Ruofan Yao

Genetic Carrier Screening in the Twenty-first Century

Historically, carrier screening for a small number of autosomal recessive disorders has been offered to targeted populations based on ethnicity and family history. These chosen disorders are associated with severe morbidity or mortality, have a well-established carrier frequency in the targeted population, and have an acceptably high detection rate to make screening efficient. With advancing genetic technology, expanded panels rapidly are being designed and offered to the panethnic general population. This article reviews current recommendations for ethnicity-specific carrier screening for common disorders as well as the limitations and counseling complexities associated with expanded panels.

The effects of maternal obesity on perinatal outcomes among those born small for gestational age

Abstract Background: Maternal obesity has been associated with higher birth weight. Small for gestational age (SGA) neonates born to obese women may be associated with pathological growth with increased neonatal complications. Methods: This was a retrospective cohort study of all non-anomalous singleton neonates born in Texas from 2006–2011. Analyses were limited to births between 34 and 42 weeks gestation with birth weight ≤10th percentile. Results were stratified by maternal pre-pregnancy BMI class. The risk for stillbirth, neonatal death, neonatal intensive care unit (NICU) admission and five minute Apgar scores <7 were estimated for each obesity class and compared to the normal weight group. Multivariable logistic regression analyses were performed to control for potential confounding variables. Results: The rate of stillbirth was 1.4/1000 births for normal weight women, and 2.9/1000 among obese women (p < 0.001, aOR: 1.83 [1.43, 2.34]). The rate of neonatal deaths among normal weight women was 4.3/1000 births, whereas among obese women it was 4.7/1000 (p = 0.94, aOR: 1.10 [0.92, 1.30]). A dose-dependent relationship between maternal obesity and stillbirths was seen, but not for other neonatal outcomes. Conclusion: Among SGA neonates, maternal pre-pregnancy obesity was associated with increased risks for stillbirth, NICU admission and low Apgar scores but not neonatal death.

Association of maternal obesity with maternal and neonatal outcomes in cases of uterine rupture

OBJECTIVE To describe the risk of adverse outcomes associated with uterine rupture in the setting of maternal obesity. METHODS This was a retrospective cohort analysis of singleton nonanomalous neonates born after uterine rupture between 34 and 42 weeks of gestation. We derived data from the U.S. Natality Database from 2011 to 2014. Maternal prepregnancy body mass index (BMI) was categorized according to the World Health Organization classification. The rates of neonatal and maternal complications were calculated for each BMI class. Multivariable logistic regression analysis was used to estimate the risks of these complications among obese pregnancies compared with normal-weight pregnancies. RESULTS There were 3,942 cases of uterine rupture identified among 15,860,954 births (0.02%) between 2011 and 2014. Of these, 2,917 (74%) met inclusion criteria for analysis. There was an increased risk of low 5-minute Apgar score (22.9% compared with 15.9%; adjusted odds ratio [OR] 1.49 [1.19-1.87]), neonatal intensive care unit admission (31% compared with 24.6%; adjusted OR 1.51 [1.23-1.85]), and seizure (3.7% compared with 1.9%; adjusted OR 1.80 [1.05-3.10]) in obese compared with normal-weight pregnancies. The rate of prolonged assisted ventilation was 8.5% compared with 6.2% (P=.13), which, after adjustment for confounders, was a statistically significant difference (adjusted OR 1.47 [1.05-2.07]). The rate of neonatal death was similar (12.4 compared with 6.5/1,000 births; adjusted OR 2.03 [0.81-5.05]). The rates of various maternal complications were similar between groups. CONCLUSION In the setting of uterine rupture, maternal obesity moderately increases the risks of low Apgar score, neonatal intensive care unit admission, prolonged ventilation, and seizure. Risk of maternal complications and the risk of neonatal death, however, are similar to risks in patients of normal BMI.

