Roger B. Newman

Asthma during pregnancy

OBJECTIVE: To determine neonatal and maternal outcomes stratified by asthma severity during pregnancy by using the 1993 National Asthma Education Program Working Group on Asthma and Pregnancy definitions of asthma severity. The primary hypothesis was that moderate or severe asthmatics would have an increased incidence of delivery at <32 weeks of gestation compared with nonasthmatic controls. METHODS: This was a multicenter, prospective, observational cohort study conducted over 4 years at 16 university hospital centers. Asthma severity was defined according to the National Asthma Education Program Working Group on Asthma and Pregnancy classification and modified to include medication requirements. This study had 80% power to detect a 2- to 3-fold increase in delivery less than 32 weeks of gestation among the cohort with the moderate or severe asthma compared with controls. Secondary outcome measures included obstetrical and neonatal outcomes. RESULTS: The final analysis included 881 nonasthmatic controls, 873 with mild asthma, 814 with moderate, and 52 with severe asthma. There were no significant differences in the rates of preterm delivery less than 32 weeks (moderate or severe 3.0%, mild 3.4%, controls 3.3%; P = .873) or less than 37 weeks of gestation. There were no significant differences for neonatal outcomes except discharge diagnosis of neonatal sepsis among the mild group compared with controls, adjusted odds ratio 2.9, 95% confidence interval 1.2, 6.8. There were no significant differences for maternal complications except for an increase in overall cesarean delivery rate among the moderate-or-severe group compared with controls (adjusted odds ratio 1.4, 95% confidence interval 1.1, 1.8). CONCLUSION: Asthma was not associated with a significant increase in preterm delivery or other adverse perinatal outcomes other than a discharge diagnosis of neonatal sepsis. Cesarean delivery rate was increased among the cohort with moderate or severe asthma. LEVEL OF EVIDENCE: II-2

Racial/ethnic standards for fetal growth: The NICHD Fetal Growth Studies

OBJECTIVE Fetal growth is associated with long-term health yet no appropriate standards exist for the early identification of undergrown or overgrown fetuses. We sought to develop contemporary fetal growth standards for 4 self-identified US racial/ethnic groups. STUDY DESIGN We recruited for prospective follow-up 2334 healthy women with low-risk, singleton pregnancies from 12 community and perinatal centers from July 2009 through January 2013. The cohort comprised: 614 (26%) non-Hispanic whites, 611 (26%) non-Hispanic blacks, 649 (28%) Hispanics, and 460 (20%) Asians. Women were screened at 8w0d to 13w6d for maternal health status associated with presumably normal fetal growth (aged 18-40 years; body mass index 19.0-29.9 kg/m(2); healthy lifestyles and living conditions; low-risk medical and obstetrical history); 92% of recruited women completed the protocol. Women were randomized among 4 ultrasonography schedules for longitudinal fetal measurement using the Voluson E8 (GE Healthcare, Milwaukee, WI). In-person interviews and anthropometric assessments were conducted at each visit; medical records were abstracted. The fetuses of 1737 (74%) women continued to be low risk (uncomplicated pregnancy, absent anomalies) at birth, and their measurements were included in the standards. Racial/ethnic-specific fetal growth curves were estimated using linear mixed models with cubic splines. Estimated fetal weight (EFW) and biometric parameter percentiles (5th, 50th, 95th) were determined for each gestational week and comparisons made by race/ethnicity, with and without adjustment for maternal and sociodemographic factors. RESULTS EFW differed significantly by race/ethnicity >20 weeks. Specifically at 39 weeks, the 5th, 50th, and 95th percentiles were 2790, 3505, and 4402 g for white; 2633, 3336, and 4226 g for Hispanic; 2621, 3270, and 4078 g for Asian; and 2622, 3260, and 4053 g for black women (adjusted global P < .001). For individual parameters, racial/ethnic differences by order of detection were: humerus and femur lengths (10 weeks), abdominal circumference (16 weeks), head circumference (21 weeks), and biparietal diameter (27 weeks). The study-derived standard based solely on the white group erroneously classifies as much as 15% of non-white fetuses as growth restricted (EFW <5th percentile). CONCLUSION Significant differences in fetal growth were found among the 4 groups. Racial/ethnic-specific standards improve the precision in evaluating fetal growth.

