Elaine L. Duryea

A revised birth weight reference for the United States

OBJECTIVE: To generate birth weight curves based on the obstetric estimate of gestational age as specified in the revised 2003 U.S. birth certificate. METHODS: Using National Center for Health Statistics data from 2011, we constructed birth weight curves for neonates between 24 and 42 weeks of gestation. Curves were developed using the obstetric estimate of gestational age that is included in the revised 2003 U.S. birth certificate, which, when available, incorporates ultrasound dating information. Live-born singleton neonates between 500 and 6,000 g without malformations were included. These curves were compared with curves we generated using 1991 data on which the current national reference of Alexander and colleagues is based, a reference that used only last menstrual period to establish gestational age. RESULTS: The 1991 curves were based on 3,684,778 U.S. live births and the 2011 on 3,252,011 births. Birth weight percentile values were greater from 28 to 36 weeks of gestation in the 1991 data set. That is, the birth weights for preterm neonates were overestimated when 1991 reference curves were used compared with the proposed 2011 reference. For example, in 1991, a birth weight of 2,000 g was at the 50th percentile between 31 and 32 weeks of gestation, whereas in 2011, a birth weight of 2,000 g now corresponds to the 50th percentile between 33 and 34 weeks of gestation. CONCLUSIONS: Our revised reference curve for the United States provides an updated national reference for birth weight. LEVEL OF EVIDENCE: II

Maternal Human Immunodeficiency Virus Infection and Congenital Transmission of Cytomegalovirus

Objectives: To determine the frequency of congenital cytomegalovirus (CMV) infection in infants born to human immunodeficiency virus (HIV)-infected mothers and assess risk factors that may facilitate intrauterine transmission of CMV, including the role of perinatal HIV infection. Methods: Retrospective cohort study of infants who were born to HIV-infected mothers at Parkland Memorial Hospital and screened for congenital CMV infection according to a standard nursery protocol between February 1, 1997 and May 31, 2005. Results: During the 8-year study period that included 125,781 live births, there were 367 infants (0.3%) born to 303 HIV-infected mothers. Of 333 HIV-exposed infants who were screened for CMV, 10 (3%) had congenital CMV infection and 6 (60%) of these were identified only because of the CMV screening protocol. Four (1%) infants were infected with HIV, and none of these was CMV-infected. Compared with CMV-uninfected infants, CMV-infected, HIV-exposed newborns had lower mean birth weight (2508 versus 3148 g, P < 0.01), lower gestational age (37 vs. 39 weeks, P < 0.01), and higher median maternal HIV viral load at the start of prenatal care (15,411 vs. 2209 copies/mL, P = 0.02). CMV-infected infants were more likely to be born to mothers who were diagnosed with HIV during the pregnancy or at delivery (P = 0.03). Conclusions: The prevalence of congenital CMV infection among HIV-exposed newborns was 3%. Screening of these infants for CMV would allow identification of infants who are at risk for delayed onset of hearing loss and other neurodevelopmental impairment.

Glyburide in Women with Mild Gestational Diabetes: A Randomized Controlled Trial

OBJECTIVE: To evaluate whether the addition of glyburide to diet therapy modifies pregnancy outcomes in women with mild gestational diabetes. METHODS: Women with at least two abnormal values on a 3-hour, 100-g oral glucose tolerance test according to National Diabetes Data Group criteria and fasting values less than 105 mg/dL between 24 and 30 weeks of gestation were randomized to blinded glyburide or placebo study drug. All women were placed on a 35-kcal/kg diet and recorded four times daily capillary glucose measurements. The study drug was titrated based on weekly maternal capillary glucose values with targets of less than 95 mg/dL (5.3 mmol/L) and 120 mg/dL (6.7 mmol/L) for fasting and 2-hour postprandial glucose measurements, respectively. The primary study outcome was a 200-g birth weight decrement in neonates of women treated with glyburide. The sample size estimate for this outcome was 334 total randomized women with a one-to-one allocation. RESULTS: A total of 395 women were enrolled at a single center between September 2008 and October 2012. Women treated with glyburide had a significantly greater decline in fasting glucose values over the course of therapy. However, there was no difference in the primary study outcome. Specifically, the mean birth weight was 33 g lower in the group treated with glyburide (P=.52). Although not powered to examine all outcomes associated with gestational diabetes, treatment with glyburide did not affect need for operative delivery, shoulder dystocia, clavicular fracture, Erbs palsy, or neonatal hypoglycemia. Four women in each group required insulin. CONCLUSION: The addition of glyburide to diet therapy significantly improved maternal glycemic control over time when compared with placebo. However, adding glyburide to diet did not decrease birth weight or improve maternal or neonatal outcomes in women with mild gestational diabetes. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00744965. LEVEL OF EVIDENCE: I

