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Biomedical subjects

George R Saade

Publications and source records attributed to George R Saade.

At least 19 recordsLinked to original sources
PubMed2006

Prediction of shoulder dystocia using multivariate analysis.

We evaluated the use of multivariate analysis in the prediction of shoulder dystocia (SD). One hundred consecutive cases with SD were matched with 100 controls without dystocia. All patients had term, vaginal delivery. Multivariate analysis was used to identify independent variables significantly related to shoulder dystocia. The regression coefficients for the identified factors were used to calculate a composite score from which receiver operating characteristics (ROC) curves were derived. Birthweight (BW), 1-hour Glucola (GLU), operative vaginal delivery (OVD), and height of fundus (HOF) were related independently to SD. The sensitivity and specificity reached 84 and 80%, respectively, with BW + GLU + OVD. Significant associations persisted when HOF and carbohydrate intolerance were substituted for BW and GLU, respectively. SD is independently associated with BW, GLU, and OVD, and may be predicted with clinically acceptable accuracy using multiple variables. This model may be useful in the design of prospective studies for managing suspected macrosomia.

Adult↗
PubMed2006

Management of uterine hyperstimulation with concomitant use of oxytocin and terbutaline.

The purpose of this study was to evaluate the efficacy of the concomitant use of subcutaneous terbutaline and oxytocin for the management of uterine hyperstimulation. Patients in active labor receiving intravenous oxytocin who developed uterine hyperstimulation were randomly assigned to receive either oxytocin discontinuation or administration of subcutaneous terbutaline while maintaining the oxytocin infusion. Time to resolution of hyperstimulation was the primary end point. Twenty-nine patients were enrolled. The most frequent types of hyperstimulation were tachysystole (26%) and mixed patterns (26%). Resolution time was significantly shorter in the combination therapy versus control ( P = 0.002). Persistence of hyperstimulation 15 minutes after intervention was seen in 53% of the women in the control group versus 0% of the women in the study group. No significant differences were noted in the Apgar scores, rates of cesarean sections, or chorioamnionitis. In the management of uterine hyperstimulation, subcutaneous terbutaline without discontinuation of oxytocin is more effective than the traditional approach of oxytocin discontinuation.

Adult↗
PubMed2006

Labor-associated gene expression in the human uterine fundus, lower segment, and cervix.

BACKGROUND: Preterm labor, failure to progress, and postpartum hemorrhage are the common causes of maternal and neonatal mortality or morbidity. All result from defects in the complex mechanisms controlling labor, which coordinate changes in the uterine fundus, lower segment, and cervix. We aimed to assess labor-associated gene expression profiles in these functionally distinct areas of the human uterus by using microarrays. METHODS AND FINDINGS: Samples of uterine fundus, lower segment, and cervix were obtained from patients at term (mean +/- SD = 39.1 +/- 0.5 wk) prior to the onset of labor (n = 6), or in active phase of labor with spontaneous onset (n = 7). Expression of 12,626 genes was evaluated using microarrays (Human Genome U95A; Affymetrix) and compared between labor and non-labor samples. Genes with the largest labor-associated change and the lowest variability in expression are likely to be fundamental for parturition, so gene expression was ranked accordingly. From 500 genes with the highest rank we identified genes with similar expression profiles using two independent clustering techniques. Sets of genes with a probability of chance grouping by both techniques less than 0.01 represented 71.2%, 81.8%, and 79.8% of the 500 genes in the fundus, lower segment, and cervix, respectively. We identified 14, 14, and 12 those sets of genes in the fundus, lower segment, and cervix, respectively. This enabled networks of co-regulated and co-expressed genes to be discovered. Many genes within the same cluster shared similar functions or had functions pertinent to the process of labor. CONCLUSIONS: Our results provide support for many of the established processes of parturition and also describe novel-to-labor genes not previously associated with this process. The elucidation of these mechanisms likely to be fundamental for controlling labor is an important prerequisite to the development of effective treatments for major obstetric problems--including prematurity, with its long-term consequences to the health of mother and offspring.

Cervix Uteri↗
PubMed2006

Effects of progesterone on iNOS, COX-2, and collagen expression in the cervix.

