Biomedical subjects

Yvonne W Cheng

Publications and source records attributed to Yvonne W Cheng.

14 recordsLinked to original sources

PubMed2006

Are women who are treated for hypothyroidism at risk for pregnancy complications?

OBJECTIVE: The purpose of this study was to investigate the outcomes that are associated with pregnancy and treated hypothyroidism. STUDY DESIGN: This was a retrospective cohort study of all women who received prenatal care and were delivered at the University of California, San Francisco, between 1989 and 2001. All patients with hypothyroidism diagnosed before pregnancy or early in pregnancy were identified. Maternal, fetal, and obstetric outcomes were then collected and analyzed for women with hypothyroidism and compared with women without hypothyroidism. RESULTS: Among 20,499 deliveries, there were 419 women (2.1%) who were treated for hypothyroidism during the study period. Hypothyroidism was more common among women > or =35 years old, white women, and women without Medicaid insurance. Treated hypothyroidism was not associated with any increase in maternal, fetal, or neonatal complications. In addition, hypothyroidism did not affect mode of delivery. CONCLUSION: Compared with patients without hypothyroidism, patients with treated hypothyroidism are not at any increased risk for perinatal morbidity.

Adult↗

PubMed2006

Face presentation: predictors and delivery route.

OBJECTIVE: We sought to identify associated characteristics of face presentation and to examine factors that were associated with mode of delivery in the setting of face presentation. STUDY DESIGN: This was a retrospective cohort study of women who were diagnosed with face presentation during labor. We examined maternal, fetal, and labor characteristics to determine the associations and predictors of cesarean delivery. RESULTS: Fetuses in face presentation were more likely preterm, < 2500 g, and black. An Apgar score of < 7 at 5 minutes was more common in face presentation (10.9%) compared with vertex presentation (4.4%; P = .018). Rates of umbilical artery base excess < -12 or pH < 7.0 were not different. Cesarean delivery was less common in women who received oxytocin (adjusted odds ratio, 0.18; 95% CI, 0.03-0.95) and in women with mentum anterior (14%) as compared with mentum posterior presentation (85%; P < .001). CONCLUSION: This study confirms the association between face presentation and prematurity. The association with black ethnicity may be related to differences in pelvic anatomy. Although face presentation was associated with decreased Apgar scores, no other indicators of fetal asphyxia were identified. Cesarean delivery rates were higher in women with mentum posterior face presentation and in women who did not receive oxytocin.

Apgar Score↗

PubMed2006

Perinatal complications among different Asian-American subgroups.

OBJECTIVE: This study was undertaken to investigate the differences in perinatal outcomes among Asian American/Pacific Islander (AAPI) women. STUDY DESIGN: A retrospective cohort study of all Japanese, Chinese, and Filipina women who delivered at University of California, San Francisco from 1985 to 2001 examined the incidence of gestational diabetes, preeclampsia, and preterm delivery. RESULTS: Among the 6511 women delivered during the study period, the incidence of preeclampsia was highest among Filipina women (6.8%) compared with the Chinese and Japanese women (4.0% and 3.7%, respectively, P < .001). Gestational diabetes was most common in the Chinese and Filipina women (6.5% and 6.1%, respectively) compared with the Japanese women (3.4%, P = .013). Preterm delivery was also highest among Filipina women both before 37 weeks (12.2%, P < .001) and 34 weeks (4.8%, P = .004). These differences remained statistically significant after controlling for potential confounding variables. CONCLUSION: We found significant differences in rates of preeclampsia, gestational diabetes, and preterm delivery in the Chinese, Japanese, and Filipino subgroups. In studies of race and ethnicity, it is important to examine Asian subgroups separately.

Adult↗

PubMed2006

Women with one elevated 3-hour glucose tolerance test value: are they at risk for adverse perinatal outcomes?

OBJECTIVE: The purpose of this study was to examine whether women with one elevated value of the 3-hour glucose tolerance test are at increased risk for adverse perinatal outcomes. STUDY DESIGN: This was a retrospective cohort study of singleton pregnancies that were screened for gestational diabetes mellitus with the use of the glucose loading test and with a glucose tolerance test for follow up, if screened values were positive. Perinatal outcomes in women with one elevated glucose tolerance test value were compared with the outcomes in women who screened negative by glucose loading test. The chi-square test was used to compare categorical outcomes, and multivariate logistic regression analysis was used to control for potential confounding factors; a P value of < .05 indicated statistical significance. RESULTS: Of 14,036 women who met the study criteria, women with one elevated glucose tolerance test value exhibited higher rates of cesarean delivery (in nulliparous women only), preeclampsia, chorioamnionitis, birth weight > 4000 g and > 4500 g, and neonatal admission to the intensive care nursery as compared with women who screened negative (P < .05 for all). CONCLUSION: Although women with one elevated glucose tolerance test value are not diagnosed with gestational diabetes mellitus, they are still at risk for adverse perinatal outcomes.