Predicting success of external cephalic version.

OBJECTIVE Many authors have identified prognostic factors for external cephalic version success, but there has not been an attempt to integrate these factors into a simple, quantitative scoring system for predicting version success. Nor have any prognostic factors been prospectively tested. STUDY DESIGN We examined the clinical characteristics of 108 consecutive breech versions performed between 1984 and 1986. These characteristics were evaluated by stepwise linear regression and discriminate analysis to identify those factors associated with success. Five factors explained the majority of the variability in outcome (parity, placental location, dilation, station, and estimated fetal weight). A model was developed to incorporate the trends identified among these five variables to create a scoring system similar to that of Bishop. This scoring system was then applied to 286 women undergoing external cephalic version since October 1986. RESULTS There was a positive relationship between a rising version score and the likelihood of successful breech version. No versions were successful with a score < or = 2, and all breech versions were successful with a score of 9 or 10. The results of the version score may have significantly altered physician recommendations in more than one third of cases. CONCLUSION We believe that this simple, quantifiable scoring system is a refinement in our ability to predict the likelihood of external cephalic version success.

The Preterm Prediction Study: Association of cesarean delivery with increases in maternal weight and body mass index

OBJECTIVE Our purpose was to evaluate whether maternal weight and body mass index measured either before or during pregnancy are associated with an increased risk of cesarean delivery. STUDY DESIGN Maternal weight and height were prospectively collected on 2929 women in the National Institutes of Health Maternal-Fetal Medicine Units Network Preterm Prediction Study. Prepregnancy and 27- to 31-week maternal weight and height were used to calculate the body mass index, and its contribution to the risk of cesarean delivery was determined. Women with prenatally diagnosed congenital anomalies (n = 89) and pregestational diabetes (n = 31) were excluded from analysis. RESULTS Univariate analysis of risk factors for cesarean delivery in the 2809 eligible women revealed a decreased risk of cesarean delivery with maternal age < 18 years and multiparity; increased risk of cesarean delivery was noted with maternal age > 35 years and a male fetus. Increases in either prepregnancy or 27- to 31-week maternal weight (5-pound units) or body mass index (1.0 kg/m2 units) were significantly associated with an increased odds of cesarean delivery (p = 0.0001). Each unit increase in prepregnancy or 27- to 31-week body mass index resulted in a parallel increase in the odds of cesarean delivery of 7.0% and 7.8%, respectively. Multivariable stepwise logistic regression analysis confirmed the association of male fetus, age, nulliparity, and body mass index as significant variables contributing to cesarean delivery risk. CONCLUSIONS The risk of cesarean delivery is associated with incremental changes in maternal weight and body mass index before and during pregnancy after adjustment for potential confounding factors. Prepregnancy counseling about optimizing maternal weight and monitoring weight gain during pregnancy to decrease the risk of cesarean delivery are supported by this study.

Fetal anomaly detection by second-trimester ultrasonography in a tertiary center

OBJECTIVE Our purpose was to determine the relative accuracy of indicated versus screening second-trimester ultrasonography for detection of fetal anomalies and to assess the cost effectiveness of anomaly screening. STUDY DESIGN The study population consisted of 2031 pregnant women with singleton gestations who prospectively underwent ultrasonographic scanning between 15 and 22 weeks and received complete obstetric care at the Medical University of South Carolina between July 1, 1993, and June 30, 1996. Patients were divided into two groups: (1) indicated and (2) screening. The cost of screening ultrasonography was compared with the cost of newborn care for selected anomalous fetuses. RESULTS Forty-seven fetuses (2.3%) were diagnosed by ultrasonography as having a major anomaly: 8.6% in the indicated group and 0.68% in the screening group (p=0.001). The sensitivity for detecting the anomalous fetus was 75.0% overall: 89.7% in the indicated group and 47.6% in the screening group (p=0.001). Of the 47 patients diagnosed with fetal anomalies, 11 (23.4%) chose pregnancy termination; of the 35 (74.5%) live-born anomalous infants, 29 (82.9%) were discharged alive. Projected newborn cost savings offset the cost of routine midtrimester screening. CONCLUSIONS Detection of anomalous fetuses was significantly better in the indicated compared with the screening group. Nevertheless, routine ultrasonographic screening appeared cost-effective in our population.