This study examines the relationship between inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the control of cervical ripening and parturition under normal (normal term pregnancy) and abnormal (preterm labor and prolongation of pregnancy) conditions by (a) measuring changes in the collagen both visually and quantitatively, (b) localizing and characterizing iNOS and COX-2 under normal conditions, and (c) characterizing the changes in iNOS and COX-2 under abnormal conditions. Cervices are obtained from estrus and timed pregnant Sprague-Dawley rats (n=4-10 per group). Preterm labor is induced with Onapristone (3 mg/rat; progesterone antagonist) and the prolongation of pregnancy with progesterone (2.5 mg, twice daily). Collagen changes are measured and visualized with the picrosirius polarization method. RT-PCR is used to characterize the mRNA expression (p<0.05), and immunohistochemistry is used to localize the protein expression for iNOS and COX-2. The organization and birefringence of the collagen during pregnancy decreased and is supported by changes in the luminosity (p<0.001). The iNOS and COX-2 enzymes were localized in cervical smooth muscle, vascular smooth muscle, and epithelium. Under normal conditions, iNOS mRNA levels decreased as COX-2 mRNA levels increased demonstrating an inverse correlation (Spearman r = -0.497; p=0.00295). Onapristone stimulated preterm labor, increasing the iNOS and COX-2 mRNA (p<0.05). The increase demonstrated a positive correlation (Spearman r = 0.456; p=0.03). Progesterone prolonged pregnancy, decreasing the iNOS and COX-2 mRNA (p=0.036). In conclusion, there may be an interaction between the nitric oxide and prostaglandin pathways in cervical ripening and parturition.

Animals↗
PubMed2006

Characterization of abdominally acquired uterine electrical signals in humans, using a non-linear analytic method.

The present work seeks to determine if a particular non-linear analytic method is effective at quantifying uterine electromyography (EMG) data for estimating the onset of labor. Twenty-seven patients were included, and their uterine EMG was recorded non-invasively for 30 min. The patients were grouped into two sets: G1: labor, N = 14; G2: antepartum, N = 13. G1 patients all delivered spontaneously within 24 h of recording while G2 patients did not. The uterine electrical signals were analyzed offline by first isolating the uterine-specific frequency range and then randomly selecting "bursts" of uterine electrical activity (each associated with a uterine contraction) from every recording. Wavelet transform was subsequently applied to each of the bursts' traces, and then the fractal dimension (FD) of the resulting transformed EMG burst-trace was calculated (Benoit 1.3, Trusoft). Average burst FD was found for each patient. FD means for G1 and G2 were calculated and compared using t test. FD was significantly higher (P < 0.05) for G1: 1.27 +/- 0.03 versus G2: 1.25 +/- 0.02. The wavelet-decomposition-generated fractal dimension can be used to successfully discern between patients who will deliver spontaneously within 24 h and those who will not, and can be useful for the objective classification of antepartum versus labor patients.

Abdomen↗
PubMed2006

Adaptation to pregnancy leads to attenuated rat uterine artery smooth muscle sensitivity to oxytocin.

OBJECTIVE: We tested the hypothesis that oxytocin (OT) contracts blood vessels via vasopressin V1A (VP) receptors, and that this depends on pregnancy. STUDY DESIGN: Concentration-contraction relationships (CCR) to OT and VP (10(-12)-10(-6) mol/L) were obtained in different blood vessels. CCR were obtained in uterine arteries (UA) from nonpregnant, mid-pregnant, and late pregnant rats (n = 6-10 per group) in the absence and presence of selective antagonists (10(-7) mol/L). RESULTS: Sensitivity to OT, but not to VP, is attenuated in pregnant rat UA. Antagonists shifted CCR of OT and VP to the right, and, to a lesser extent, of the counterpart, in all UA. VP antagonist depresses oxytocin CCR much more than OT antagonist in pregnant rat UA. CONCLUSION: OT and VP contract UA via their own receptors, although partial cross-activation is evident. Adaptation to pregnancy led to attenuated sensitivity of UA smooth muscle to OT and transformed OT receptors into VP-like ones.

Adaptation, Physiological↗
PubMed2006

The effect of dystocia and previous cesarean uterine scar on the tensile properties of the lower uterine segment.