Adult↗

PubMed2006

Manual rotation of the fetal occiput: predictors of success and delivery.

OBJECTIVE: The purpose of the study was to define predictors of successful rotation and rate of cesarean delivery after manual rotation of the fetal occiput from occiput posterior or transverse position. STUDY DESIGN: A retrospective cohort study comprised patients who underwent a trial of manual rotation of the fetal occiput from occiput posterior or occiput transverse position. Successful rotation was defined as delivery in the occiput anterior position. We examined maternal, fetal, and labor characteristics as predictors of both fetal position at delivery and cesarean delivery. RESULTS: Multiparity (odds ratio, 2.5; 95% CI, 1.5-3.8) and maternal age < 35 years (odds ratio, 2.0; 95% CI, 1.1-3.4) were associated with successful manual rotation of the fetal occiput. After successful rotation, the cesarean delivery rate was 2%, compared with 34% if the rotation failed (P < .001). Asian ethnicity, nulliparity, age > 35 years, labor induction, and epidural usage were associated with higher rates of cesarean delivery. CONCLUSION: After successful manual rotation of the fetal occiput, women had lower cesarean delivery rates than women with unsuccessful rotations. Multiparity and maternal age of < 35 years were associated with more successful rotations.

Adult↗

PubMed2006

Are there ethnic differences in the length of labor?

OBJECTIVE: The purpose of this study was to examine the lengths of the first and second stages of labor among different racial/ethnic groups to determine whether different norms should be established. STUDY DESIGN: This was a retrospective cohort study of all laboring, term, singleton, vertex deliveries in a single academic institution. Median lengths of first and second stages of labor were compared among 4 racial/ethnic groups: black, Asian, white, and Latina. Kruskal-Wallis, Wilcoxon rank sum tests, and multivariate linear and logistic regression models were performed. RESULTS: In 27,521 births, the lengths of first stage of labor did not differ significantly among groups in the multivariate analysis. In the second stage of labor, black women had shorter labors, both overall and stratified by epidural use. In the multivariate analysis, when controlled for demographics, parity, epidural, chorioamnionitis, birthweight, delivery year, and labor management, black women had a shorter second stage than did white women (nulliparous women, 22 minutes; multiparous women, 7.5 minutes; P < .001) and lower rates of prolonged second stage (odds ratio, 0.6; P < .001). Nulliparous Asian women had a significantly longer second stage and higher rates of prolonged second stage, and nulliparous Latina women had a shorter second stage, compared with nulliparous white women. CONCLUSION: When data are controlled for confounding factors, black women had a shorter length of second stage of labor than did women in other ethnic groups. These differences appear to be clinically significant. This contributes to the support of a multifactorial redefinition of labor curves, which are used widely in the management of labor.

Black or African American↗

PubMed2006

The relationship of fetal position and ethnicity with shoulder dystocia and birth injury.

OBJECTIVE: The objective of this study was to examine factors associated with the occurrence of shoulder dystocia and subsequent perinatal outcomes. STUDY DESIGN: We conducted a retrospective cohort study of 29,612 consecutive term, singleton, vertex vaginal deliveries. The primary outcome was reported shoulder dystocia. Fetal position, ethnicity, and their interaction terms were examined along with maternal characteristics, induction and length of labor, operative vaginal delivery, epidural, and birth weight in both bivariate and multivariate analyses. RESULTS: Among women who met study criteria, 524 (1.8%) experienced a shoulder dystocia. African American women had the highest risk of shoulder dystocia (2.6%), compared with other races/ethnicities (P = .001). Women who delivered in occiput posterior position were noted to have a lower risk for shoulder dystocia (1.1%) as compared with occiput anterior position (1.8%, P = .046). However, in the setting of a shoulder dystocia, a higher risk of brachial plexus injury was observed in neonates delivered in occiput posterior position (adjusted odds ratio 10.4, 95% confidence interval 3.03 to 35.88) by vacuum-assisted vaginal delivery (adjusted odds ratio 3.24, 95% confidence interval 1.37 to 7.67) and neonates weighing 4000 g or more (adjusted odds ratio 2.53, 95% confidence interval 1.09 to 5.85). CONCLUSION: Overall African American women have an increased risk of shoulder dystocia, but their neonates are not more likely to experience birth injury. Although occiput posterior position has a protective effect for shoulder dystocia, the risk of brachial plexus injury is increased in the setting of a persistent occiput posterior delivery. These factors should be used to consider a patient's prospective risk for shoulder dystocia and associated outcomes.

