Epidemiological Paradox

In Taiwan, immigrant women by marriage face social discrimination due to widespread impressions that they give birth to low birth weight, high-risk, high cost babies due to their lower socioeconomic status, shorter stature, and lower pre-pregnant weight than native-born Taiwanese women. This study compared crude and adjusted birth outcomes of immigrant mothers (Chinese and Vietnamese) relative to native-born Taiwanese, and tested for the phenomenon of an epidemiological paradox of favorable neonatal outcomes among immigrants. Data from patient charts of all singleton live births during 2002-2007, weighing ≥500 and <4,000g, and ≥20weeks gestational age at a regional hospital in Kaohsiung, Taiwan, were used. Multiple regression analysis was used to test the hypothesis controlling for maternal characteristics (demographics, national origin, obstetric and prenatal factors) and neonatal characteristics (birth weight, gestational age). Of 3,267 births satisfying the inclusion criteria, 19.0% were to Chinese and Vietnamese mothers. Crude birth weight was lowest for Taiwanese mothers, who also had the highest rate of preterm delivery (<37weeks). The adjusted birth weight for Chinese and Vietnamese mothers was 87.7 and 74.7g higher, respectively than native-born Taiwanese (both P<0.001). Chinese and Vietnamese mothers also had lower odds of preterm birth (ORs 0.46 and 0.47, respectively). Findings support paradoxically better neonatal outcomes among Chinese and Vietnamese immigrant mothers in Taiwan. Findings can be used to initiate public education to reverse the widespread negative perceptions and attitudes towards immigrant spouses in Taiwan.

The effect of maternal body mass index (BMI) and oocyte source on assisted reproductive technology (ART) pregnancy rates and obstetric outcomes

OBJECTIVE: To evaluate the effect of maternal BMI and oocyte source (autologous versus donor) on ART pregnancy rates and obstetric outcomes. DESIGN: Retrospective cohort study. MATERIALS AND METHODS: The study population included 33,433 ART cycles from the SART-CORS Online database for 2007 and was limited to women with height and weight recorded and fresh transfers only. Women were categorized by their BMI as normal weight (18.5-24.9), overweight (25.0-29.9), or obese (≥30.0). Logistic regression was used to model the odds of clinical intrauterine gestation as the treatment outcome, live birth as the pregnancy outcome, and preterm (<37 weeks) for singleton live births or early preterm (<33 weeks) for multiple live births, as adjusted odds ratios (AOR) and 95% confidence intervals, with autologous oocyte use as the reference group. Models were adjusted for maternal age, race and ethnicity, smoking, number of embryos transferred, and infertility diagnoses. Among live births, models of prematurity were additionally adjusted for number of fetal heartbeats on early ultrasound. RESULTS: Regardless of BMI group, women using donor oocytes were significantly older, more likely to be diagnosed with diminished ovarian reserve or male factor infertility, and were less likely to smoke, although smoking rates paralleled increasing BMI. With the use of donor oocytes, the odds of pregnancy (AORs 4.41, 4.72, and 4.75, respectively) and a live birth (AORs 2.32, 3.12, and 2.27, respectively) were significantly increased for all three BMI groups. The magnitude of the increase was strikingly similar across all three BMI groups. The odds of preterm birth among singletons and early preterm birth among multiples were not significantly affected by oocyte source for any of the BMI groups. CONCLUSIONS: The use of donor oocytes significantly increases the chances of achieving a pregnancy and a live birth outcome, even in the presence of increasing maternal obesity.

Chlamydia trachomatis infection during pregnancy and the risk of preterm birth: a case-control study

Our goal was to define the risks of preterm birth associated with Chlamydia trachomatis (CT) and other sexually transmitted infections (STIs) among pregnant women. We accessed clinical records from July 2005 to February 2008. The study population included all pregnant women who gave birth to a singleton newborn of at least 20 weeks' gestation, and who had antenatal care information. We estimated the impact of CT and other STI on the odds of preterm birth using logistic regression. Overall, 2127 women were included in this analysis. The prevalence of CT infection was 4.7%. CT diagnosis was not associated with preterm birth. In conclusion, this study did not find an association between CT and preterm birth. The lack of an association may be explained by early treatment. Future studies evaluating the timing of screening for STIs may help clarify whether pregnant women would benefit more from earlier screening.

