Investigating socio-economic disparities in preterm birth: evidence for selective study participation and selection bias

Negative emotionality as a candidate mediating mechanism linking prenatal maternal mood problems and offspring internalizing behaviour

Negative emotionality (NE) was evaluated as a candidate mechanism linking prenatal maternal affective symptoms and offspring internalizing problems during the preschool/early school age period. The participants were 335 mother-infant dyads from the Maternal Adversity, Vulnerability and Neurodevelopment project. A Confirmatory Bifactor Analysis (CFA) based on self-report measures of prenatal depression and pregnancy-specific anxiety generated a general factor representing overlapping symptoms of prenatal maternal psychopathology and four distinct symptom factors representing pregnancy-specific anxiety, negative affect, anhedonia and somatization. NE was rated by the mother at 18 and 36 months. CFA based on measures of father, mother, child-rated measures and a semistructured interview generated a general internalizing factor representing overlapping symptoms of child internalizing psychopathology accounting for the unique contribution of each informant. Path analyses revealed significant relationships among the general maternal affective psychopathology, the pregnancy- specific anxiety, and the child internalizing factors. Child NE mediated only the relationship between pregnancy-specific anxiety and the child internalizing factors. We highlighted the conditions in which prenatal maternal affective symptoms predicts child internalizing problems emerging early in development, including consideration of different mechanistic pathways for different maternal prenatal symptom presentations and child temperament.

Happy prenatal relationships, healthy postpartum mothers: a prospective study of relationship satisfaction, postpartum stress, and health

OBJECTIVE

Major life transitions, such as the arrival of a new baby, can be stressful, and therefore, costly to one's health. Being in a satisfying romantic relationship has been previously linked with better health, perhaps because it provides access to a bank of psychosocial resources. The objective of the present research was two-fold. First, we examined whether prenatal relationship satisfaction benefitted mothers' postpartum health. Second, we examined whether this association was mediated by reduced postpartum stress. Design: Pregnant women (N = 431) were drawn from a larger prospective pregnancy and birth cohort study. Main Outcome Measures: Participants reported on their relationship satisfaction, perceived stress, and perceived health at two time points: 24-26 weeks of gestation and 6 months postpartum. Results: Greater prenatal romantic satisfaction predicted enhanced perceived postpartum health, and reduced perceived postpartum stress appeared to mediate this link. Conclusion: This research demonstrates that greater prenatal relationship satisfaction is associated with better postpartum health and provides evidence for one potential mechanism for this link: the reduction of perceived postpartum stress. Thus, assessments of women's prenatal relationship satisfaction may help identify those who are at higher risk of experiencing poor postpartum health. Implications for interventions are discussed.

Conducting a study to assess the long-term impacts of injury after 9/11: participation, recall, and description

Background

The World Trade Center (WTC) attacks on September 11, 2001 (9/11) resulted in over 2700 fatalities and thousands injured. Injury on 9/11 has been identified as a risk factor for physical and mental health conditions, but the reasons for this are not well understood. In a population exposed to 9/11 and since followed, an in-depth study on the impacts of injury on 9/11 was conducted to identify factors that contribute to long-term functional issues. This report sought to examine factors influencing participation, participant recall of injury status over time, and determinants of injury severity.

Methods

Enrollees from the World Trade Center Health Registry who completed all surveys between 2003 and 2016 and initially reported being injured (N = 2699) as well as a sample of non-injured (N = 2598) were considered to be eligible for the Health and Quality of Life 15 Years after 9/11 (HQoL) Study. Predictors of study non-participation and inconsistent recall of injury over time (i.e., discrepant reports) were identified through fitting log binomial models.

Results

Participation rates were high overall (76.1%) and did not vary by initially reported injury status, although younger (vs. older), non-White (vs. White), and less educated (vs. more educated) enrollees were less likely to participate in the HQoL Study. Discrepant reporting of 9/11 injury status was much more common among enrollees who initially reported being injured on 9/11 (49.6%) compared with those who did not (7.3%). However, those who incurred more severe injuries on 9/11 were less likely to have discrepant reporting over time compared with those with more minor injuries (broken bone vs. sprain: risk ratio = 0.33, 95% Confidence Interval: 0.19, 0.57). Among those who consistently reported that they were injured on 9/11, most injuries occurred as a result of descending down stairs (31.5%) or by tripping and falling (19.9%); although being hit by a falling object was most often associated with high severity injuries (63.2%) compared with other modes of injury.

Conclusions

These findings highlight the methodological issues involved in conducting a study on the long-term impact of injury more than a decade after the initial incident and may be relevant to future investigators. Factors affecting participation rates, such as demographic characteristics, and those related to discrepant reporting over time, such as injury severity, may affect both the internal and external validity of studies examining the long-term impact of injury.

Cervical pathways for racial disparities in preterm births: the Preterm Prediction Study

Purpose: Racial disparities in preterm birth have been long recognized, but the social and biological mechanisms for these differences are unclear. Our analysis had three goals: (1) to determine the relation between race and other social risk factors and cervical structure; (2) to determine whether social factors mediate the relation between race and cervical structure; and (3) to determine whether racial disparities in preterm birth (PTB) are mediated through changes in cervical structure observed earlier in pregnancy. Materials and methods: Data from the Maternal Fetal Medicine Unit network Preterm Prediction Study were used to examine the relation between race and other social factors and cervical properties throughout pregnancy in 2920 black and white women. Outcomes included cervical length and dilation; cervical score (cervical length-internal dilation); and whether membranes protruded at 22-24 and 26-29 weeks. Race, education, income, insurance type, and marital status were examined as predictors of the outcomes using linear and logistic regression, adjusting for age, BMI, parity, and smoking. Mediation analysis was used to examine whether (a) any social factors explained racial differences in cervical properties, and (b) whether cervical properties mediated racial differences in risk for preterm birth. Results: Shorter cervical length, especially at a subject's first visit, was associated with black race (adjusted beta -1.56 mm, p < .01) and lower income (adjusted beta -1.48, p =.05). External dilation was not associated with social factors, while internal dilation was associated with black race and lower education. Black race and marital status were associated with lower cervical score. There was no evidence of mediation of the racial effect on cervical properties by any social factor. Shorter cervical length, dilation, and score were all associated with preterm birth (p < .01). Mediation analysis indicated that each of these mediated the effect of race, but explained a small proportion of the total effect (15-25%). Conclusions: Race, and, to a lesser extent, other social factors are correlated with adverse cervical properties. This pathway could explain a proportion of the racial disparity in preterm birth.

