The Association of H1N1 Pandemic Influenza with Congenital Anomaly Prevalence in Europe: An Ecological Time Series Study

Seasonal Variation of Congenital Diaphragmatic Hernia: A Review of the Literature and Database Report from the United States and Canada

INTRODUCTION

 The etiology of congenital diaphragmatic hernia (CDH) remains unknown and only 10 to 30% of patients have a genetic cause. Seasonal variation is known to contribute to the development of some congenital anomalies. Our aim was to investigate whether CDH births have seasonal variation.

MATERIALS AND METHODS

 A literature review was conducted for CDH and seasonality. Moreover, data from the CDH International Patient Registry Database were collected for infants with due dates between 2008 and 2014. Due dates were used to determine seasonal distribution of births. Birth rates per month in the United States and Canada were extracted from publicly available databases. Data were analyzed using analysis of variance and contingency tables.

RESULTS

 First, the literature review revealed 11 articles, of which 3 were eligible for inclusion. These studies reported conflicting results on seasonality of CDH. Second, we extracted due dates from the CDH International Patient Registry Database (1,259 patients) and found that there were fewer due dates in winter months (12.1 ± 4 patients/month) than in summer (16.7 ± 6 patients/month; p = 0.011) and fall months (16.3 ± 5 patients/month; p = 0.022). Although this trend was similar to that of all births in the United States and Canada, a lower incidence was observed in winter for CDH infants (20.2%) than for the general population (24.1%, p = 0.0012). CDH survival rate did not vary by season.

CONCLUSION

 This study provides evidence for a seasonal variation of CDH births. No causative link was established between CDH development and seasonality. Population-based studies with a focus on exposome data are needed to explain seasonal variation in CDH.

COVID-19 in pregnancy-what study designs can we use to assess the risk of congenital anomalies in relation to COVID-19 disease, treatment and vaccination?

BACKGROUND

The COVID-19 pandemic has accelerated pregnancy outcome research, but little attention has been given specifically to the risk of congenital anomalies (CA) and first trimester exposures.

OBJECTIVES

We reviewed the main data sources and study designs used internationally, particularly in Europe, for CA research, and their strengths and limitations for investigating COVID-19 disease, medications and vaccines.

POPULATION

We classify research designs based on four data sources: a) spontaneous adverse event reporting, where study subjects are positive for both exposure and outcome, b) pregnancy exposure registries, where study subjects are positive for exposure, c) congenital anomaly registries, where study subjects are positive for outcome and d) population healthcare data where the entire population of births is included, irrespective of exposure and outcome.

STUDY DESIGN

Each data source allows different study designs, including case series, exposed pregnancy cohorts (with external comparator), ecological studies, case-control studies and population cohort studies (with internal comparator).

METHODS

The quality of data sources for CA studies is reviewed in relation to criteria including diagnostic accuracy of CA data, size of study population, inclusion of terminations of pregnancy for foetal anomaly, inclusion of first trimester COVID-19-related exposures and use of an internal comparator group. Multinational collaboration models are reviewed.

RESULTS

Pregnancy exposure registries have been the main design for COVID-19 pregnancy studies, but lack detail regarding first trimester exposures relevant to CA, or a suitable comparator group. CA registries present opportunities for improving diagnostic accuracy in COVID-19 research, especially when linked to other data sources. Availability of inpatient hospital medication use in population healthcare data is limited. More use of ongoing mother-baby linkage systems would improve research efficiency. Multinational collaboration delivers statistical power.

CONCLUSIONS

Challenges and opportunities exist to improve research on CA in relation to the COVID-19 pandemic and future pandemics.