Diagnosis of IUGR: Traditional Biometry

An important advance in obstetric medicine will be the improved ability to identify pathologic states of fetal growth, determine their consequences, and implement appropriate interventions. In response to utero-placental insufficiency and under nutrition, the fetus makes physiologic, metabolic, and hormonal adaptations which influence growth, including reducing metabolic dependence on glucose and increasing oxygenation of other nutritional substrates including amino acids and lactate. These endocrine changes combined with reduced nutrient supply divert amino acids from protein synthesis and tissue growth, resulting in impaired somatic growth and diminished growth of kidneys, liver, and heart-the developing organs with the highest rates of cellular turnover. The obstetrician must be able to recognize and accurately diagnosis the fetus with intrauterine growth restriction (IUGR). Ultrasonography is the accepted standard for monitoring fetal growth. Serial ultrasound measurements can provide a reasonable estimate of fetal gestational age and weight based on individual and composite fetal biometric measurements. The purpose of this chapter is to discuss those traditional biometric measurements as they relate to the diagnosis of IUGR.

Antenatal factors associated with significant birth weight discordancy in twin gestations.

OBJECTIVE The purpose of this study was to evaluate factors that are associated with significant birth weight discordancy. STUDY DESIGN As a part of an ongoing collaborative study of twins, maternal and fetal data were obtained from the medical records of twin gestations at eight medical centers. The study population was divided into groups by difference in birth weight discordancy (>or=20%, >or=25%, and >or=30%) RESULTS Severe birth weight discordancy was associated with fetal growth deceleration by 20 to 28 weeks (adjusted odds ratio, 4.90; 95% CI, 3.15-7.64) and between 28 weeks to birth (adjusted odds ratio, 3.48; 95% CI, 1.72-7.06). Antenatal bleeding (adjusted odds ratio, 1.86; 95% CI, 1.08-3.21), preeclampsia (adjusted odds ratio, 1.70, 95% CI, 1.21-2.41), and monochorionicity (adjusted odds ratio, 2.35, 95% CI, 11.71-3.23) were also associated with birth weight discordancy. CONCLUSION These data demonstrate the importance of the early diagnosis of placental chorionicity, because monochorionicity is associated with a 2-fold increase in birth weight discordancy in twin gestations.

Optimal nutrition for improved twin pregnancy outcome.

Twin pregnancies contribute a disproportionate degree to perinatal morbidity, partly because of increased risks of low birth weight and prematurity. Although the cause of the morbidity is multifactorial, attention to twin-specific maternal nutrition may be beneficial in achieving optimal fetal growth and birth weight. Achievement of body mass index (BMI)-specific weight gain goals, micronutrient and macronutrient supplementation specific to the physiology of twin gestations, and carbohydrate-controlled diets are recommended for optimal twin growth and pregnancy outcomes. The daily recommended caloric intake for normal-BMI women with twins is 40–45 kcal/kg each day, and iron, folate, calcium, magnesium, and zinc supplementation is recommended beyond a usual prenatal vitamin. Daily supplementation of docosahexaenoic acid and vitamin D should also be considered. Multiple gestation-specific prenatal care settings with a focus on nutritional interventions improve birth weight and length of gestation and should be considered for the care of women carrying multiples. Antepartum lactation consultation can also improve the rate of postpartum breastfeeding in twin pregnancies. Twin gestation-specific nutritional interventions seem effective in improving the outcome of these pregnancies and should be emphasized in the antepartum care of multiple gestations. This review examines the available evidence and offers recommendations for twin pregnancy-specific nutritional interventions.