Evidence of a gene-environment interaction of NODAL variants and inflammation in preterm birth

OBJECTIVE

NODAL has been implicated in timing of parturition and immune regulation. We investigated the relationship between NODAL polymorphisms, infection/inflammation, and preterm birth.

STUDY DESIGN

For this secondary analysis, 613 women (189 preterm and 424 term) from the Montreal Prematurity Study were genotyped for NODAL polymorphisms and assessed for bacterial vaginosis and placental inflammation.

RESULT

NODAL polymorphisms were not associated with preterm birth. However, the rs2231947(C>T) variant allele was associated with increased risk for preterm birth among women with bacterial vaginosis (odds ratio: 2.76, 95% confidence interval: 1.12-6.85). Among women without placental inflammation, the rs1904589(A>G) variant allele was associated with increased risk of preterm birth (odds ratio: 1.31, 95% confidence interval: 1.02-1.70). Among women with placental inflammation, the rs10999338(C>T) variant allele was associated with reduced risk of preterm birth (odds ratio: 0.50, 95% confidence interval: 0.29-0.87).

CONCLUSION

The effect of NODAL polymorphisms on preterm birth depends on maternal infection/inflammation status.

Cumulative prenatal exposure to adversity reveals associations with a broad range of neurodevelopmental outcomes that are moderated by a novel, biologically informed polygenetic score based on the serotonin transporter solute carrier family C6, member 4 (SLC6A4) gene expression

While many studies focus on the association between early life adversity and the later risk for psychopathology, few simultaneously explore diverse forms of environmental adversity. Moreover, those studies that examined the cumulative impact of early life adversity focus uniquely on postnatal influences. The objective of this study was to focus on the fetal period of development to construct and validate a cumulative prenatal adversity score in relation to a wide range of neurodevelopmental outcomes. We also examined the interaction of this adversity score with a biologically informed genetic score based on the serotonin transporter gene. Prenatal adversities were computed in two community birth cohorts using information on health during pregnancy, birth weight, gestational age, income, domestic violence/sexual abuse, marital strain, as well as maternal smoking, anxiety, and depression. A genetic score based on genes coexpressed with the serotonin transporter in the amygdala, hippocampus, and prefrontal cortex during prenatal life was constructed with an emphasis on functionally relevant single nucleotide polymorphisms, that is, expression quantitative trait loci. Prenatal adversities predicted a wide range of developmental and behavioral alterations in children as young as 2 years of age in both cohorts. There were interactions between the genetic score and adversities for several domains of the Child Behavior Checklist (CBCL), with pervasive developmental problems remaining significant adjustment for multiple comparisons. Scores combining different prenatal adverse exposures predict childhood behavior and interact with the genetic background to influence the risk for psychopathology.

Generalisability of vaccine effectiveness estimates: an analysis of cases included in a postlicensure evaluation of 13-valent pneumococcal conjugate vaccine in the USA

OBJECTIVES

External validity, or generalisability, is the measure of how well results from a study pertain to individuals in the target population. We assessed generalisability, with respect to socioeconomic status, of estimates from a matched case-control study of 13-valent pneumococcal conjugate vaccine effectiveness for the prevention of invasive pneumococcal disease in children in the USA.

DESIGN

Matched case-control study.

SETTING

Thirteen active surveillance sites for invasive pneumococcal disease in the USA.

PARTICIPANTS

Cases were identified from active surveillance and controls were age and zip code matched.

OUTCOME MEASURES

Socioeconomic status was assessed at the individual level via parent interview (for enrolled individuals only) and birth certificate data (for both enrolled and unenrolled individuals) and at the neighbourhood level by geocoding to the census tract (for both enrolled and unenrolled individuals). Prediction models were used to determine if socioeconomic status was associated with enrolment.

RESULTS

We enrolled 54.6% of 1211 eligible cases and found a trend toward enrolled cases being more affluent than unenrolled cases. Enrolled cases were slightly more likely to have private insurance at birth (p=0.08) and have mothers with at least some college education (p<0.01). Enrolled cases also tended to come from more affluent census tracts. Despite these differences, our best predictive model for enrolment yielded a concordance statistic of only 0.703, indicating mediocre predictive value. Variables retained in the final model were assessed for effect measure modification, and none were found to be significant modifiers of vaccine effectiveness.

CONCLUSIONS

We conclude that although enrolled cases are somewhat more affluent than unenrolled cases, our estimates are externally valid with respect to socioeconomic status. Our analysis provides evidence that this study design can yield valid estimates and the assessing generalisability of observational data is feasible, even when unenrolled individuals cannot be contacted.

Home visitation programs: an untapped opportunity for the delivery of early childhood obesity prevention

BACKGROUND

Extant obesity efforts have had limited impact among low-income underserved children, in part because of limitations inherent to existing programs: (i) short duration and low intensity; (ii) late timing of implementation, when children are already overweight or obese; (iii) intervention delivery limiting their accessibility and sustainability; and (iv) failure to address barriers such as a lack of culturally competent services, poverty and housing instability, which interfere with healthy lifestyle changes.

OBJECTIVE

This concept paper proposes an innovative model of obesity prevention implemented in infancy and sustained throughout early childhood to address the limitations of current obesity prevention efforts. Specifically, we propose to integrate sustained, weekly, in-home obesity prevention as part of the services already delivered by ongoing Home Visitation Programs, which currently do not target obesity prevention.

CONCLUSION

The home visiting structure represents an ideal model for impactful obesity prevention as home visitation programs: (i) already provide comprehensive services to diverse low-income infants and families who are most at risk for obesity and poor health because of socio-economic and structural conditions; (ii) services are initiated in infancy and sustained throughout critical developmental periods for the formation of healthy/unhealthy behaviors; and (iii) have been in place for more than 40 years, with a widespread presence across the United States and nationwide, which is critical for the scalability and sustainability of obesity prevention.

