Browsing by Author "Lisonkova, Sarka"

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    The association between temporal changes in the use of obstetrical intervention and small- for-gestational age live births
    (BMC, 2015-09-29) Metcalfe, Amy; Lisonkova, Sarka; Joseph, KS
    Background: The literature attributes secular declines in small-for-gestational age (SGA) live births to changes in maternal smoking and other maternal characteristics. However, there are reasons to believe that the observed reductions in SGA may be a consequence of early delivery following obstetric intervention. Methods: We examined temporal trends in obstetrical intervention and SGA among singleton live births in the United States from 1990 to 2010. The modified Kitagawa decomposition, based on the fetuses-at-risk approach, was used to assess the relative contribution of changes in the gestational age distribution and gestational age-specific SGA to overall changes in SGA. Reductions in SGA rates due to a left shift in the gestational age distribution were assumed to primarily reflect increased obstetrical intervention, whereas decreases in overall SGA due to decreases in gestational-age-specific SGA rates were assumed to reflect declines in risk factors. Results: Temporal trends in SGA followed a non-linear pattern, with substantial declines from 10.1 % in 1990–92 to 8.9 % in 2002–04, followed by a small increase to 9.1 % in 2008–10. Rates of maternal smoking steadily decreased throughout the same time period and changes in SGA rates were more consistent with changes in the gestational age distribution. The modified Kitagawa decomposition analysis also attributed the initial decline in SGA rates to changes in the gestational age distribution. Conclusions: Complex temporal pattern in SGA rates cannot be explained by the linear pattern of changes in factors like maternal smoking. Changes in the gestational age distribution are more consistent with the observed secular trends in SGA rates.
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    Neonatal respiratory morbidity following exposure to chorioamnionitis
    (2017-05-17) Metcalfe, Amy; Lisonkova, Sarka; Sabr, Yasser; Stritzke, Amelie; Joseph, KS
    Abstract Background There are conflicting results in the literature on the impact of chorioamnionitis on neonatal respiratory morbidities. However, most studies are based on small clinical samples and fail to account for the competing risk of perinatal death. This study aimed to determine whether chorioamnionitis affects the incidence of respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD) after accounting for the increased risk of death. Methods Retrospective cohort study using linked birth and infant death registration and hospitalization records from Washington State between 2002 and 2011 (n = 763,671 singleton infants and n = 56,537 singleton preterm infants). Logistic regression models based on the traditional and fetuses-at-risk approaches were used to model two composite outcomes namely RDS and perinatal death and BPD and perinatal death. Confounders adjusted for in the models included maternal age, race, diabetes, hypertension, antenatal corticosteroids, mode of delivery and infant sex. Results While models using the traditional approach found a significant association only between chorioamnionitis and composite BPD and perinatal death (OR = 1.23, 95% CI: 1.01–1.50); using the fetuses-at-risk approach, there was a significant association between chorioamnionitis and both composite outcomes (RDS and perinatal death OR = 2.74, 2.50–3.01; BPD and perinatal death OR = 5.18, 95% CI: 4.39–6.11). Conclusion The fetuses-at-risk approach models the causal impact of chorioamnionitis on the development of the fetal lung and shows an increased risk of RDS, BPD and perinatal death associated with such maternal infection.