Intention to Become Pregnant and Low Birth Weight and Preterm Birth: a Systematic Review

Increased stress, psychosocial problems, economic disadvantages, and lack of prenatal care are proposed to explain discrepancies in the outcome of unintended pregnancies. Studies of maternal intention and pregnancy outcomes have yielded varied results. Objective is to review studies of the risk of low birth weight (LBW)/preterm births (PTB) associated with unintended pregnancies ending in a live birth. We reviewed studies reporting on maternal intentions and outcomes from Medline, Embase, CINAHL, and bibliographies of identified articles. An unintended pregnancy was further classified as mistimed (not intended at that time) or unwanted (not desired at any time). Studies reporting an association between pregnancy intention and any of the outcomes were included. Study quality was assessed for biases in selection, exposure assessment, confounder adjustment, analyses, outcomes assessment, and attrition. Unadjusted and adjusted data from included studies were extracted by two reviewers. There were significantly increased odds of LBW among unintended pregnancies [odds ratio (OR) 1.36, 95% confidence interval (CI) 1.25, 1.48] ending in a live birth. Within the unintended category, mistimed (OR 1.31, 95% CI 1.13, 1.52) and unwanted (OR 1.51, 95% CI 1.29, 1.78) pregnancies were associated with LBW. There were statistically significantly increased odds of PTB among unintended (OR 1.31, 95% CI 1.09, 1.58), and unwanted (OR 1.50, 95% CI 1.41, 1.61) but not for mistimed (OR 1.36, 95% CI 0.96, 1.93) pregnancies. Unintended, unwanted, and mistimed pregnancies ending in a live birth are associated with a significantly increased risk of LBW and PTB.

Racial and ethnic disparities in assisted reproductive technology outcomes in the United States

To evaluate ethnic differences in assisted reproductive technology (ART) outcomes in the United States. Historical cohort study. Clinic-based data. A total of 139,027 ART cycles from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System online database for 2004-2006, limited to white, Asian, black, and Hispanic women. None. Logistic regression was used to model the odds of pregnancy and live birth; among singletons and twins, the odds of preterm birth and fetal growth restriction. Results are presented as adjusted odds ratios, with white women as the reference group. The odds of pregnancy were reduced for Asians (0.86), and the odds of live birth were reduced for all groups: Asian (0.90), black (0.62), and Hispanic (0.87) women. Among singletons, moderate and severe growth restriction were increased for all infants in all three minority groups (Asians [1.78, 2.05]; blacks [1.81, 2.17]; Hispanics [1.36, 1.64]), and preterm birth was increased among black (1.79) and Hispanic women (1.22). Among twins, the odds for moderate growth restriction were increased for infants of Asian (1.30) and black women (1.97), and severe growth restriction was increased among black women (3.21). The odds of preterm birth were increased for blacks (1.64) and decreased for Asians (0.70). There are significant disparities in ART outcomes according to ethnicity.

An Investigation of Paternity Status and Other Factors Associated with Racial and Ethnic Disparities in Birth Outcomes in Milwaukee, Wisconsin

To examine factors associated with preterm birth and low birthweight and the role of paternity status in birth outcomes among racial/ethnic groups in Milwaukee. Retrospective analysis of data on 151,869 singleton live births (1993-2006) from the City of Milwaukee, Wisconsin. Multivariate logistic regression models were used to examine demographic and medical factors associated with racial/ethnic disparities in preterm birth and low birthweight. African-Americans, whites, Hispanics, and women of "other" racial groups accounted for 46%, 33%, 16%, and 5% of births, respectively. Preterm birth and low birthweight rates were three times greater for African-American women compared to whites. Compared to white women, the odds of preterm birth were 82% and 35% greater for African-American and other minority women, respectively. All minority women had greater adjusted odds of low birthweight than whites, with African-American women at greatest risk (OR 2.36:2.23-2.49). Across racial/ethnic groups, significant predictors of both outcomes included being unmarried with no child's father on record, maternal smoking, chronic hypertension, previous preterm birth, and inadequate and adequate plus prenatal care. Paternity status had a gradient effect for whites and Hispanics with unmarried women with no child's father's name on record at greatest risk, followed by those with court-established paternity and those with paternity statement at lowest risk for both outcomes. Implementing policies/programs that promote smoking cessation, proper management of maternal conditions, targeted interventions for women with previous preterm birth, and paternal involvement have the potential to reduce disparities in birth outcomes.

Neighbourhood socioeconomic status, maternal education and adverse birth outcomes among mothers living near highways

Background:Residential proximity to highways is a potential proxy for exposure to traffic-related pollution that has been linked to adverse birth outcomes. We evaluated whether proximity to highway interacts with individual...