Bias with respect to socioeconomic status: A closer look at zip code matching in a pneumococcal vaccine effectiveness study

In 2010, 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in the US for prevention of invasive pneumococcal disease in children. Individual-level socioeconomic status (SES) is a potential confounder of the estimated effectiveness of PCV13 and is often controlled for in observational studies using zip code as a proxy. We assessed the utility of zip code matching for control of SES in a post-licensure evaluation of the effectiveness of PCV13 (calculated as [1-matched odds ratio]*100). We used a directed acyclic graph to identify subsets of confounders and collected SES variables from birth certificates, geocoding, a parent interview, and follow-up with medical providers. Cases tended to be more affluent than eligible controls (for example, 48.3% of cases had private insurance vs. 44.6% of eligible controls), but less affluent than enrolled controls (52.9% of whom had private insurance). Control of confounding subsets, however, did not result in a meaningful change in estimated vaccine effectiveness (original estimate: 85.1%, 95% CI 74.8–91.9%; adjusted estimate: 82.5%, 95% CI 65.6–91.1%). In the context of a post-licensure vaccine effectiveness study, zip code appears to be an adequate, though not perfect, proxy for individual SES.

•

Socioeconomic status (SES) may impact enrollment in vaccine effectiveness studies.

•

We assessed zip code matching as a proxy for SES in a pneumococcal vaccine study.

•

After zip code matching, we found differences in SES between cases and controls.

•

Differences did not appear to substantially bias estimated vaccine effectiveness.

Association between Exposure to Endocrine Disruptors in Drinking Water and Preterm Birth, Taking Neighborhood Deprivation into Account: A Historic Cohort Study

Background: The relationship between preterm birth (PTB) and endocrine disruptor exposure in drinking-water has only occasionally been studied. The objective of this work was to investigate the relation between exposure to atrazine metabolites, or atrazine/nitrate mixtures, in drinking-water during pregnancy and prevalence of PTB neonates, while taking neighborhood deprivation into account. Method: A historic cohort study in Deux-Sèvres, France, between 2005 and 2010 with a multiple imputation model for data of exposure to atrazine metabolites and a logistic regression were carried out. Results: We included 13,654 mother/neonate pairs living in 279 different census districts. The prevalence of PTB was 4%. Average atrazine metabolite concentration was 0.019 ± 0.009 (0.014–0.080) µg/L and 39% of mothers lived in less deprived areas. The individual data were associated with risk of PTB. The risk of PTB when exposed to highest concentration of atrazine metabolite adjusted for confounders, was ORa 1.625 95% CI [0.975; 2.710]. Taking, or not, neighborhood deprivation into account did not change the result. Exposure to atrazine/nitrate mixtures remained non-significant. Conclusions: Even if we took neighborhood deprivation into account, we could not show a significant relationship between exposure to atrazine metabolites, or mixtures, in drinking-water during the second trimester of pregnancy and PTB.

Prenatal maternal depression and child serotonin transporter linked polymorphic region (5-HTTLPR) and dopamine receptor D4 (DRD4) genotype predict negative emotionality from 3 to 36 months

Prenatal maternal depression and a multilocus genetic profile of two susceptibility genes implicated in the stress response were examined in an interaction model predicting negative emotionality in the first 3 years. In 179 mother-infant dyads from the Maternal Adversity, Vulnerability, and Neurodevelopment cohort, prenatal depression (Center for Epidemiologic Studies Depressions Scale) was assessed at 24 to 36 weeks. The multilocus genetic profile score consisted of the number of susceptibility alleles from the serotonin transporter linked polymorphic region gene (5-HTTLPR): no long-rs25531(A) (LA: short/short, short/long-rs25531(G) [LG], or LG/LG] vs. any LA) and the dopamine receptor D4 gene (six to eight repeats vs. two to five repeats). Negative emotionality was extracted from the Infant Behaviour Questionnaire-Revised at 3 and 6 months and the Early Child Behavior Questionnaire at 18 and 36 months. Mixed and confirmatory regression analyses indicated that prenatal depression and the multilocus genetic profile interacted to predict negative emotionality from 3 to 36 months. The results were characterized by a differential susceptibility model at 3 and 6 months and by a diathesis-stress model at 36 months.

Neighborhood deprivation and maternal psychological distress during pregnancy: a multilevel analysis

Maternal psychosocial distress is conceptualized as an important factor underlying the association between neighborhood deprivation and pregnancy outcomes. However, empirical studies to examine effects of neighborhood deprivation on psychosocial distress during pregnancy are scant. Based on a large multicenter cohort of pregnant women in Montreal, we examined (1) the extent to which psychosocial distress is clustered at the neighborhood-level, (2) the extent to which the clustering is explained by neighborhood material or social deprivation, and (3) whether associations between neighborhood deprivation and psychosocial distress persist after accounting for neighborhood composition (individual-level characteristics) using multilevel analyses. For 5,218 women residing in 740 neighborhoods, a prenatal interview at 24-26 gestational weeks measured both general and pregnancy-related psychological distress using well-validated scales: perceived stress, social support, depressive symptoms, optimism, commitment to the pregnancy, pregnancy-related anxiety, and maternal locus-of-control. Neighborhood deprivation indices were linked to study participants by their residential postal code. Neighborhood-level clustering (intraclass correlation) ranged from 1 to 2 % for perceived stress (lowest), optimism, pregnancy-related anxiety, and commitment to pregnancy to 4-6 % for perceived social support, depressive symptoms, and maternal locus of control (highest). Neighborhood material deprivation explained far more of the clustering (23-75 %) than did social deprivation (no more than 4 %). Although both material and social deprivation were associated with psychological distress in unadjusted analyses, the associations disappeared after accounting for individual-level socioeconomic characteristics. Our results highlight the importance of accounting for individual-level socioeconomic characteristics in studies of potential neighborhood effects on maternal mental health.

The impact of postpartum contraception on reducing preterm birth: findings from California

OBJECTIVE

Family planning is recommended as a strategy to prevent adverse birth outcomes. The potential contribution of postpartum contraceptive coverage to reducing rates of preterm birth is unknown. In this study, we examine the impact of contraceptive coverage and use within 18 months of a birth on preventing preterm birth in a Californian cohort.