OBJECTIVE: The remodeling of uterine connective tissue during labor can lead to the reorganization of the extracellular matrix that, in turn, may influence the biomechanical properties of the myometrial wall. We hypothesized that the stretching of the lower uterine segment in laboring women with dystocia changes the viscoelastic properties of the uterine wall. STUDY DESIGN: We tested the tensile strength of lower uterine segment myometrium in 68 pregnant women at term. The biomechanical, structural, and biochemical properties were compared among 3 groups: (1) 39 laboring women who underwent primary low-transverse cesarean delivery for labor dystocia, (2) 12 nonlaboring women who underwent primary elective low-transverse cesarean delivery and (3) 17 women who underwent an elective repeat low-transverse cesarean delivery at term. The tensile properties were quantitated with a stretching regimen that was designed to mimic the conditions of labor. Parameters such as slope, yield point, and break point were recorded, analyzed, and interpreted. Biochemical properties were determined by the measurement of the sulfated glycosaminoglycans, hydroxyproline, and pyridinoline-deoxypyridinoline. Histologic properties of the connective tissue were assessed by collagen birefringence. Lastly, the association between these properties and biomechanical responses were compared among groups. RESULTS: Lower uterine segment myometrium specimens obtained from laboring women were stiffer compared with specimens from women who were not in labor (P = .013) or had scarred myometrium (P < .001). The force that was required to reach the yield point was similar between labor and nonlabor groups (P = .216). Likewise, a previous lower uterine segment scar did not alter the yield point. The break point was similar among all groups (P = .317). Sulfated glycosaminoglycan levels were unaffected by labor or scarring (P = .354). Scarred lower uterine segment myometrium had a higher collagen content compared with unscarred myometrium specimens that were obtained during labor (P = .025). Although there were similar degrees of collagen cross-linking among groups (P = .212), there was lower collagen birefringence in myometrium from laboring women compared with nonlaboring women (P < .001). CONCLUSION: Labor alters the viscoelastic properties of myometrium. Lower uterine segment myometrium is stiffest in women with dysfunctional labor compared with nonlabor control subjects. Labor and scarring also alter the pattern of collagen birefringence. Similar collagen cross-linking among the study groups may explain the reason that the breaking strength of the tissue is not altered by the state of labor and the reason that the rupture of the uterine scar is a rare event.

Adult↗
PubMed2006

Is there a nuchal translucency millimeter measurement above which there is no added benefit from first trimester serum screening?

OBJECTIVE: The purpose of this study was to evaluate whether there is a nuchal translucency (NT) measurement, independent of gestational age, above which immediate diagnostic testing should be offered without waiting for first trimester serum markers. STUDY DESIGN: Thirty-six thousand one hundred twenty patients had successful measurement of simple NT at 10 3/7 to 13 6/7 weeks and had first trimester serum screening. No risks were reported until second trimester serum screening was completed. RESULTS: Thirty-two patients (0.09%) had NT > or = 4.0 mm; the lowest combined first trimester trisomy 21 risk assessment in euploid cases was 1 in 8 and among aneuploidy cases was 7 in 8. One hundred twenty-eight patients (0.3%) had simple NT > or = 3.0 mm: the lowest combined first trimester trisomy 21 risk assessment of any patient in this group was 1 in 1479 and the lowest risk assessment among aneuploid cases was 1 in 2. Ten patients (8%) had first trimester trisomy 21 risk assessments lowered to less that 1:200 and none of these 10 cases had an abnormal outcome. CONCLUSION: During first trimester Down syndrome screening, whenever an NT measurement of 3.0 mm or greater is obtained there is minimal benefit in waiting for serum screening results, and no benefit for NT of 4.0 mm or greater. Differentiation between cystic hygroma and enlarged simple NT (> or = 3.0 mm) is now a moot point as both are sufficiently high risk situations to warrant immediate CVS.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed2006

Pharmacokinetics and pharmacotherapy of thionamides in pregnancy.

Hyperthyroidism occurs in approximately 1 in every 1000 to 2000 pregnancies. Although the signs and symptoms of the disease are similar in the pregnant and nonpregnant patient, the complications of hyperthyroidism can have even more profound consequences for the mother and fetus during gestation. These include maternal heart failure, preeclampsia, miscarriage, and preterm labor; as well as fetal loss and low birth weight. Furthermore, thyroid function and laboratory testing for hyperthyroidism are altered in pregnancy. The gestational increase in thyroid size, increased thyroid-binding globulin levels, increased serum total T4 and total T3 levels, and decreased thyroid stimulating hormone levels often confuses the evaluation of the thyroid status in pregnancy. Worldwide, the thionamides-propylthiouracil, methimazole, and carbimazole-have been used in pregnancy for the treatment of hyperthyroidism. However, propylthiouracil has been the drug of choice in the United States because it is believed to have less potential to induce fetal/neonatal hypothyrodism, to cross the placenta and into breast milk to a lesser degree, and to be less teratogenic than methimazole or carbimazole. None of the above have been substantiated in more recent studies. The pharmacokinetics of the thionamides in the pregnant and nonpregnant states, as well as the pharmacotherapeutic recommendation for hyperthyroidism will be reviewed.

