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The time between arrest of pregnancy development and miscarriage represents a window in which the pregnancy is nonviable and not developing. In effect, the pregnancy loss has already occurred, and additional exposure cannot influence its outcome. However, epidemiologic studies of miscarriage traditionally use gestational age at miscarriage (GAM) to assign time in survival analyses, which overestimates duration of exposure and time at risk. In Right From the Start, a pregnancy cohort study (2000-2012), we characterized the gap between estimated gestational age at arrest of development (GAAD) and miscarriage using transvaginal ultrasound in 500 women recruited from 3 states (North Carolina, Tennessee, and Texas). We compared effect estimates from models using GAAD with GAM to assign time at risk through a simulation study of several exposure patterns with varying effect sizes. The median gap between GAAD and miscarriage was 23 days (interquartile range, 15-32). Use of GAAD decreased the bias and variance of the estimated association for time-varying exposures, whereas half the time using GAM led to estimates that differed from the true effect by more than 20%. Using GAAD to assign time at risk should result in more accurate and consistent characterization of miscarriage risk associated with time-varying exposures.
© The Author(s) 2019. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: email@example.com.
BACKGROUND - Embryonal tumors arise typically in infants and young children and are often massive at presentation. Operative resection is a cornerstone in the multimodal treatment of embryonal tumors but potentially disrupts therapeutic timelines. When used appropriately, minimally invasive surgery can minimize treatment delays. The oncologic integrity and safety attainable with minimally invasive resection of embryonal tumors, however, remains controversial.
METHODS - Query of the Vanderbilt Cancer Registry identified all children treated for intracavitary, embryonal tumors during a 15-year period. Tumors were assessed radiographically to measure volume (mL) and image-defined risk factors (neuroblastic tumors only) at time of diagnosis, and at preresection and postresection. Patient and tumor characteristics, perioperative details, and oncologic outcomes were compared between minimally invasive surgery and open resection of tumors of comparable size.
RESULTS - A total of 202 patients were treated for 206 intracavitary embryonal tumors, of which 178 were resected either open (n = 152, 85%) or with minimally invasive surgery (n = 26, 15%). The 5-year, relapse-free, and overall survival were not significantly different after minimally invasive surgery or open resection of tumors having a volume less than 100 mL, corresponding to the largest resected with minimally invasive surgery (P = .249 and P = .124, respectively). No difference in margin status or lymph node sampling between the 2 operative approaches was detected (p = .333 and p = .070, respectively). Advantages associated with minimally invasive surgery were decreased blood loss (P < .001), decreased operating time (P = .002), and shorter hospital stay (P < .001). Characteristically, minimally invasive surgery was used for smaller volume and earlier stage neuroblastic tumors without image-defined risk factors.
CONCLUSION - When selected appropriately, minimally invasive resection of pediatric embryonal tumors, particularly neuroblastic tumors, provides acceptable oncologic integrity. Large tumor volume, small patient size, and image-defined risk factors may limit the broader applicability of minimally invasive surgery.
Copyright © 2018 Elsevier Inc. All rights reserved.
PURPOSE - To determine if women with leiomyomata detected using uniform ultrasound methods are at increased risk of cesarean birth, without regard to indication.
METHODS - Women were enrolled in Right from the Start (2000-2010), a prospective pregnancy cohort. Leiomyomata were counted, categorized, and measured during first trimester ultrasounds. Women provided information about demographics and reproductive history during first trimester interviews. Route of delivery was extracted from medical records or vital records, if the former were unavailable. Generalized estimating equations were used to calculate risk ratios (RR) and 95% confidence intervals (CIs) for the risk of cesarean birth by leiomyoma presence and characteristics.
RESULTS - Among 2635 women, the prevalences of leiomyomata and cesarean birth were 11.2% and 29.8%, respectively. Women with leiomyomata, compared with those without, had a 27% increase in cesarean risk (RR, 1.27; CI, 1.17-1.37). The association was weaker following adjustment for maternal body mass index and age (adjusted risk ratio [ARR], 1.11; CI, 1.02-1.20). The adjusted risk was elevated for women with a single leiomyoma 3 cm or more in diameter (ARR, 1.22; CI, 1.14-1.32) and women with the largest total leiomyoma volumes (ARR, 1.59; CI, 1.44-1.76).