Ambient Air Pollution and Preterm Birth in the Environment and Pregnancy Outcomes Study at the University of California, Los Angeles

The authors conducted a case-control survey nested within a birth cohort and collected detailed risk factor information to assess the extent to which residual confounding and exposure misclassification may impact air pollution effect estimates. Using a survey of 2,543 of 6,374 women sampled from a cohort of 58,316 eligible births in 2003 in Los Angeles County, California, the authors estimated with logistic regression and two-phase models the effects of pregnancy period-specific air pollution exposure on the odds of preterm birth. For the first trimester, the odds of preterm birth consistently increased with increasing carbon monoxide exposures and also at high levels of exposure to particulate matter less than or equal to 2.5 microm in diameter (>21.4 microg/m(3)), regardless of type of data (cohort/sample) or covariate adjustment (carbon monoxide exposures of >1.25 ppm increased the odds by 21-25%). Women exposed to carbon monoxide above 0.91 ppm during the last 6 weeks of pregnancy experienced increased odds of preterm birth. Crude and birth certificate covariate-adjusted results for carbon monoxide differed from each other. However, further adjustment for risk factors assessed in the survey did not change effect estimates for short-term pollutant averages appreciably, except for time-activity patterns, which strengthened the observed associations. These results confirm the importance of reducing exposure misclassification when evaluating the effect of traffic-related pollutants that vary spatially.

The impact of maternal BMI, parity and GA on the comparative efficacy of transcervical foley catheter with or without an extraamniotic saline infusion for cervical ripening and labor induction in women with an unfavorable cervix

TERM BIRTH MICHAEL RUMA, AMY HERRING, CAROLYN SALAFIA, JOHN THORP, University of North Carolina at Chapel Hill, Obstetrics & Gynecology, Chapel Hill, North Carolina, University of North Carolina at Chapel Hill, Biostatistics, Chapel Hill, North Carolina, Columbia University Mailman School of Public Health, Epidemiology, New York, New York OBJECTIVE: To assess the relationship between uteroplacental vascular histopathology and preterm birth (PTB). STUDY DESIGN: Placentas from the prospective Pregnancy, Infection, and Nutrition study were evaluated by gross and microscopic examination by a single perinatal pathologist. Presence of uteroplacental vascular pathology, such as syncytial knots, vascular fibrosis, and thrombi were quantified. PTB was defined as delivery !37 weeks; extreme PTB was defined as !32 weeks. The relationship between uteroplacental vascular pathology and PTB was determined by Fisher’s exact or Chi-square tests. Odds ratios (OR, 95% CI) for PTB stratified by gestational age at delivery were calculated. RESULTS: Placentas from 154 PTB (78 spontaneous and 76 medically indicated) and 843 term births were analyzed. There were 21 extreme PTB. 69 (45%) of 154 PTB and 19 (90%) of extreme PTB had uteroplacental vascular pathology. Uteroplacental vascular pathology was more common among spontaneous versus medically indicated PTB (53 vs. 37%, p=.05). Uteroplacental vascular pathology was more common in extreme PTB, compared to 32-37 week PTB, and term birth (90 vs. 38, and vs. 28% respectively, p!.0001). The odds for PTB were higher among women with uteroplacental vascular pathology (Table). CONCLUSION: Uteroplacental vascular pathology is more common among PTB and extreme PTB. Understanding the etiology of uteroplacental vascular pathology may lead to a novel approach to PTB prevention.

Maternal Hypertension and Spontaneous Preterm Births Among Black Women

Objective: To examine effects of maternal hypertension on spontaneous preterm birth (birth at less than 37 weeks’ gestation) among black women. Methods: Using hospital discharge summary records from the National Hospital Discharge Survey between 1988 and 1993, we conducted a case-control study to assess the risk of spontaneous preterm birth among black women with chronic hypertension preceding pregnancy and pregnancy-induced hypertension. Logistic regression was used to derive odds ratios (ORs) and 95% confidence intervals (CIs). Results: Preterm births were almost two times more likely for women with pregnancy-induced hypertension (OR = 1.8; 95% CI, 1.5, 2.2), more than 1.5 times more likely for women with chronic hypertension preceding pregnancy (OR = 1.6; 95% CI, 1.3, 2.1), and more than four times more likely for women with pregnancy-aggravated hypertension (OR = 4.4; 95% CI, 2.9, 6.7) compared with normotensive women. Preterm births also were associated significantly with antepartum hemorrhage, poor fetal growth, marital status, and source of payment. The odds of preterm birth by maternal hypertension were increased among women with chronic hypertension and genitourinary infection, whereas the odds of preterm birth were reduced among women with pregnancy-induced hypertension and genitourinary infection. Conclusion: These findings are important in demonstrating the relation between type of hypertension in pregnancy and preterm birth. The relationships between maternal hypertension and preterm birth need to be further investigated to provide some guidelines in the management of hypertension in pregnancy and assessment of prenatal care compliance for black women, particularly when genitourinary infection is present.