Antithyroid Agents↗
PubMed2006

Pregnancy loss rates after midtrimester amniocentesis.

OBJECTIVE: The purpose of this study was to quantify the contemporary procedure-related loss rate after midtrimester amniocentesis using a database generated from patients who were recruited to the First And Second Trimester Evaluation of Risk for Aneuploidy trial. METHODS: A total of 35,003 unselected patients from the general population with viable singleton pregnancies were enrolled in the First And Second Trimester Evaluation of Risk for Aneuploidy trial between 10 3/7 and 13 6/7 weeks gestation and followed up prospectively for complete pregnancy outcome information. Patients who either did (study group, n=3,096) or did not (control group, n=31,907) undergo midtrimester amniocentesis were identified from the database. The rate of fetal loss less than 24 weeks of gestation was compared between the two groups, and multiple logistic regression analysis was used to adjust for potential confounders. RESULTS: The spontaneous fetal loss rate less than 24 weeks of gestation in the study group was 1.0% and was not statistically different from the background 0.94% rate seen in the control group (P=.74, 95% confidence interval -0.26%, 0.49%). The procedure-related loss rate after amniocentesis was 0.06% (1.0% minus the background rate of 0.94%). Women undergoing amniocentesis were 1.1 times more likely to have a spontaneous loss (95% confidence interval 0.7-1.5). CONCLUSION: The procedure-related fetal loss rate after midtrimester amniocentesis performed on patients in a contemporary prospective clinical trial was 0.06%. There was no significant difference in loss rates between those undergoing amniocentesis and those not undergoing amniocentesis. LEVEL OF EVIDENCE: II-2.

Abortion, Spontaneous↗
PubMed2006

Comparison of serum markers in first-trimester down syndrome screening.

OBJECTIVE: To estimate patterns of total hCG and inhibin A levels in the late first trimester of Down syndrome pregnancies, compare them with that of free beta-hCG, and assess screening performance of these markers individually and in combination with pregnancy-associated plasma protein-A (PAPP-A) and nuchal translucency. METHODS: Seventy-nine matched case-control sets of maternal serum samples (each Down syndrome case matched to 5 controls) from 11 through 13 completed weeks of gestation were taken from the sample bank of the First and Second Trimester Evaluation of Risk Consortium, a population-based study, and assayed for levels of free beta-hCG, total hCG, and inhibin A. Distribution characteristics and correlations of the multiples of the median values were estimated in cases and controls. Screening performance for each marker, alone and in combination with PAPP-A, nuchal translucency, and maternal age, was calculated. RESULTS: Median multiples of the median levels of free beta-hCG, total hCG, and inhibin A in cases were more elevated as gestation increased from 11 to 13 weeks, with univariate detection rates of 31%, 23%, and 29%, respectively, at a 5% false-positive rate. At 12 weeks, the multivariate detection rates at a 5% false-positive rate for nuchal translucency and PAPP-A (with maternal age) with either free beta-hCG, total hCG, or inhibin A were 84%, 83%, and 85%, respectively. The improvement in performance from nuchal translucency and PAPP-A to any of the three-marker tests was significant, while performance of any of the three-marker combinations was not significantly different from each other. CONCLUSION: Although levels of free beta-hCG in affected pregnancies were higher earlier than the levels of either total hCG or inhibin A, there was no significant difference in screening performance when either of the three markers was used with nuchal translucency and PAPP-A at 11-13 weeks of pregnancy. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2005

Light-induced fluorescence of the human cervix decreases after prostaglandin application for induction of labor at term.

OBJECTIVE: To define the changes in cervical light-induced fluorescence (LIF), an index of cross-linked collagen, after the use of locally applied prostaglandin preparations for labor induction at term and the correlation between LIF and Bishop-Score. STUDY DESIGN: The characteristic LIF of cervical collagen was measured from the surface of the cervix using a specially designed instrument (collascope) in 41 gravidas undergoing labor induction at term by prostaglandins. LIF and Bishop-Score were obtained directly before and 4h after the administration of prostaglandin. Paired Student's t-test, Wilcoxon Signed Rank test, Linear Regression, Spearman correlation and Fisher Exact test were used as appropriate. RESULTS: Cervical LIF decreased significantly after prostaglandin application (0.982+/-0.04 [before] to 0.885+/-0.037 [after], p=0.025). The decrease in LIF correlated with the initial LIF before PG-application (r=0.61). The Bishop-Score increased in all 41 patients. No correlation was found between LIF versus Bishop-Score. CONCLUSIONS: Cervical application of prostaglandins decreases the amount of cross-linked collagen as measured by LIF. This effect was observed only in patients with a prior high cross-linked collagen.