STUDY DESIGN

We identified records for second or higher-order births among women from California's 2011 Birth Statistical Master File and their prior births from earlier Birth Statistical Master Files. To identify women who received contraceptive services from publicly funded programs, we applied a probabilistic linking methodology to match birth files with enrollment records for women with Medi-Cal or Family Planning, Access, Care, and Treatment Program (PACT) claims. The length of contraceptive coverage was determined through applying an algorithm based on the specified method and the quantity dispensed. Preterm birth was defined as a birth occurring <37 weeks' gestation, and calculated from the medical record. We further examined differences in preterm birth using subcategories defined by the World Health Organization: extremely preterm (<28 weeks); very preterm (28 to <32 weeks); and moderate to late preterm (32 to <37 weeks). We built a multivariable regression model to examine the effect of contraceptive coverage on the odds of a preterm birth and control for key covariates.

RESULTS

The cohort consisted of 111,948 women who were seen at least once by a Medi-Cal or Family PACT provider within 18 months of delivery. Of the cohort, 9.75% had a preterm birth. Contraceptive coverage was found to be protective against preterm birth. For every month of contraceptive coverage, odds of a preterm birth <37 weeks decrease by 1.1% (odds ratio, 0.989; 95% confidence interval, 0.986-0.993).

CONCLUSION

Improving postpartum contraceptive use has the potential to reduce preterm births.

Associations between late and moderately preterm birth and smoking, alcohol, drug use and diet: a population-based case-cohort study

OBJECTIVE

This study explores the associations between lifestyle factors and late and moderate preterm birth (LMPT: 32(+0)-36(+6) weeks' gestation), a relatively under-researched group.

STUDY DESIGN

A population-based case-cohort study was undertaken involving 922 LMPT and 965 term (37+ weeks' gestation) singleton live and stillbirths born between 1 September 2009 and 31 December 2010 to women residing in Leicestershire and Nottinghamshire, UK. Poisson multivariable regression models were fitted to estimate relative risks (RR) of LMPT birth associated with maternal smoking, alcohol and recreational drug use, and diet.

RESULTS

Women who smoked during pregnancy were at 38% increased risk of LMPT birth compared with non-smokers (RR 1.38, 95% CI (1.04 to 1.84)). Low consumption of fruit and vegetables was associated with a 31% increased risk compared with those who reported eating higher consumption levels (RR 1.31 (1.03 to 1.66)). Women who did not have any aspects of a Mediterranean diet were nearly twice as likely to deliver LMPT compared with those whose diet included more Mediterranean characteristics (RR 1.81 (1.04 to 3.14)). Women who smoked and consumed low levels of fruit and vegetables (5% of women) were at particularly high risk (RR=1.81 (1.29 to 2.55)). There was no significant effect of alcohol or recreational drug use on LMPT birth.

CONCLUSIONS

Smoking and poor diet during pregnancy, factors that strongly impact on very preterm birth, are also important at later gestations and experienced together are associated with an elevated rate of risk. Our findings suggest early cessation of smoking during pregnancy may be an effective strategy to reduce LMPT births.

A randomised controlled trial comparing opt-in and opt-out home visits for tracing lost participants in a prospective birth cohort study

BACKGROUND

Attrition is an important problem in cohort studies. Tracing cohort members who have moved or otherwise lost contact with the study is vital. There is some debate about the acceptability and relative effectiveness of opt-in versus opt-out methods of contacting cohort members to re-engage them in this context. We conducted a randomised controlled trial to compare the two approaches in terms of effectiveness (tracing to confirm address and consenting to continue in the study), cost-effectiveness and acceptability.

METHODS

Participants in this trial were individuals (young people and mothers) recruited to the Avon Longitudinal Study of Parents and Children (ALSPAC), who had not engaged with the study in the previous 5 years and for whom mail had been returned from their last known address. The sampling frame was restricted to those for whom database searching led to a potential new address being found in the Bristol area. 300 participants were randomly selected and assigned using stratified randomisation to the opt-in or opt-out arm. A tailored letter was sent to the potential new address, either asking participants to opt in to a home visit, or giving them the option to opt out of a home visit. Fieldworkers from Ipsos MORI conducted home visits to confirm address details.

RESULTS

The proportion who were traced was higher in the opt-out arm (77/150 = 51 %) than the opt-in arm (6/150 = 4 %), as was the proportion who consented to continue in ALSPAC (46/150 = 31 % v 4/150 = 3 %). The mean cost per participant was £8.14 in the opt-in arm and £71.93 in the opt-out arm. There was no evidence of a difference in acceptability between the opt-in and opt-out approaches.

CONCLUSION

Since the opt-in approach yielded very low response rates, and there were no differences in terms of acceptability, we conclude that the opt-out approach is the most effective method of tracing disengaged study members. The gains made in contacting participants must be weighed against the increase in cost using this methodology.

Do the causes of infertility play a direct role in the aetiology of preterm birth?

BACKGROUND

It is well established that singletons born of assisted reproductive technology are at higher risk of preterm birth and other adverse outcomes. What remains unclear is whether the increased risk is attributable to the effects of the treatment alone or whether the underlying causes of infertility also play a role. The aim of this study was to examine whether any of the six categories of causes of infertility were associated with a direct effect on preterm birth using causal mediation analysis.

METHODS

We assembled a hospital-based cohort of births delivered at a large tertiary care hospital in Montreal, Canada between 2001 and 2007. Causes of infertility were ascertained through a clinical database and medical chart abstraction. We employed marginal structural models (MSM) to estimate the controlled direct effect of each cause of infertility on preterm birth compared with couples without the cause under examination.

RESULTS

The final study cohort comprised 18,598 singleton and twin pregnancies, including 1689 in couples with ascertained infertility. MSM results suggested no significant direct effect for any of the six categories of causes. However, power was limited in smaller subgroup analyses, and a possible direct effect for uterine abnormalities (e.g. fibroids and malformations) could not be ruled out.

CONCLUSION

In this cohort, most of the increased risk of preterm birth appeared to be explained by maternal characteristics (such as age, body mass index, and education) and by assisted reproduction. If these findings are corroborated, physicians should consider these risks when counselling patients.

Infants born late/moderately preterm are at increased risk for a positive autism screen at 2 years of age

OBJECTIVES

To assess the prevalence of positive screens using the Modified Checklist for Autism in Toddlers (M-CHAT) questionnaire and follow-up interview in late and moderately preterm (LMPT; 32-36 weeks) infants and term-born controls.