The rate of preterm birth in the United States is affected by the method of gestational age assignment

OBJECTIVE The objective of the study was to examine the rate of preterm birth in the United States using 2 different methods of gestational age assignment and determine which method more closely correlates with the known morbidities associated with preterm birth. STUDY DESIGN Using National Center for Health Statistics data from 2012 United States birth certificates, we computed the rate of preterm birth defined as a birth at 36 or fewer completed weeks with gestational age assigned using the obstetric estimate as specified in the revised birth certificate. This rate was then compared with the rate when gestational age is calculated using the last menstrual period alone. The rates of neonatal morbidities associated with preterm birth were examined for each method of assigning gestational age. RESULTS The rate of preterm birth was 9.7% when the obstetric estimate is used to calculate gestational age, which is significantly different from the rate of 11.5% when gestational age is calculated using the last menstrual period alone. In addition, the neonates identified as preterm by obstetric estimate were more likely to qualify as low birthweight (54% vs 42%; P < .001) and suffer morbidities such as need for assisted ventilation and surfactant use than those identified with the last menstrual period alone. That is to say obstetric estimate is more sensitive and specific for preterm birth by all available markers of prematurity. CONCLUSION The preterm birth rate is 9.7% vs 11.5% and more closely correlates with adverse neonatal outcomes associated with preterm birth when gestational age is assigned using the obstetric estimate. This method of gestational age assignment is currently used by most industrialized nations and should be considered for future reporting of US outcomes.

The natural history of twin-twin transfusion syndrome stratified by Quintero stage.

Abstract Objective: To describe the natural history of expectantly managed twin–twin transfusion syndrome (TTTS) specific to disease stage. Methods: This was a retrospective study of monochorionic diamniotic pregnancies diagnosed with TTTS and delivered between 1997 and 2013. Staging was based on Quintero’s criteria, with sonogram images reviewed to confirm findings specific to stage. Progression and outcomes were evaluated in pregnancies that did not receive any form of therapy. Results: Thirty-eight pregnancies were diagnosed with TTTS and delivered at our institution, representing 1.6 per 10 000 births. Twenty were expectantly managed, of which 50% were stage I at presentation. Progression occurred in 45% of pregnancies, including 50% initially diagnosed with stage I TTTS. Seventy percent of pregnancies experienced survival of at least one twin, with no stillbirths or neonatal deaths if TTTS resolved. Pregnancies in which TTTS was either stable or improved had higher overall survival, compared with pregnancies that experienced progression, 86% versus 22%, p < 0.001, as well as more frequent survival of one or both twins, 91% versus 44%, p = 0.02. Conclusions: Among expectantly managed pregnancies with TTTS, most had early disease at diagnosis. Although 45% of cases progressed, which conferred poor prognosis, the majority experienced disease stabilization or improvement.

Sonography interval and the diagnosis of twin–twin transfusion syndrome

Abstract Objective: To evaluate the relationship between sonography surveillance interval and Quintero stage at diagnosis. Methods: This was a retrospective cohort study of monochorionic diamniotic pregnancies diagnosed with twin–twin transfusion syndrome (TTTS) and followed with serial sonography between 1997 and 2013. Women were divided into three cohorts: diagnosis at initial second-trimester sonogram, at a sonogram within 14 d of the prior exam, and at a sonogram greater than 14 d from the prior exam. Isolated amniotic fluid abnormalities were also recorded. Results: TTTS was identified in 48 pregnancies, with 50% of cases diagnosed at the initial sonogram, 21% within 14 d of a prior sonogram, and 29% more than 14 d from a prior sonogram. There was no association between interval and TTTS stage at diagnosis. Of 24 cases diagnosed during a follow-up sonogram, 46% had an isolated amniotic fluid abnormality preceding diagnosis. When isolated oligohydramnios (29%) or hydramnios (17%) was present, the sonography interval was significantly shorter (p = 0.003), but no difference in TTTS stage at diagnosis was found. Conclusions: Although frequent surveillance of monochorionic diamniotic pregnancies is prudent, when close follow-up of isolated fluid abnormalities was practiced, we were unable to demonstrate an effect of surveillance interval on stage of TTTS at diagnosis.