Administration, Topical↗
PubMed2005

Comparing uterine electromyography activity of antepartum patients versus term labor patients.

OBJECTIVE: The purpose of this study was to compare uterine electromyography of patients delivering>24 hours from measurement with laboring patients<or=24 hours from measurement. STUDY DESIGN: Fifty patients (group 1: labor, n=24; group 2: antepartum, n=26) were monitored using transabdominal electrodes. Group 2 was recorded at several gestations. Uterine electrical "bursts" were analyzed by power-spectrum from 0.34 to 1.00 Hz. Average power density spectrum (PDS) peak frequency for each patient was plotted against gestational age, and compared between group 1 and group 2. Frequency was partitioned into 6 bins, and associated burst histograms compared. RESULTS: Group 1 was significantly higher than group 2 for gestational age (39.87+/-1.08 vs 32.96+/-4.26 weeks) and average PDS peak frequency (0.51+/-0.10 vs 0.40+/-.03 Hz). Histograms were significantly different. A correlation coefficient of .41, with significance, was found with PDS vs gestation. CONCLUSION: Uterine electromyography in antepartum patients is significantly lower than in laboring patients delivering<or=24 hours from measurement.

Adolescent↗
PubMed2005

Sonographic myometrial thickness predicts the latency interval of women with preterm premature rupture of the membranes and oligohydramnios.

OBJECTIVE: Term labor is associated with global thinning of the myometrium. We hypothesized that a thickened myometrium at the time of preterm premature rupture of membranes (PPROM) predicts less myometrial wall stress and, consequently, a longer latency interval. STUDY DESIGN: Myometrial thickness was measured prospectively in 76 pregnant women enrolled in the following groups: PPROM (n=28, mean [range], gestational age [GA]: 29.5 weeks [w] [21.0 w-33.0 w]), preterm nonlabor control group (P-CTR), (n=21, GA: 27.5 w [23.0 w-32.0 w]) and term nonlabor control (T-CTR) (n=27, GA: 38.6 w [37.0 w-41.6 w]). All PPROM women had oligohydramnios (AFI: 1.4 cm [0.0 cm-5.1 cm]). MT was measured ultrasonographically at the midanterior, fundal, posterior, and lower uterine segment wall in cases and controls with an intraoperator variability <10%. RESULTS: Women in the PPROM group displayed uniform thickness of the uterine body (mean +/- SEM, anterior: 10.6 +/- 0.6 mm, fundal: 10.7 +/- 0.7 mm, posterior: 8.9 +/- 0.5 mm, P=.078). At midanterior site the myometrium of the PPROM group was thicker compared to both P-CTR (P < .001) and T-CTR (P=.025) groups. This difference was preserved at the fundus (PPROM vs P-CTR, P < .001; PPROM vs T-CTR, P=.015). There was a positive correlation between fundal MT and latency period (r=0.43, P=0.02) that persisted after adjusting for GA (P=.04). A fundal MT less than 12.1 mm was 93.7% sensitive and 63.6% specific for the identification of women whose latency period was less than 120 hours. CONCLUSION: Significant thickening of the anterior and fundal walls of the uterus follows PPROM. A thick myometrium in nonlaboring patients with PPROM is associated with longer latency interval. Sonographic evaluation of MT may represent an alternative clinical tool for the prediction of a short latency interval in women with PPROM.

Adult↗
PubMed2005

A randomized trial of amnioreduction versus septostomy in the treatment of twin-twin transfusion syndrome.

