scholarly journals Addressing special cases of bias that frequently occur in perinatal epidemiology

2020 ◽  
Author(s):  
Andreas M Neophytou ◽  
Marianthi-Anna Kioumourtzoglou ◽  
Dana E Goin ◽  
Kristin C Darwin ◽  
Joan A Casey
Keyword(s):  
Epidemiologic Study ◽  
Perinatal Outcomes ◽  
Adverse Outcomes ◽  
Time Varying ◽  
Perinatal Epidemiology ◽  
Special Cases ◽  
Pregnancy And Birth Outcomes ◽  
Race Ethnicity ◽  
Limited Period ◽  
Pregnancy And Birth

Abstract The epidemiologic study of pregnancy and birth outcomes may be hindered by several unique and challenging issues. Pregnancy is a time-limited period in which severe cohort attrition takes place between conception and birth and adverse outcomes are complex and multi-factorial. Biases span those familiar to epidemiologists: selection, confounding and information biases. Specific challenges include conditioning on potential intermediates, how to treat race/ethnicity, and influential windows of prolonged, seasonal and potentially time-varying exposures. Researchers studying perinatal outcomes should be cognizant of the potential pitfalls due to these factors and address their implications with respect to formulating questions of interest, choice of an appropriate analysis approach and interpretations of findings given assumptions. In this article, we catalogue some of the more important potential sources of bias in perinatal epidemiology that have more recently gained attention in the literature, provide the epidemiologic context behind each issue and propose practices for dealing with each issue to the extent possible.

Resistance Training During Pregnancy and Perinatal Outcomes

2014 ◽  
Vol 11 (6) ◽  
pp. 1141-1148 ◽  
Author(s):  
Erin White ◽  
Jim Pivarnik ◽  
Karin Pfeiffer
Keyword(s):  
Resistance Training ◽  
Aerobic Exercise ◽  
Online Survey ◽  
Mode Of Delivery ◽  
Perinatal Outcomes ◽  
Adverse Outcomes ◽  
Pregnancy And Birth Outcomes ◽  
Gestational Age At Delivery ◽  
Group Resistance ◽  
Pregnancy And Birth

Background:Approximately 10% of women engage in resistance training during pregnancy; however there is limited research on this activity. The purpose of this study was to examine associations between resistance training and adverse outcomes.Methods:Women completed an online survey and recalled their exercise habits during each trimester of their most recent pregnancy within the previous 5 years. Women also reported pregnancy and birth outcomes. Participants were then categorized into 3 groups based on leisure-time exercise: 1) Resistance + aerobic training (RTAE), 2) Aerobic exercise only (AE), and 3) no exercise (NE).Results:284 women completed the survey. Women in the RTAE group resistance trained on average 2.9 days/week for 27.3 minutes/session. The prevalences of hypertensive disorders (HD) and gestational diabetes mellitus (GDM) were significantly lower in the RTAE group when compared with the grouping of AE + NE women. Prepregnancy body mass index (BMI) was the strongest factor related to both GDM and HD. There was no difference in the risk of preterm labor, mode of delivery, or gestational age at delivery by exercise status.Conclusions:Our results suggest that women can safely engage in aerobic exercise and resistance training for muscular endurance 3 days/week for 30 minutes throughout gestation.

HPV Prevalence and its Association with Perinatal Outcomes among Singleton Mothers: Analysis of Pregnancy Risk Assessment and Monitoring System (PRAMS) Data, 2004-2011

2019 ◽  
Vol 15 (2) ◽  
pp. 143-149 ◽  
Author(s):  
Harpriya Kaur ◽  
Delf Schmidt-Grimminger ◽  
Baojiang Chen ◽  
K.M. Monirul Islam ◽  
Steven W. Remmenga ◽  
...  
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
Pregnant Women ◽  
Monitoring System ◽  
Large Population ◽  
Perinatal Outcomes ◽  
Hpv Infection ◽  
Adverse Outcomes ◽  
P Value ◽  
Pregnancy Risk

Background: Pregnancy may increase the risk of Human Papillomavirus (HPV) infection because of pregnancy induced immune suppression. The objective of this study was to use a large population-based dataset to estimate the prevalence of HPV infection and its association with adverse outcomes among pregnant women. Methods: We analyzed Pregnancy Risk Monitoring System data from 2004-2011 (N=26,085) to estimate the self-reported HPV infection. Survey logistic procedures were used to examine the relationship between HPV infection and adverse perinatal outcomes. Results: Approximately 1.4% of women were estimated to have HPV infection during their pregnancy. The prevalence of adverse outcomes in this sample was preterm birth (8.4%), preeclampsia (7.5%), low birth weight (6.3%) and premature rupture of membranes (2.8%). Compared to women without HPV infection, HPV infection positive women were much more likely to have had other infections such as chlamydia (9.23% vs. 2.12%, p-value <.0001), Group B Strep (21.7% vs. 10.04%, p-value <.0001), and herpes (7.17% vs. 1.07%, p-value <.0001). After adjusting for other risk factors including other infections, HPV infection was significantly associated with low birth weight (OR: 1.94, 95% CI: 1.14-3.30). Conclusion: The study indicated a potential association between HPV infection and low birth weight. Because pregnant women with HPV infection are at higher risk of other infections, future research may focus on the roles of co-infection in the development of adverse perinatal effects.