STUDY DESIGN

Population-based prospective cohort study of 1130 LMPT and 1255 term-born infants. Parents completed the M-CHAT questionnaire at 2-years corrected age. Parents of infants with positive questionnaire screens were followed up with a telephone interview to clarify failed items. The M-CHAT questionnaire was re-scored, and infants were classified as true or false positives. Neurosensory, cognitive, and behavioral outcomes were assessed using parent report.

RESULTS

Parents of 634 (57%) LMPT and 761 (62%) term-born infants completed the M-CHAT questionnaire. LMPT infants had significantly higher risk of a positive questionnaire screen compared with controls (14.5% vs 9.2%; relative risk [RR] 1.58; 95% CI 1.18, 2.11). After follow-up, significantly more LMPT infants than controls had a true positive screen (2.4% vs 0.5%; RR 4.52; 1.51, 13.56). This remained significant after excluding infants with neurosensory impairments (2.0% vs 0.5%; RR 3.67; 1.19, 11.3).

CONCLUSIONS

LMPT infants are at significantly increased risk for positive autistic screen. An M-CHAT follow-up interview is essential as screening for autism spectrum disorders is especially confounded in preterm populations. Infants with false positive screens are at risk for cognitive and behavioral problems.

Prenatal depression and 5-HTTLPR interact to predict dysregulation from 3 to 36 months--a differential susceptibility model

BACKGROUND

Childhood dysregulation, which reflects deficits in the capacity to regulate or control one's thoughts, emotions and behaviours, is associated with psychopathology throughout childhood and into adulthood. Exposures to adversity during the prenatal period, including prenatal depression, can influence the development of dysregulation, and a number of candidate genes have been suggested as moderators of prenatal exposure, including polymorphisms in the promoter region of the serotonin transporter gene (5-HTTLPR). We examined whether prenatal depression and child 5-HTTLPR interact to predict childhood dysregulation.

METHOD

Sample of N = 213 mother-child pairs from the Maternal Adversity, Vulnerability and Neurodevelopment (MAVAN) project. Mothers reported the IBQ-R at 3 and 6 months, and the ECBQ at 18 and 36 months, from which measures of dysregulation were extracted. Mothers' self-reported symptoms of depression on the CES-D at 24-36 weeks of gestation, and at 6, 12, 24 and 36 months postnatal. 5-HTTLPR genotype was extracted from buccal swabs. Mixed-model and confirmatory analyses were conducted.

RESULTS

Prenatal depression and 5-HTTLPR interacted to predict dysregulation from 3 to 36 months, within a model of strong differential susceptibility.

CONCLUSION

Children with S or LG alleles, when exposed to prenatal depression, have higher levels of dysregulation, and when exposed to lower or little prenatal depression, have higher capacity for regulation. Our findings support efforts to identify, support and treat prenatal depression.

Low-technology assisted reproduction and the risk of preterm birth in a hospital-based cohort

OBJECTIVE

To estimate the risk of preterm birth in singleton infants conceived through low-technology assisted reproduction (intrauterine insemination and/or ovulation induction/stimulation).

DESIGN

Hospital-based cohort study.

SETTING

University-affiliated hospital.

PATIENT(S)

Singleton babies born between 2001 and 2007 to 16,712 couples with no reported infertility (reference category), 378 babies conceived with low-technology treatment; 437 conceived with high-technology treatment; and 620 conceived naturally after a period of infertility.

INTERVENTION(S)

None. Treatment data were obtained from couples undergoing standard infertility investigation and care.

MAIN OUTCOME MEASURE(S)

Preterm birth, defined at three clinical endpoints: <37, <35, and <32 weeks of completed gestation.

RESULT(S)

After adjustment for age, parity, education, smoking, alcohol/drug use, and body mass index, the risk ratios and 95% confidence intervals (CI) of preterm birth for low technology were: 1.49 (CI: 1.12-2.00); 2.02 (CI: 1.30-3.13); and 2.93 (CI: 1.63-5.26) at <37, <35, and <32 weeks gestation, respectively, not dissimilar from the estimates for in vitro fertilization. Restricting the analysis to primiparas strengthened the association between treatment and preterm birth at the lower gestational endpoints. The increased risk persisted when the untreated group was used as the reference category, although the estimates were attenuated.

CONCLUSION(S)

In this large hospital-based cohort study, low-technology assisted reproduction appeared to be a moderately strong predictor of preterm birth, with similar associations observed in the high-technology treatment group. After adjusting for confounders, as well as the shared characteristics of infertile couples, associations were attenuated but remained significant, suggesting that part of the risk is likely attributable to the treatment.

Contextualizing racial disparities in preterm delivery: a rhetorical analysis of U.S. epidemiological research at the turn of the 21st century

Preterm delivery (PTD), defined as delivery prior to 37 weeks gestation, is a key contributor to persistent racial disparities in infant mortality in the United States. Five major funding initiatives were devoted to advancing PTD epidemiology during the 1990s and 2000s. By examining content and rhetorical features of 94 studies conducted under these initiatives, and published between 1993 and 2011, this paper considers how calls for more "contextual" approaches (focusing on social and environmental contexts) interacted with more "conventional" approaches (focusing on individual-level risk factors) to PTD epidemiology during this period. Contextual advocates initially emphasized complex biosocial reasoning to better connect social adversity with embodied outcomes. Yet responses by researchers invested in conventional approaches, as well as in studies published under new initiatives that explicitly claimed to incorporate contextual insights, often reframed this complex reasoning in biologically reductionist terms. Subsequent contextual advocates then focused on developing statistical methods to support research about social and environmental causes of PTD, and this strategy appears to have gained some traction with conventional researchers. These findings call for closer attention to language and power in both social scientific studies of epidemiological knowledge production, as well as among epidemiologists themselves.

Telephone interviews and online questionnaires can be used to improve neurodevelopmental follow-up rates

Background

Maximising response rates to neurodevelopmental follow-up is a key challenge for paediatric researchers. We have investigated the use of telephone interviews and online questionnaires to improve response rates, reduce non-response bias, maintain data completeness and produce unbiased outcomes compared with postal questionnaires when assessing neurodevelopmental outcomes at 2 years.

Methods

A prospective cohort study of babies born ≥32 weeks gestation. Neurodevelopmental outcomes were assessed at 2 years of age using a parent questionnaire completed via post, telephone or online. Relative Risks with 95% confidence intervals (RR; 95% CI) were calculated to identify participant characteristics associated with non-response and questionnaire response mode (postal vs. telephone/online). The proportion of missing data and prevalence of adverse outcomes was compared between response modes using generalized linear models.