CONCLUSIONS - Women with leiomyomata were at increased risk for cesarean birth particularly, those with larger tumor volumes.
Copyright © 2014 Elsevier Inc. All rights reserved.
OBJECTIVE - To estimate the association between over-the-counter nonsteroidal anti-inflammatory drug (NSAID) exposure during the early first trimester and risk for spontaneous abortion (gestation before 20 weeks of gestation) in a prospective cohort.
METHODS - Women were enrolled in the Right from the Start study (2004-2010). Exposure data regarding over-the-counter NSAID use from the last menstrual period (LMP) through the sixth week of pregnancy were obtained from intake and first-trimester interviews. Pregnancy outcomes were self-reported and verified by medical records. Gestational age was determined from the LMP. Stage of development before loss was determined from study ultrasonography. Cox proportional hazards regression models were used to estimate the association between NSAID exposure and pregnancy outcome taking into account candidate confounders.
RESULTS - Among 2,780 pregnancies, 367 women (13%) experienced a spontaneous abortion. NSAID exposure was reported by 1,185 (43%) women. NSAID exposure was not associated with spontaneous abortion risk in unadjusted models (hazard ratio [HR] 1.01, 95% confidence interval [CI] 0.82-1.24) or models adjusted for maternal age (adjusted HR 1.00, 95% CI 0.81-1.23).
CONCLUSION - Our findings suggest that use of nonprescription over-the-counter NSAIDs in early pregnancy does not put women at increased risk of spontaneous abortion.
BACKGROUND - Prior evidence linking first-trimester bleeding with preterm birth (PTB, <37 weeks gestation) risk has been inconsistent and may be biased by subject selection and/or incomplete documentation of bleeding episodes for all participants. Prior studies have not carefully examined the role of bleeding characteristics in PTB risk. In the present study, we estimate the association between first-trimester bleeding and PTB in a non-clinical prospective cohort and test whether bleeding characteristics better predict risk.
METHODS - Women were enrolled in Right from the Start (2000-2009), a prospective pregnancy cohort. Data about bleeding and bleeding characteristics were examined with logistic regression to assess association with PTB.
RESULTS - Among 3978 pregnancies 344 were PTB and 3634 term. Bleeding was reported by 986 (26%) participants. After screening candidate confounders, only multiple gestations remained in the model. Bleeding associated with PTB [odds ratio (OR)(adjusted) = 1.40, 95% confidence interval (CI) 1.09-1.80]. Risk did not vary by race/ethnicity. Compared with non-bleeders, PTB risk was higher for bleeding with red color (OR(adjusted) = 1.92, 95% CI, 1.32-2.82), for heavy episodes (OR(adjusted) = 2.40, 95% CI 1.18-4.88) and long duration (OR(adjusted) = 1.67, 95% CI 1.17-2.38).
CONCLUSIONS - Bleeding associated with PTB was not confounded by common risk factors for bleeding or PTB. PTB risk was greatest for women with heavy bleeding episodes with long duration and red color and would suggest that combining women with different bleeding characteristics may affect the accuracy of risk assessment. These data suggest a candidate etiologic pathway for PTB and warrant further investigation of the biologic mechanisms.
We tested the hypothesis that the protective effect of parity on fibroids is due to direct pregnancy-related effects by following women from early pregnancy to postpartum period with ultrasound. Of 171 women with one initial fibroid, 36% had no identifiable fibroid at the time of postpartum ultrasound, and 79% of the remaining fibroids decreased in size.
Copyright © 2010 American Society for Reproductive Medicine. All rights reserved.
OBJECTIVE - To ascertain the likelihood of identifying small for gestational age (SGA) neonates prenatally (below the 10th percentile for gestational age).
METHODS - On admission for delivery, the charts of singletons with reliable gestational age (GA) were reviewed to determine whether intrauterine growth restriction (IUGR) was suspected, clinically or sonographically. Multiple logistic regression analysis was used with the accurate identification of SGA as the dependent variable and 13 independent variables.
RESULTS - Over 10 months, 1502 pregnant women met the inclusion criteria and 16% of neonates were born SGA. Before delivery, only 10% (95% confidence interval 6%-14%) of newborns identified as SGA were detected, and 7% weighed below the 5th percentile. Multiple logistic regression analysis identified 4 factors that made a significant independent contribution to the detection of SGA: younger maternal age, size less than date, sonographic examination within 4 weeks of delivery, and a history of substance abuse.