Adult↗

PubMed2006

Induction of labor and cesarean delivery by gestational age.

OBJECTIVE: Studies of cesarean delivery (CD) rates among women undergoing induction of labor (IOL) often compare such women to women experiencing spontaneous labor at similar gestational ages. We sought to examine the association between IOL at various gestational ages and CD, accounting for the effect of increased gestational age among the comparison group who were managed expectantly. STUDY DESIGN: We conducted a retrospective cohort study of all term, singleton, cephalic presentation pregnancies delivered at our institution over 15 years excluding cesarean deliveries before labor. For each gestational age of induction, we created a comparison group of women who were undelivered at that gestational age, and who experienced labor at some future gestational age. RESULTS: In women undergoing IOL at 38 weeks gestation, the CD rate was 11.9% as compared to 13.3% (P = .42) of women beyond 38 weeks gestation. The CD rate for induction of labor compared to ongoing pregnancy was 14.3% versus 15.0% (P = .62) at 39 weeks, 20.4% versus 19.0% (P = .41) at 40 weeks, and 24.3% versus 26.0% (P = .39) at 41 weeks. When controlling for potential confounding, there was a higher rate of CD among women with expectant management beyond 38 weeks (adjusted odds ratio [AOR] 1.80; 95% CI 1.29-2.53), 39 weeks (1.39; 95% CI 1.08-1.80), and 40 weeks (AOR 1.27; 95% CI 1.00-1.62). CONCLUSION: Our findings suggest that IOL may not increase a woman's risk of CD when compared to expectant management. While this question has been addressed prospectively at 41 weeks gestation, it requires further examination at earlier gestations and among various subgroups.

Cesarean Section↗

PubMed2006

Associated factors and outcomes of persistent occiput posterior position: A retrospective cohort study from 1976 to 2001.

OBJECTIVE: To identify maternal and fetal risk factors associated with persistent occiput posterior position at delivery, and to examine the association of occiput posterior position with subsequent obstetric outcomes. METHODS: This is a retrospective cohort study of 30 839 term, cephalic, singleton births. Women with persistent occiput posterior (OP) position at delivery were compared to those with occiput anterior (OA) position. Demographics, obstetric history, and labor management were evaluated and subsequent obstetric outcomes examined. Potential confounding variables were controlled for using multivariate logistic regression analysis. RESULTS: The overall frequency of OP position was 8.3% in the study population. When compared to Caucasians, a higher rate of OP was observed among African-Americans (OR = 1.4, 95% CI 1.25-1.64) while no other racial/ethnic differences were noted. Other associated factors included nulliparity, maternal age > or =35, gestational age > or =41 weeks, and birth weight >4000 g, as well as artificial rupture of the membranes (AROM) and epidural anesthesia (p < 0.001 for all). Persistent OP was associated with increased rates of operative vaginal (OR = 4.14, 95% CI 3.57-4.81) and cesarean deliveries (OR = 13.45, 95% CI 11.94-15.15) and other peripartum complications including third or fourth degree perineal lacerations (OR = 2.38, 95% CI 2.03-2.79), and chorioamnionitis (OR = 2.10, 95% CI 1.81-2.44). CONCLUSION: Epidural use, AROM, African-American ethnicity, nulliparity, and birth weight >4000 g are associated with persistent OP position at delivery, with higher rates of operative deliveries and obstetric complications. This information can be useful in counseling patients regarding risks and associated outcomes of persistent OP position.

Adult↗

PubMed2006

Screening or diagnostic: markedly elevated glucose loading test and perinatal outcomes.