Results

Offering telephone/online questionnaires increased the study response rate from 55% to 60%. Telephone/online responders were more likely to be non-white (RR 1.6; [95% CI 1.1, 2.4]), non-English speaking (1.6; [1.0, 2.6]) or have a multiple birth (1.6; [1.1, 2.3]) than postal responders. There were no significant differences in the prevalence of adverse neurodevelopmental outcomes between those who responded via post vs. telephone/online (1.1; [0.9, 1.4]). Where parents attempted all questionnaire sections, there were no significant differences in the proportion of missing data between response modes.

Conclusions

Where there is sufficient technology and resources, offering telephone interviews and online questionnaires can enhance response rates and improve sample representation to neurodevelopmental follow-up, whilst maintaining data completeness and unbiased outcomes.

Maternal lipids and small for gestational age birth at term

OBJECTIVE

To compare maternal lipid and lipoprotein concentrations between small for gestational age (SGA) infants and infants with normal growth born at term.

STUDY DESIGN

This was a case-control study nested within a large (n = 5337) prospective multicenter cohort of pregnant women followed to delivery. SGA cases (n = 323) were all term infants with birth weight below the 10th percentile for their gestational age and sex. Controls (n = 671) were selected at random from term infants with birth weight between the 25th and 75th percentiles. Plasma samples obtained at 24-26 weeks were analyzed for lipoproteins using a recently developed nuclear magnetic resonance-based procedure that distinguishes high-density lipoprotein (HDL) and low-density lipoprotein particles of different sizes. Apolipoprotein A-1 and C-II levels were analyzed using turbidimetric methods.

RESULTS

Compared with controls, mothers of SGA cases had significantly higher mean concentrations of total HDL particles, medium and small HDL particles, and apolipoprotein A-1, with evidence of a dose-response relationship across quartiles of the control distribution. aORs for the highest quartiles were 2.8 (95% CI, 1.7-4.5) for total HDL particles and 3.1 (95% CI, 1.9-5.0) for apolipoprotein A-1.

CONCLUSION

Our results suggest that the higher HDL particle and apolipoprotein A-1 concentrations in mothers of SGA cases may reflect defective placental transport of HDL, which could compromise cholesterol uptake by the developing fetus.

Maternal stress/distress, hormonal pathways and spontaneous preterm birth

BACKGROUND

Although second-trimester blood corticotrophin-releasing hormone (CRH) levels are robustly associated with preterm birth, the findings with respect to cortisol have been inconsistent, as have been those relating stress hormones to measured stressors and maternal distress.

METHODS

We measured plasma CRH, adrenocorticotrophic hormone (ACTH), cortisol, cortisol-binding globulin, oestradiol and progesterone at 24-26 weeks in a nested case-control study of 206 women who experienced spontaneous preterm birth and 442 term controls. We also related the hormonal levels to measures of environmental stressors, perceived stress and maternal distress (also assessed at 24-26 weeks) and to placental histopathology.

RESULTS

With the exception of an unexpectedly low oestradiol:progesterone ratio among cases (adjusted odds ratio = 0.5 [95% confidence interval 0.3, 0.8] for ratios above the median in controls), none of the hormonal measures was independently associated with spontaneous preterm birth; placental histopathological evidence of infection/inflammation, infarction or decidual vasculopathy; or measures of maternal stress or distress. CRH levels were positively associated with cortisol, but not with ACTH, whereas ACTH was also positively associated with cortisol.

CONCLUSIONS

Our findings suggest an intact pituitary-adrenal axis and confirm the positive feedback effect of cortisol on (placental) CRH. Neither of these hormonal pathways, however, was strongly linked to maternal stress/distress or to the risk of spontaneous preterm birth.

Comparative study of major depressive symptoms among pregnant women by employment status

The objectives of our study were to compare the prevalence of major depressive symptoms between subgroups of pregnant women: working women, women who had stopped working, housewives and students; and to identify risk factors for major depressive symptoms during pregnancy. The CES-D scale (Center for Epidemiological Studies Depression scale) was used to measure major depressive symptoms (CES-D score ≥23) in 5337 pregnant women interviewed at 24–26 weeks of pregnancy. Multivariate logistic regression models were developed to identify risk factors associated with major depressive symptoms. Prevalence of major depressive symptoms was 11.9% (11.0–12.8%) for all pregnant women. Working women had the lowest proportion of major depressive symptoms [7.6% (6.6–8.7%); n = 2514] compared to housewives [19.1% (16.5–21.8%); n = 893], women who had stopped working [14.4% (12.7–16.1%); n = 1665], and students [14.3% (10.3–19.1%); n = 265]. After adjusting for major risk factors, the association between pregnant women’s employment status and major depressive symptoms remained significant for women who had stopped working (OR: 1.61; 95% CI 1.26 to 2.04) and for housewives (OR: 1.46; 95% CI 1.10 to 1.94), but not for students (OR: 1.37; 95% CI 0.87 to 2.16). In multivariate analyses, low education, low social support outside of work, having experienced acute stressful events, lack of money for basic needs, experiencing marital strain, having a chronic health problem, country of birth, and smoking were significantly associated with major depressive symptoms. Health professionals should consider the employment status of pregnant women when they evaluate risk profiles. Prevention, detection and intervention measures are needed to reduce the prevalence of prenatal depression.

The most effective strategy for recruiting a pregnancy cohort: a tale of two cities

BACKGROUND

Pregnant women were recruited into the Alberta Pregnancy Outcomes and Nutrition (APrON) study in two cities in Alberta, Calgary and Edmonton. In Calgary, a larger proportion of women obtain obstetrical care from family physicians than from obstetricians; otherwise the cities have similar characteristics. Despite similarities of the cities, the recruitment success was very different. The purpose of this paper is to describe recruitment strategies, determine which were most successful and discuss reasons for the different success rates between the two cities.

METHODS

Recruitment methods in both cities involved approaching pregnant women (< 27 weeks gestation) through the waiting rooms of physician offices, distributing posters and pamphlets, word of mouth, media, and the Internet.