The Use of Protease Inhibitors in Pregnancy: Maternal and Fetal Considerations.

Background. Previous studies examining protease inhibitor use in pregnancy and the rate of preterm and small-for-gestational-age infants have yielded conflicting results. Methods. This was a retrospective study of HIV-infected women who delivered singleton infants at our institution between 1984 and 2014. Women with protease inhibitor use were compared to women on regimens without a protease inhibitor as well as those who received no antepartum antiretroviral therapy. Infants were considered preterm if less than 37 completed weeks of gestation and small-for-gestational-age if less than 10th percentile. Results. During the study period 1,004 pregnancies met inclusion criteria. Of those, 597 received a protease inhibitor as part of their regimen, 230 ART without a protease inhibitor, and 177 no ART. There was no difference in the rate of preterm birth between groups who received ART with or without a protease inhibitor, 14% versus 13%. There was no difference in the rate of small-for-gestational-age infants between the three groups. Use of a protease inhibitor was associated with a greater fall in viral load during pregnancy, p < 0.001. Conclusion. In this population with access to prenatal care and ART, treatment with protease inhibitors was associated with a greater fall in viral load, but not an increase in small or preterm infants.

The FL/AC ratio for prediction of shoulder dystocia in women with gestational diabetes

Abstract Purpose: To determine if sonographic variables, including fetal femur length to abdominal circumference (FL/AC) ratio, are associated with shoulder dystocia in women with gestational diabetes. Methods: This was a retrospective cohort study of women with gestational diabetes who delivered singleton infants at Parkland Hospital from 1997 to 2015. Diagnosis and treatment of gestational diabetes were uniform including sonography at 32–36 weeks. Biometric calculations were evaluated for correlation with shoulder dystocia. Results: During the study period, 6952 women with gestational diabetes underwent a sonogram at a mean gestation of 34.8 ± 1.8 weeks. Of 4183 vaginal deliveries, 66 experienced shoulder dystocia (16/1000). The FL/AC was associated with shoulder dystocia (p < 0.001) with an AUC of 0.70 (95% CI: 0.64–0.77). This was similar to age-adjusted AC and head circumference to AC ratio (HC/AC) (both with an AUC of 0.72). All other measurements, including estimated fetal weight, were inferior. When examining the 257 women with multiple sonograms after 32 weeks’ gestation, FL/AC was stable with advancing gestational age (p = 0.54) whereas age-adjusted AC and HC/AC were not (p < 0.001). Conclusions: The FL/AC is associated with shoulder dystocia in women with gestational diabetes. Additionally, it is a simple ratio that is independent of the reference used and remains stable, unlike age-adjusted AC and HC/AC ratio.

Influenza: Threat to Maternal Health

A maternal mortality rate of 1% was reported during the 2009-2010 influenza pandemic, with influenza in pregnancy posing a serious risk to maternal health. A high level of suspicion coupled with prompt diagnosis and treatment is paramount to minimizing morbidity and mortality. Vaccination during pregnancy should be of high priority to improve both maternal and neonatal outcomes.

Genitourinary Tuberculosis: A Rare Cause of Obstructive Uropathy in Pregnancy

Background. A rare but morbid form of extrapulmonary tuberculosis (TB), genitourinary TB is an important cause of obstructive uropathy and is likely underdiagnosed in pregnancy. Case. A 30-year-old primigravida undergoing treatment for active pulmonary TB presented with anuria at 13-14-weeks gestation. Bilateral ureteral strictures above the level of the ureterovesicular junctions were seen on imaging studies. Given her pulmonary disease, her obstructive uropathy was attributed to genitourinary TB. Bilateral percutaneous nephrostomy tubes were placed during pregnancy with successful ureteral reimplantation postpartum. Conclusion. Genitourinary TB should be considered as an etiology of urinary tract pathology during pregnancy, especially in foreign-born and immunocompromised persons. Early recognition resulting in prompt treatment can prevent further deterioration of maternal renal function and optimize pregnancy outcomes.