OBJECTIVE: To determine the diagnostic value of markedly elevated 50-g glucose loading test results (>or=200 mg/dL) and associated perinatal outcomes. METHOD: This was a retrospective cohort study of 14 771 pregnancies screened for gestational diabetes mellitus (GDM) between 1988 and 2001. The positive predictive value of the 50-g oral glucose loading test (GLT) results as measured by plasma glucose value was examined. Perinatal outcomes were assessed for women with GLT results >or=200 mg/dL compared to GLT <200 mg/dL, stratified by the diagnosis of GDM. Statistical comparisons were made using the Chi-square test and Student's t-test and potential confounding factors were controlled for using multivariable logistic regression analyses. A p value <0.05 and 95% confidence intervals were used to indicate statistical significance. RESULTS: The positive predictive values for a GDM diagnosis were 62% for GLT results between 180 and 189 mg/dL, 79% for those between 200 and 209 mg/dL, and 100% for GLT results >or=230 mg/dL. Compared to women with a GLT result <200 mg/dL, among women not diagnosed with GDM but with a GLT >or=200 mg/dL the adjusted odds ratio (aOR) for cesarean delivery was 4.18 (95% confidence intervals, 1.15-15.2). These women also had higher aORs for preterm delivery <32 weeks (aOR = 8.05 (1.02-63.6)), shoulder dystocia (aOR = 15.14 (1.64-140)), and their neonates were more likely to have a 5-minute Apgar score <7 (aOR = 6.41 (1.23-33.3)). For women diagnosed with GDM and with a GLT >or=200 mg/dL, the aOR for cesarean delivery was also elevated compared to those with a GLT <200 mg/dL (aOR = 2.24 (1.19-4.21)). CONCLUSION: A GLT value of >or=200 mg/dL is not absolutely diagnostic for gestational diabetes but is associated with unfavorable perinatal outcomes.

Cohort Studies↗

PubMed2006

The association between persistent occiput posterior position and neonatal outcomes.

OBJECTIVE: To examine the effect of persistent occiput posterior position on neonatal outcome. METHODS: This is a retrospective cohort study of 31,392 term, cephalic, singleton births. Women with neonates born in persistent occiput posterior position at delivery were compared to those with occiput anterior position. Women with occiput transverse position were excluded. The association between occiput posterior position and neonatal outcomes, including 5-minute Apgar scores, umbilical cord gases, meconium-stained amniotic fluid, meconium aspiration syndrome, birth trauma, admission to the intensive care nursery, and length of stay were examined using chi(2) and Student t tests. Potential confounders (maternal age, ethnicity, parity, gestational age, epidural anesthesia, labor induction, length of labor, meconium, chorioamnionitis, birth weight, and year of delivery) were controlled for by using multivariable logistic regression and linear regression analyses. RESULTS: There were 2,591 (8.2%) neonates delivered in occiput posterior position of the total cohort of 31,392 deliveries. Compared with occiput anterior, neonates delivered in occiput posterior position had higher risks for adverse outcomes, including 5-minute Apgar score less than 7 (odds ratio [OR] 1.50, 95% confidence interval [CI] 1.17-1.91), acidemic umbilical cord gases (OR 2.05, 95% CI 1.52-2.77), meconium-stained amniotic fluid (OR 1.29, 95% CI 1.17-1.42), birth trauma (OR 1.77, 95% CI 1.22-2.57), admission to the intensive care nursery (OR 1.57, 95% CI 1.28-1.92), and longer neonatal stay in the hospital (OR 2.69, 95% CI 2.22-3.25). CONCLUSION: Persistent occiput posterior position at delivery is associated with higher risks of adverse neonatal outcomes compared with neonates delivered in the occiput anterior position. This information may be important in counseling women who experience persistent occiput posterior position in labor. LEVEL OF EVIDENCE: II-2.

Adult↗

PubMed2006

Gestational weight gain and adverse neonatal outcome among term infants.