Maternal obesity, uterine activity, and the risk of spontaneous preterm birth

OBJECTIVE: To assess the associations among maternal obesity, uterine contraction frequency, and spontaneous preterm birth in women at risk for spontaneous preterm birth. METHODS: In a secondary analysis, we analyzed data from 253 women at risk for spontaneous preterm birth (prior spontaneous preterm birth, vaginal bleeding) enrolled in a multicenter observational study of home uterine activity monitoring at 11 centers. All women wore a uterine activity monitor twice daily from 22 weeks through 34 weeks of gestation. Mean and maximal contractions/hour at 22–24, 25–26, 27–28, 29–30, 31–32 weeks, and at or after 33 weeks of gestation were compared between overweight/obese women (a body mass index [BMI] at 22–24 weeks greater than 25 kg/m2) and normal/underweight women (a BMI of 25 kg/m2 or less) at each gestational age interval. Multivariable analysis evaluated the influences of BMI, contractions, fetal fibronectin, and transvaginal cervical length on spontaneous preterm birth before 35 weeks. RESULTS: Obese/overweight women (n=156) were significantly less likely to experience spontaneous preterm birth before 35 weeks (8.3% compared with 21.7%, P<.01). For each gestational age interval before 32 weeks, obese/overweight women had fewer mean contractions/hour (P<.01 for each) and maximal contractions/hour (P<.01 for each) than normal/underweight women, although their mean cervical lengths (34.3 mm compared with 33.1 mm, P=.25), and fetal fibronectin levels (7.1% compared with 7.2% 50 ng/mL or more, P=.97) were similar at study enrollment. Obese/overweight status was associated with a lower risk of spontaneous preterm birth before 35 weeks after controlling for contraction frequency and other factors evaluated at 22–24 weeks, but not at later periods. CONCLUSION: Obese/overweight women at risk for spontaneous preterm birth exhibit less uterine activity and less frequent spontaneous preterm birth before 35 weeks of gestation than normal/underweight women. LEVEL OF EVIDENCE: II

Association of obesity with pulmonary and nonpulmonary complications of pregnancy in asthmatic women

OBJECTIVE: To evaluate whether maternal obesity is associated with pulmonary and nonpulmonary pregnancy complications in asthmatic women. METHODS: This is a secondary analysis of the prospective cohort Asthma During Pregnancy Study. Asthma patients were classified as having either mild or moderate to severe disease at the beginning of the study. Rates of pulmonary complications of asthma in asthmatic women and rates of nonpulmonary complications of pregnancy among asthma patients and controls, were compared between obese (body mass index ≥ 30 kg/m2) and nonobese women. RESULTS: Maternal body mass index and pregnancy outcome data were available for 1,699 of 1,812 asthmatic women and for 867 of 881 controls. Of the asthma subjects, 30.7% (521) were obese compared with 25.5% of the controls, P = .006. Obese women, regardless of whether they had asthma, were more likely to undergo cesarean delivery (OR 1.6, 95% confidence interval [CI]1.3–2.0) to develop preeclampsia or gestational hypertension (OR 1.7 95% CI 1.3–2.3) and gestational diabetes (OR 4.2, 95% CI 2.8–6.3). There were no differences in the rates of overall asthma improvement (20.6% compared with 23.6%, P = .36) or deterioration (33.3% compared with 28.8%, P = .20) between obese and nonobese asthma patients. After adjustment for confounding variables, obesity, not asthma, was associated with nonpulmonary complications of pregnancy, and obesity was associated with an increase in asthma exacerbations as well (OR 1.3, 95% CI 1.1–1.7). CONCLUSION: Obesity is associated with an increased risk of asthma exacerbations during pregnancy. The increased rate of nonpulmonary complications of pregnancy in asthma patients is associated with obesity in this population and not with asthma status. LEVEL OF EVIDENCE: II-1