The utility of an obesity-specific small for gestational age standard for pregnancies complicated by maternal obesity

Abstract Introduction: An obesity-specific standard for small for gestational age (SGA) pregnancies may help identify additional at risk pregnancies. Methods: This was a retrospective cohort study of all non-anomalous singleton neonates born in Texas from 2006–2011. Analysis was limited to births between 34 and 42 weeks gestation. Two SGA birth weight standards (birth weight ≤10th centile) were generated, one using the entire population (SGApop) and another using obese pregnancies (SGAcust). The outcomes of interest included: risks of stillbirth, neonatal death, 5-minute Apgar score below 7, NICU admission, and assisted ventilation >6 h. Results: Using the population standard, the prevalence of SGA complicated by obesity was 8.1%, compared with 10.3% using the obesity-specific standard. 10,457 additional pregnancies were identified as SGA. Compared to obese AGA pregnancies, the aHR for stillbirth was 5.45 [4.28, 6.94] for SGApop, and 1.21 [0.54, 2.74] for SGAcust-pop. The risks for the following neonatal complications were slightly higher for SGAcust-pop group compared to AGA group: neonatal death aOR 1.40 [1.05, 1.87], low 5-minute Apgar 1.31 [1.09, 1.57], and NICU admission 1.13 [1.03, 1.25]. These risks were lower than SGApop. Conclusions: Using an obesity-specific SGA standard, a subgroup of pregnancies with marginally increased risk for neonatal complications was identified.

Adverse perinatal outcomes associated with trial of labor after cesarean section at term in pregnancies complicated by maternal obesity

Abstract Introduction: Obesity is associated with higher risks for intrapartum complications. Therefore, we sought to determine if trial of labor after cesarean section (TOLAC) will lead to higher maternal and neonatal complications compared to repeat cesarean section (RCD). Methods: This was a retrospective cohort analysis of singleton nonanomalous births between 37 and 42 weeks GA complicated by maternal obesity (body mass index (BMI) ≥ 30 kg/m2) and history of one or two previous cesarean deliveries. Outcomes were compared between TOLAC and RCD. The maternal outcomes of interest included blood transfusion, uterine rupture, hysterectomy, and intensive care unit admission. Neonatal outcomes of interest included 5-minute Apgar score <7, prolonged assisted ventilation, neonatal intensive care unit admission, neonatal seizures, and neonatal death. Results: There were 538,264 pregnancies included. Compared with RCD, TOLAC was associated with an absolute increase in the following neonatal outcomes: low 5-min Apgar score (0.6%, p < .001), neonatal intensive care unit (NICU) admission (0.8%, p < .001), neonatal seizure (0.1 per 1000 births, p = .037), and neonatal death (0.2 per 1000 births, p = .028). Additionally, TOLAC was associated with an absolute increase in following maternal outcomes: blood transfusion (0.1%, p < .001), uterine rupture (0.18%, p < .001) and ICU admission (0.1%, p = .011). Conclusions: TOLAC among obesity pregnancies at term increases the risk of maternal and neonatal complications compared with RCD.

The impact of maternal body mass index on external cephalic version success

Abstract Objective: The purpose of this study is to determine the association between body mass index (BMI) and success of ECV. Methods: This is a cross-sectional analysis of singleton live births in the USA from 2010 to 2014 using birth certificate data. Patients were assigned a BMI category according to standard WHO classification. Comparisons of success of ECV between the BMI categories were made using chi-square analysis with normal BMI as the reference group. Cochran–Armitage test was performed to look for a trend of decreasing success of ECV as BMI increased. The odds for successful ECV were estimated using multivariate logistic regression analysis, adjusting for possible confounders. Results: A total of 51,002 patients with documented ECV were available for analysis. There was a decreased success rate for ECV as BMI increased (p < .01). Women with a BMI of 40 kg/m2 or greater had a 58.5% success rate of ECV; women with a normal BMI had 65.0% success rate of ECV. Multivariate analyses demonstrated significant decrease in success of ECV in women with BMI of 40 kg/m2 or greater (OR 0.621, CI 0.542–0.712). Among women with BMI of 40 kg/m2 or greater with successful ECV, 59.5% delivered vaginally. In contrast, 81.0% of women with normal BMI and successful ECV delivered vaginally. Conclusions: Morbidly obese women have decreased success rate of ECV as BMI increases and decreased vaginal delivery rates after successful ECV.