CONCLUSIONS - Because we failed to identify 90% of SGA with fundal height measurements, the likelihood of detecting most growth-restricted fetuses clinically is low. If other investigators confirm these findings, a paradigm shift is warranted to improve the detection of IUGR.
Copyright 2010 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.
OBJECTIVES - To create a fetal size nomogram for use in sub-Saharan Africa and compare the derived centiles with reference intervals from developed countries.
METHODS - Fetal biometric measurements were obtained at entry to antenatal care (11-22 weeks' gestation) and thereafter at 4-week intervals from pregnant women enrolled in a longitudinal ultrasound study in Kinshasa, Democratic Republic of Congo. The study population comprised 144 singleton gestations with ultrasound-derived gestational age within 14 days of the menstrual estimate. A total of 755 monthly ultrasound scans were included with a mean +/- SD of 5 +/- 1 (range, 2-8) scans per woman. Estimated fetal weight (EFW) was calculated at each ultrasound examination using the Hadlock algorithm. A general mixed-effects linear regression model that incorporated random effects for both the intercept and slope was fitted to log-transformed EFW to account for both mean growth and within-fetus variability in growth. Reference centiles (5(th), 10(th), 50(th), 90(th) and 95(th) centiles) were derived from this model.
RESULTS - Nomograms derived from developed populations consistently overestimated the 50(th) centile EFW value for Congolese fetuses by roughly 5-12%. Differences observed in the 10(th) and 90(th) centiles were inconsistent between nomograms, but generally followed a pattern of overestimation that decreased with advancing gestational age.
CONCLUSIONS - In low-resource settings, endemic malaria and maternal nutritional factors, including low prepregnancy weight and pregnancy weight gain, probably lead to lower fetal weight and utilization of nomograms derived from developed populations is not appropriate. This customized nomogram could provide more applicable reference intervals for diagnosis of intrauterine growth restriction in sub-Saharan African populations.
Miscarriage is a common and poorly understood adverse pregnancy outcome. In this study, the authors sought to evaluate the relation between self-reported use of prenatal vitamins in early pregnancy and the risk of miscarriage. Between 2000 and 2008, 4,752 US women were prospectively enrolled in Right From the Start. Information about vitamin use was obtained from a first-trimester interview. Discrete-time hazard models were used, candidate confounders were assessed, and the following variables were included in the model: study site, maternal age, gravidity, marital status, education, race/ethnicity, smoking, and use of progesterone in early pregnancy. Approximately 95% of participants reported use of vitamins during early pregnancy. A total of 524 women had a miscarriage. In the final adjusted model, any use of vitamins during pregnancy was associated with decreased odds of miscarriage (odds ratio = 0.43, 95% confidence interval: 0.30, 0.60) in comparison with no exposure. These results should be viewed in the context of a potentially preventive biologic mechanism mitigated by possible confounding by healthy behaviors and practices that are also associated with vitamin supplement use during pregnancy.
OBJECTIVE - To estimate the proportion of pregnant women with one or more leiomyomas detected by research-quality ultrasound screening in the first trimester, to describe the size and location of leiomyomas identified, and to report variation in prevalence by race/ethnicity.
METHODS - Within an ongoing prospective cohort, we conducted 4,271 first-trimester or postmiscarriage ultrasound examinations. Sonographers measured each leiomyoma three separate times, recording the maximum diameter in three perpendicular planes each time. Sonographers and investigators classified type and location.
RESULTS - Among 458 women with one or more leiomyomas (prevalence 10.7%), we identified a total of 687 leiomyomas. The mean size of the largest leiomyoma was 2.3 cm (95% confidence interval [CI] 1.8-2.8). Mean gestational age at ultrasonography was 61+/-13 days from last menstrual period. Prevalence varied by race/ethnicity: 18% in African-American women (95% CI 13-25), 8% in white women (95% CI 7-11), and 10% in Hispanic women (95% CI 5-19). The proportion of women with leiomyomas increased with age much more steeply for African-American women than for white women.
CONCLUSION - Leiomyomas are common in pregnancy and occur more often among African-American women. Given the limited research on effects of leiomyomas on reproductive outcomes, the degree to which race/ethnic disparities in prevalence of leiomyomas may contribute to disparities in events such as miscarriage and preterm birth warrants investigation.