RESULTS

Between May 2009 and November 2010, 1,200 participants were recruited, 86% (1,028/1,200) from Calgary and 14% (172/1,200) from Edmonton, two cities with similar demographics. The most effective strategy overall involved face-to-face recruitment through clinics in physician and ultrasound offices with access to a large volume of women in early pregnancy. This method was most economical when clinic staff received an honorarium to discuss the study with patients and forward contact information to the research team.

CONCLUSION

Recruiting a pregnancy cohort face-to-face through physician offices was the most effective method in both cities and a new critically important finding is that employing this method is only feasible in large volume maternity clinics. The proportion of family physicians providing antenatal and post-natal care may impact recruitment success and should be studied further.

An inventory of Canadian pregnancy and birth cohort studies: research in progress

Background

A web-based inventory was developed as a voluntary registry of Canadian pregnancy and birth cohort studies, with the objective to foster collaboration and sharing of research tools among cohort study groups as a means to enrich research in maternal and child health across Canada.

Description

Information on existing birth cohort studies conducted in Canada exclusively or as part of broader international initiatives was accessed by searching the literature in PubMed and PsychInfo databases. Additional studies were identified by enquiring about the research activities of researchers at Canadian universities or working in affiliated hospitals or research centres or institutes. Of the fifty-eight birth cohort studies initially identified, forty-six were incorporated into the inventory if they were of a retrospective and/or prospective longitudinal design and with a minimum of two phases of data collection, with the first period having occurred before, during, or shortly after pregnancy and had an initial study sample size of a minimum of 200 participants.

Information collected from each study was organized into four main categories: basic information, data source and period of collection, exposures, and outcome measures and was coded and entered into an Excel spreadsheet. The information incorporated into the Excel spreadsheet was double checked, completed when necessary, and verified for completeness and accuracy by contacting the principal investigator or research coordinator. All data collected were then uploaded onto the website of the Institute of Human Development Child and Youth Health of the Canadian Institutes of Health Research. Subsequently, the database was updated and developed as an online searchable inventory on the website of the Maternal, Infant, Child and Youth Research Network.

Conclusions

This inventory is unique, as it represents detailed information assembled for the first time on a large number of Canadian birth cohort studies. Such information provides a valuable resource for investigators in the planning stages of cohort studies and identifying current research gaps.

Antenatal depressive symptoms among Canadian-born and immigrant women in Quebec: differential exposure and vulnerability to contextual risk factors

PURPOSE

To examine the distribution of contextual risk factors for antenatal depression according to immigrant status and the length of stay in Canada, to assess the association between these risk factors and antenatal depression (AD) for Canadian-born and immigrant women, and to compare the vulnerability of Canadian-born and immigrant women to risk factors in relation to antenatal depression.

METHODS

Women were recruited at routine ultrasound examinations (16-20 weeks), at antenatal blood sampling (8-12 weeks), or in antenatal care clinics. Cross-sectional analysis was performed on the baseline sample consisting of 5,162 pregnant women. CES-D scale was used to investigate depression. Levels of exposure to the selected risk factors according to immigrant status and length of stay were assessed using Chi-square-test or the t test. All measures of association were assessed using logistic regression. Multiplicative interaction terms were constructed between each of the risk factors and immigrant status to reveal differential vulnerability between Canadian-born and immigrant women.

RESULTS

Prevalence of AD (CES-D ≥16 points) was higher in immigrants (32% [29.6-34.4]) than in Canadian-born women (22.8% IC 95% [21.4-24.1]). Immigrant women were significantly more exposed than Canadian-born women to adverse contextual risk factors such as high marital strain, lack of social support, poverty, and crowding. At the same level of exposure to risk factors, Canadian-born women presented higher vulnerability to AD when lacking social support (OR = 4.14 IC 95% [2.69; 6.37]) while immigrant women presented higher vulnerability to AD when lacking money for basic needs (OR = 2.98 IC 95% [2.06; 4.32]).

CONCLUSIONS

Important risk factor exposure inequalities exist between Canadian-born and immigrant pregnant women. Interventions should target poverty and social isolation. The observed high frequency of AD highlights the need to evaluate the effectiveness of preventive interventions of antenatal depression.

Association of socioeconomic position with maternal pregnancy and infant health outcomes in birth cohort studies from Brazil and the UK

BACKGROUND

Socioeconomic inequalities in health outcomes are dynamic and vary over time. Differences between countries can provide useful insights into the causes of health inequalities. The study aims to compare the associations between two measures of socioeconomic position (SEP)-maternal education and family income-and maternal and infant health outcomes between ALSPAC and Pelotas cohorts.

METHODS

Birth cohort studies were started in Avon, UK, in 1991 (ALSPAC) and in the city of Pelotas, Brazil, in 1982, 1993 and 2004. Maternal outcomes included smoking during pregnancy, caesarean section and delivery not attended by a doctor. Infant outcomes were preterm birth, intra-uterine growth restriction (IUGR) and breast feeding for <3 months. The relative index of inequality was used for each measure of SEP so that results were comparable between cohorts.

RESULTS

An inverse association (higher prevalence among the poorest and less educated) was observed for almost all outcomes, with the exception of caesarean sections where a positive association was found. Stronger income-related inequalities for smoking and education-related inequalities for breast feeding were found in the ALSPAC study. However, greater inequalities in caesarean section and education-related inequalities in preterm birth were observed in the Pelotas cohorts.

CONCLUSIONS

Mothers and infants have more adverse health outcomes if they are from poorer and less well-educated socioeconomic backgrounds in both Brazil and the UK. However, our findings demonstrate the dynamic nature of the association between SEP and health outcomes. Examining differential socioeconomic patterning of maternal and infant health outcomes might help understanding of mechanisms underlying such inequalities.

Biopsychosocial risk factors for preterm birth and postpartum emotional well-being: a case-control study on Turkish women without chronic illnesses

AIMS AND OBJECTIVES

The study aimed to determine bio-psycho-social risk factors for preterm birth in a sample of Turkish women without chronic illnesses and evaluate their anxiety and depression in early postpartum period.

BACKGROUND

Preterm birth is a devastating event with long-term health and social implications. Studies have identified several risk factors; however, the contribution of these causes differs by ethnic groups.

DESIGN

This case-control study was conducted in a tertiary hospital in Istanbul over one year. In total, 149 preterm mothers were included in the case group and 150 term mothers who delivered in the same day with a case group woman were included in the control group. Chronic illnesses and anomalies were excluded.