OBJECTIVE: To examine the relationship between gestational weight gain and adverse neonatal outcomes among infants born at term (37 weeks or more). METHODS: This was a retrospective cohort study of 20,465 nondiabetic, term, singleton births. We performed univariable and multivariable analyses of the associations between gestational weight gain and neonatal outcomes. We categorized gestational weight gain by the Institute of Medicine guidelines as well as extremes of gestational weight gain (less than 7 kg and more than 18 kg). RESULTS: Gestational weight gain above the Institute of Medicine guidelines was more common than gestational weight gain below (43.3% compared with 20.1%). In multivariable analyses, gestational weight gain above guidelines was associated with a low 5-minute Apgar score (adjusted odds ratio [AOR] 1.33, 95% confidence interval [CI] 1.01-1.76), seizure (AOR 6.50, 95% CI 1.43-29.65), hypoglycemia (AOR 1.52, 95% CI 1.06-2.16), polycythemia (AOR 1.44, 95% CI 1.06-1.94), meconium aspiration syndrome (AOR 1.79, 95% CI 1.12-2.86), and large for gestational age (AOR 1.98, 95% CI 1.74-2.25) compared with women within weight gain guidelines. Gestational weight gain below guidelines was associated with decreased odds of neonatal intensive care unit admission (AOR 0.66, 95% CI 0.46-0.96) and increased odds of small for gestational age (SGA; AOR 1.66, 95% CI 1.44-1.92). Gestational weight gain less than 7 kg was associated with increased risk of seizure, hospital stay more than 5 days, and SGA. Gestational weight gain more than 18 kg was associated with assisted ventilation, seizure, hypoglycemia, polycythemia, meconium aspiration syndrome, and large for gestational age. CONCLUSION: Gestational weight gain above guidelines was common and associated with multiple adverse neonatal outcomes, whereas gestational weight gain below guidelines was only associated with SGA status. Public health efforts among similar populations should emphasize prevention of excessive gestational weight gain.

Analysis of Variance↗

PubMed2005

Screening for gestational diabetes: different cut-offs for different ethnicities?

OBJECTIVE: To examine whether screening guidelines for gestational diabetes should be modified based on ethnicity. STUDY DESIGN: This is a retrospective cohort study of 14,565 pregnancies screened for gestational diabetes. The primary outcome of interest was the diagnosis of gestational diabetes based on the results of the 100-g glucose tolerance test. A diagnosis was determined if any 2 of the 4 values (fasting or 1-, 2-, or 3-hour postprandial) were at or above 95, 180, 155, or 140 mg/dL, respectively. Values of the 50-g glucose-loading test were examined from 130 mg/dL to 150 mg/dL. The sensitivity, specificity, false-positive rates, and positive predictive values of various glucose-loading test cut-offs were compared among whites, African Americans, Latinas, and Asians. The sensitivities and specificities were compared using receiver-operator characteristic curves. RESULTS: Sensitivity and specificity of the glucose-loading test differ by ethnicity. Generally, African Americans achieved the highest sensitivities and specificities over the range examined. To achieve a false-positive rate of 10% for the glucose-loading test, the threshold value would be 133 mg/dL for African Americans, 140 mg/dL for whites, 143 mg/dL for Latinas, and 147 mg/dL for Asians. At the lower glucose-loading test values (130 and 135 mg/dL), Asians exhibited the highest positive predictive values (30.0% and 34.0%), whereas at higher values of the glucose-loading test (145 and 150 mg/dL), African Americans had the highest positive predictive values (46.0% and 51.5%). Throughout the glucose-loading test range, whites had the lowest positive predictive values (P < .001). CONCLUSIONS: To maximize the sensitivity and minimize the false-positive rate of the glucose-loading test, it may be reasonable to consider varying the threshold based on ethnicity. However, modification of glucose-loading test thresholds based on maternal ethnicity merit further study to determine whether improved perinatal outcomes can be achieved.

Adult↗

PubMed2004

How long is too long: Does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes?

OBJECTIVE: The purpose of this study was to examine maternal and neonatal outcomes in relation to lengthening intervals of the second stage of labor. STUDY DESIGN: This is a retrospective cohort study of 15,759 nulliparous, term, cephalic, singleton births at the University of California, San Francisco, between 1976 and 2001. The second stage of labor was divided into 1-hour intervals. Maternal and neonatal outcomes were compared with the use of chi-squared and Student t tests, and a probability value of < or =.05 was used to indicate statistical significance. Potential confounders were controlled for with multivariate logistic regression. RESULTS: Increasing rates of cesarean delivery, operative vaginal delivery, and perineal trauma were associated with the second stage beyond the first hour. In multivariate analysis, the >4-hour interval group had higher rates of cesarean delivery (odds ratio, 5.65; P < .001), operative vaginal deliveries (odds ratio, 2.83; P < .001), 3rd- or 4th-degree perineal lacerations (odds ratio, 1.33; P = .009), and chorioamnionitis (odds ratio, 1.79; P < .001). There were no differences in neonatal acid-base status associated with length of second stage. However, there were fewer neonates with a 5-minute Apgar score of <7 (odds ratio, 0.45; P = .01). CONCLUSION: Although the length of the second stage of labor is not associated with poor neonatal outcome, a prolonged second stage is associated with increased maternal morbidity and operative delivery rates.

Analysis of Variance↗