OBJECTIVE: Left untreated, severe twin-to-twin transfusion syndrome (TTTS) presenting in the early second trimester of pregnancy is often associated with significant maternal morbidity and almost universal perinatal loss. Removal of excessive amounts of amniotic fluid through serial amniocenteses (amnioreduction) has been the mainstay of therapy. We sought to compare amnioreduction to intentional perforation of the intervening twin membrane (septostomy). STUDY DESIGN: Pregnant women with TTTS before 24 weeks' gestation were randomly assigned to serial amnioreduction or septostomy. A single puncture technique under ultrasound guidance was used for the septostomy. The primary outcome measure was survival to neonatal discharge, and was assessed based on the number of pregnancies or the number of fetuses as appropriate. RESULTS: The study was terminated at the planned interim analysis stage after 73 women were enrolled. This was because the rate of survival of at least 1 infant was similar in the amnioreduction group compared to the septostomy group (78% vs 80% of pregnancies, respectively; RR=0.94, 95%CI 0.55-1.61; P=.82). Patient undergoing septostomy were more likely to require a single procedure for treatment (64% vs 46%; P=.04). CONCLUSION: Although overall perinatal survival is not enhanced, septostomy offers the advantage of often requiring a single procedure compared to serial amnioreduction in the treatment of severe twin-to-twin transfusion syndrome.

Amniotic Fluid↗
PubMed2005

Discriminatory proteomic biomarker analysis identifies free hemoglobin in the cerebrospinal fluid of women with severe preeclampsia.

OBJECTIVE: Preeclampsia is an idiopathic multisystem disorder specific to human pregnancy. This study used proteomic analysis of cerebrospinal fluid (CSF) to identify protein biomarkers characteristic of preeclampsia and related to its severity. STUDY DESIGN: CSF was collected from women diagnosed clinically with severe preeclampsia (sPE: n = 7), mild preeclampsia (mPE: n = 8), and normotensive controls (CRL: n = 8). Samples were subjected to proteomic analysis using surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectroscopy. A discriminative proteomic biomarker profile was extracted by applying Mass Restricted analysis, and a Preeclampsia Proteomic Biomarker (PPB) score developed based on the presence or absence of four discriminatory protein peaks in individual CSF SELDI tracings. In-gel tryptic digests, Western blot analysis, on-chip immunoassays, ELISA, and spectral analysis were used to identify the biomarkers composing the PPB score. RESULTS: PPB score distinguished patients with a clinical diagnosis of sPE from mPE and CRLs. (PPB median [range]: sPE: 4 [0-4] vs mPE: 1 [0-1] vs CRL: 0 [0-0]; P < 0.001). PPB scores were unaffected by parity, magnesium seizure prophylaxis, CSF leukocyte counts, and total protein content. Proteomic identification techniques matched the discriminatory protein peaks to the alpha- and beta-hemoglobin chains. ELISA confirmed that women diagnosed clinically with sPE had significantly higher CSF hemoglobin concentrations than women with mPE or CRL (median [range]: sPE: 6.6 [0.0-10.3] microg/mL vs mPE: 0 [0-1.3] microg/mL vs CRL: 0 [0-0] microg/mL; P < 0.001). CONCLUSION: Proteomic analysis of CSF can accurately distinguish sPE from both mPE and CRL. Patients with sPE have nanomolar amounts of free hemoglobin in their CSF. Further studies are needed to confirm these observations and determine their physiologic implications.

Biomarkers↗
PubMed2005

Effect of gestational age and position on peak expiratory flow rate: a longitudinal study.

OBJECTIVE: We sought to study the effects of gestational age and maternal position on peak expiratory flow rates. METHODS: Peak expiratory flow rates were measured in the standing, sitting, and supine positions in 38 healthy pregnant women at 4-week intervals starting at less than 10 weeks until delivery and again at 6 weeks postpartum. The highest reading of 3 consecutive peak expiratory flow rate measurements for each encounter and position was used in the analysis. Repeated measures analysis of covariance was performed with subjects, gestational age, position, and gestational age times position as the model effects. Least squares mean peak expiratory flow rates were compared among positions at different gestation ages using Bonferroni-adjusted least significant difference t tests. RESULTS: Peak expiratory flow rate declined significantly throughout gestation in all positions (P < .001) with mean rate of decline of 0.65 L/min per week). The slopes of linear trends were not statistically different between positions (P = .222). However, the rate of decline for the supine position was higher than for standing and sitting positions (0.86 compared with 0.46 and 0.57 L/min per week), respectively. On average, the postpartum peak expiratory flow rate returned to 71.9% of its measurement in early gestation. Nomograms depicting mean and the 5th and 95th percentiles of peak expiratory flow rates were constructed for each position. CONCLUSION: Peak expiratory flow rate measurements are affected by maternal position and advancing gestational age, especially in the supine position. Adjustment of patient's flow rate in relation to gestational age and maternal position is recommended, especially in pregnant women with asthma. LEVEL OF EVIDENCE: III.

Adult↗