METHOD

Data were gathered using a form that addressed risk factors for preterm birth. Multidimensional Scale of Perceived Social Support, Beck Depression Inventory and Spielberger's State-Trait Anxiety Inventory were administered within 24-72 hours after birth.

RESULTS

Logistic regression analysis revealed that partner's lower education (≤ 8 years), history of preterm birth, antenatal hospitalisation, genitourinary infection and irregular prenatal care were significant risk factors. Perceived social support from family and friends were significantly lower in preterm group. Preterm mothers experienced significantly more anxiety and depressive symptoms in early postpartum.

CONCLUSION

Many of the socio-economical and obstetric causes of preterm births were similar to other countries with higher preterm birth rates. Preterm births were associated with lower social support along with more anxiety and depressive symptoms in early postpartum.

RELEVANCE TO CLINICAL PRACTICE

Women who have established risk factors can be targeted for more intensive antenatal care for the prevention of preterm birth. Increased maternal anxiety and depression reveal the necessity of emotional support immediately after birth.

Contributions of immigration to depressive symptoms among pregnant women in Canada

OBJECTIVES

Immigrant women present high prevalence of depressive symptoms during pregnancy, the early postpartum period and as mothers of young children. We compared mental health of immigrant and Canadian native-born women during pregnancy according to length of stay and region of origin, and we assessed the role of economics and social support in antenatal depressive symptomatology.

METHODS

Data originated from the Montreal study on socio-economic differences in prematurity; 3834 Canadian-born and 1,495 foreign-born women attending Montreal hospitals for antenatal care were evaluated for depression at 24-26 weeks of pregnancy using the Center for Epidemiologic Studies Depression scale by fitting logistic regressions with staggered entry of possible explanatory variables.

RESULTS

Immigrant women had a higher prevalence of depressive symptomatology independently of time since immigration. Region of origin was a strong predictor of depressive symptomatology: women from the Caribbean, South Asia, Maghreb, Sub-Saharan Africa and Latin America had the highest prevalence of depressive symptomatology compared to Canadian-born women. The higher depression odds in immigrant women are attenuated after adjustment for lack of social support and money for basic needs. Time trends of depressive symptoms varied across origins. In relation to length of stay, depressive symptoms increased (European, Southeast Asian), decreased (Maghrebian, Sub-Saharan African, Middle Eastern, East Asian) or fluctuated (Latin American, Caribbean).

CONCLUSION

Depression in minority pregnant women deserves more attention, independently of their length of stay in Canada. Social support favouring integration and poverty reduction interventions could reduce this risk of antenatal depression.

Racial/ethnic disparities in obstetric outcomes and care: prevalence and determinants

Wide disparities in obstetric outcomes exist between women of different race/ethnicities. The prevalence of preterm birth, fetal growth restriction, fetal demise, maternal mortality, and inadequate receipt of prenatal care all vary by maternal race/ethnicity. These disparities have their roots in maternal health behaviors, genetics, the physical and social environments, and access to and quality of health care. Elimination of the health inequities because of sociocultural differences or access to or quality of health care will require a multidisciplinary approach. We aim to describe these obstetric disparities, with an eye toward potential etiologies, thereby improving our ability to target appropriate solutions.

Birth weight and risk of neuroblastoma: a meta-analysis

BACKGROUND

Neuroblastoma is the most common solid tumour in infancy but its aetiology is largely unknown. Prenatal factors might play a key role in its pathogenesis. Previous studies investigated whether birth weight is associated with risk of neuroblastoma, with conflictive results. We conducted a meta-analysis to quantitatively summarize the published evidence.

METHODS

Results from 10 case-control studies and one cohort study (1966 to December 2008) were included, involving a total of 3004 children with neuroblastoma. We constructed random-effects and fixed-effects models, performed 'pool-first' analyses, assessed heterogeneity and publication bias and performed sensitivity and influence analyses.

RESULTS

High birth weight (>4000 g) was associated with increased risk of neuroblastoma [odds ratio (OR) 1.19; 95% confidence interval (CI) 1.04-1.36]. Results for high birth weight were highly homogenous (I(2) = 0%). Low birth weight (<2500 g) was also related to increased risk of neuroblastoma (OR 1.24; 95% CI 1.0-1.55), but results were more heterogeneous (I(2 )= 30%). No evidence for particularly influential studies or for publication bias was found. However, sensitivity analysis indicated the presence of bias in studies on the association with low birth weight. Above 2500 g each 1000-g increase in birth weight was associated with a 13% (95% CI 3-25) increase in risk of neuroblastoma.

CONCLUSIONS

This meta-analysis shows that high birth weight is highly reproducibly associated with increased risk of neuroblastoma. The association with low birth weight was found to be less robust and deserves further studies.

Large prospective birth cohort studies on environmental contaminants and child health - goals, challenges, limitations and needs

The adverse health effects of environmental contaminants (ECs) are a rising public health concern, and a major threat to sustainable socioeconomic development. The developing fetuses and growing children are particularly vulnerable to the adverse effects of ECs. However, assessing the health impact of ECs presents a major challenge, given that multiple outcomes may arise from one exposure, multiple exposures may result in one outcome, and the complex interactions between ECs, and between ECs, nutrients and genetic factors, and the dynamic temporal changes in EC exposures during the life course. Large-scale prospective birth cohort studies collecting extensive data and specimen starting from the prenatal or pre-conception period, although costly, hold promise as a means to more clearly quantify the health effects of ECs, and to unravel the complex interactions between ECs, nutrients and genotypes. A number of such large-scale studies have been launched in some developed counties. We present an overview of "why", "what" and "how" behind these efforts with an objective to uncover major unidentified limitations and needs. Three major limitations were identified: (1) limited data and bio-specimens regarding early life EC exposure assessments in some birth cohort studies; (2) heavy participant burdens in some birth cohort studies may bias participant recruitment, and risk substantial loss to follow-up, protocol deviations limiting the quality of data and specimens collection, with an overall potential bias towards the null effect; (3) lack of concerted efforts in building comparable birth cohorts across countries to take advantage of natural "experiments" (large EC exposure level differences between countries) for more in-depth assessments of dose-response relationships, threshold exposure levels, and positive and negative effect modifiers. Addressing these concerns in current or future large-scale birth cohort studies may help to produce better evidence on the health effects of ECs.