Immunological Changes in Pregnancy and Its Relation to COVID-19 Infection

This chapter describes the immunological adaptation to pregnancy. A special focus is drawn on the susceptibility to viral infections, especially COVID-19. Older literature refers to the pregnancy as an immunosuppressive state, while recent studies show an immunomodulation to adapt to the growing semiallograftic fetus. Despite this, pregnant women are not susceptible to all viral infections. Regarding influenza, pregnant women are not more susceptible to the infection, but more severe maternal courses. To prevent this, influenza vaccination is recommended for pregnant women. Based on the available evidence, pregnant patients are also not more susceptible to infection with regard to COVID-19 infection. Yet, more severe courses are described throughout gestation with the onset of obstetrical complications.

Epidemiology of birth defects based on a birth defect surveillance system in Southern Jiangsu, China, 2014-2018

Introduction: Changzhou has been confronted with great challenges in birth defects (BDs) prevention, as the prevalence rates of BDs in Changzhou increased rapidly. The aims of this study were to describe the epidemiology of BDs in perinatal infants (PIs, including dead fetus, stillbirth, or live birth between 28 weeks of gestation and 7 days after birth) in Changzhou during the period from 2014 to 2018.Methods: The BD surveillance data of PIs were collected from 56 hospitals of Changzhou. The prevalence rate of BDs with 95% confidence interval (CI) were calculated by Poisson distribution. Univariate and multivariate Poisson regression was performed to identify the changing trends of prevalence rates of BDs by year and the association of regarding BD characteristics including year, infant gender, maternal age, and season with BDs successively.Results: From 2014 to 2018, there were a total of 238,712 PIs of which 1707 had BDs, with the average prevalence of 71.509 per 10,000 PIs, showing a remarkable uptrend (aPRR = 1.133, 95%CI: 1.094-1.173). The ten leading BDs were polydactyly, congenital heart defects (CHD), syndactyly, microtia, cleft lip and palate (CLP), hypospadias, cleft palate, other malformation of external ear (OMEE), congenital atresia of rectum and anus, and congenital talipes equinovarus (CTE). During the study period, the prevalence rates of polydactyly, CHD and syndactyly increased significantly (PRR = 1.195, 95%CI: 1.109-1.288, PRR = 1.194, 95%CI: 1.105-1.291, and PRR = 1.143, 95%CI: 1.007-1.297, respectively); the prevalence rates of congenital esophageal atresia decreased significantly (PRR = 0.571, 95%CI: 0.395-0.826). The risk of BDs was higher in male PIs versus female PIs (aPRR = 1.235, 95%CI: 1.123-1.358).Conclusions: A significant increase in the prevalence of BDs was detected from 2014 to 2018 in Changzhou. CHD, polydactyly, and syndactyly increased much and congenital esophageal atresia declined much. Male PIs was risk factor for occurrence of BDs. Collecting information on factors associated with BDs, setting the report time of BDs system at smaller gestational age so as to get an exact prevalence and make better prevention strategy, strengthening the publicity and education, improving the ability of monitoring, and wider use of new diagnosis technology are important to reduce the prevalence of BDs in PIs.

Circulating Influenza Virus and Adverse Pregnancy Outcomes: A Time-Series Study

Individual-level epidemiologic studies of pregnancy outcomes after maternal influenza are limited in number and quality and have produced inconsistent results. We used a time-series design to investigate whether fluctuation in influenza virus circulation was associated with short-term variation in population-level rates of preterm birth, stillbirth, and perinatal death in Ontario between 2003 and 2012. Using Poisson regression, we assessed the association between weekly levels of circulating influenza virus and counts of outcomes offset by the number of at-risk gestations during 3 gestational exposure windows. The rate of preterm birth was not associated with circulating influenza level in the week preceding birth (adjusted rate ratio = 1.01, 95% confidence interval: 1.00, 1.02) or in any other exposure window. These findings were robust to alternate specifications of the model and adjustment for potential confounding. Stillbirth and perinatal death rates were similarly not associated with gestational exposure to influenza circulation during late pregnancy. We could not assess mortality outcomes relative to early gestational exposure because of missing dates of conception for many stillbirths. In this time-series study, population-level influenza circulation was not associated with short-term variation in rates of preterm birth, stillbirth, or perinatal death.