Finite-time control of uncertain time-varying systems in p-normal form

2020 ◽  
Author(s):  
Kanya Rattanamongkhonkun ◽  
Radom Pongvuthithum ◽  
Chulin Likasiri
Keyword(s):  
Normal Form ◽  
Finite Time ◽  
Control Law ◽  
Time Varying ◽  
Time Control ◽  
Special Cases ◽  
Time Varying Systems ◽  
A Chain ◽  
Uncertain Time ◽  
Power Integrator

Abstract This paper addresses a finite-time regulation problem for time-varying nonlinear systems in p-normal form. This class of time-varying systems includes a well-known lower-triangular system and a chain of power integrator systems as special cases. No growth condition on time-varying uncertainties is imposed. The control law can guarantee that all closed-loop trajectories are bounded and well defined. Furthermore, all states converge to zero in finite time.

scholarly journals The Cumulative Risk of Chemical and Nonchemical Exposures on Birth Outcomes in Healthy Women: The Fetal Growth Study

2019 ◽  
Vol 16 (19) ◽  
pp. 3700 ◽  
Author(s):  
Leah Zilversmit Pao ◽  
Emily W. Harville ◽  
Jeffrey K. Wickliffe ◽  
Arti Shankar ◽  
Pierre Buekens
Keyword(s):  
Birth Outcomes ◽  
Fetal Growth ◽  
Cumulative Risk ◽  
Logistic Models ◽  
Growth Curves ◽  
Adverse Outcomes ◽  
Risk Scores ◽  
Growth Study ◽  
Race Ethnicity ◽  
Pregnancy Weight

Metals, stress, and sociodemographics are commonly studied separately for their effects on birth outcomes, yet often jointly contribute to adverse outcomes. This study analyzes two methods for measuring cumulative risk to understand how maternal chemical and nonchemical stressors may contribute to small for gestational age (SGA). SGA was calculated using sex-specific fetal growth curves for infants of pregnant mothers (n = 2562) enrolled in the National Institute of Child Health and Human Development (NICHD) Fetal Growth Study. The exposures (maternal lead, mercury, cadmium, Cohen’s perceived stress, Edinburgh depression scores, race/ethnicity, income, and education) were grouped into three domains: metals, psychosocial stress, and sociodemographics. In Method 1 we created cumulative risk scores using tertiles. Method 2 employed weighted quantile sum (WQS) regression. For each method, logistic models were built with three exposure domains individually and race/ethnicity, adjusting for age, parity, pregnancy weight gain, and marital status. The adjusted effect of overall cumulative risk with three domains, was also modeled using each method. Sociodemographics was the only exposure associated with SGA in unadjusted models ((odds ratio) OR: 1.35, 95% (confidence interval) CI: 1.08, 1.68). The three cumulative variables in adjusted models were not significant individually, but the overall index was associated with SGA (OR: 1.17, 95% CI: 1.02, 1.35). In the WQS model, only the sociodemographics domain was significantly associated with SGA. Sociodemographics tended to be the strongest risk factor for SGA in both risk score and WQS models.

scholarly journals Characteristics and adverse outcomes of Chinese adolescent pregnancies between 2012 and 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yanxia Xie ◽  
Xiaodong Wang ◽  
Yi Mu ◽  
Zheng Liu ◽  
Yanping Wang ◽  
...  
Keyword(s):  
Adolescent Pregnancy ◽  
Gestational Age ◽  
Rural Areas ◽  
Reference Group ◽  
Perinatal Outcomes ◽  
Severe Anaemia ◽  
Adverse Outcomes ◽  
Near Miss ◽  
Adolescent Women ◽  
Adolescent Pregnancies

AbstractWe aimed to describe the characteristics of adolescent pregnancy, determine its effect on adverse maternal and perinatal outcomes and explore whether that association varies with gestational age with the goal of proposing specific recommendations for adolescent health in China. This study included 2,366,559 women aged 10–24 years who had singleton pregnancies between 2012 and 2019 at 438 hospitals. Adolescent pregnancy was defined as younger than 20 years of age. We used multivariable logistic regression to estimate the effects. Women aged 20–24 years served as the reference group in all analyses. The proportion of rural girls with adolescent pregnancies rebounded after 2015 even though common-law marriage in rural areas decreased. Higher risks of eclampsia (adjusted odds ratio (aOR) 1.87, 95% confidence interval (CI) 1.57 ~ 2.23), severe anaemia (aOR 1.18, 95% CI 1.09 ~ 1.28), maternal near miss (MNM; aOR 1.24, 95% CI 1.12 ~ 1.37), and small for gestational age (SGA; aOR 1.30, 95% CI 1.28 ~ 1.33) were observed when gestational age was > 37 weeks. Adolescent pregnancy was independently associated with increased risks of other perinatal outcomes. Further implementation of pregnancy prevention strategies and improved health care interventions are needed to reduce adolescent pregnancies and prevent adverse fertility outcomes among adolescent women in China at a time when adolescent fertility rate is rebounding.

Frailty, Race/Ethnicity, Functional Status, and Adverse Outcomes After Total Hip/Knee Arthroplasty: A Moderation Analysis

2021 ◽  
Author(s):  
Charlie Dharmasukrit ◽  
Sut Yee Shirley Chan ◽  
Richard L. Applegate ◽  
Daniel J. Tancredi ◽  
Theresa A. Harvath ◽  
...  
Keyword(s):  
Functional Status ◽  
Knee Arthroplasty ◽  
Adverse Outcomes ◽  
Total Hip ◽  
Moderation Analysis ◽  
Race Ethnicity
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