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Biomedical subjects

M Porto

Publications and source records attributed to M Porto.

At least 37 records · Page 2Linked to original sources
PubMed1997

Maternal stress, HPA activity, and fetal/infant outcome.

Preliminary conclusions from our research include the possibility that each of the HPA products evaluated, even though correlated (e.g., ACTH and beta E), may be linked to unique and specific outcomes. Maternal stress during the 28-30 weeks of gestation is associated with birth outcome. Increased levels of psychosocial stress were significantly related to gestational age at birth and infant birth weight. Maternal stress during the third trimester was associated with increased maternal plasma levels of ACTH and cortisol. This finding is consistent with possible mechanisms whereby psychosocial stress influences birth outcome. CRH controls the timing of labor and delivery. Precocious elevation of CRH is related to the risk of preterm delivery. This system may be "stress-sensitive." Even though pregnant women may be immunized from stress, the stress signal that is transmitted (release of ACTH and cortisol) is amplified by the placental release of CRH. This possibility has at least two consequences: (1) influencing the timing of delivery and (2) desensitization of hypophyseal corticotrophs and further "protection" of the pregnant women from the results of stress (i.e., release of ACTH and beta E). Beta E appears to influence fetal learning and perhaps the developing nervous system.

Adrenocorticotropic Hormone↗
PubMed1997

Human fetal heart rate dishabituation between thirty and thirty-two weeks gestation.

Few studies of human fetal habituation have included dishabituation procedures (i.e., assessment of the reemergence of a habituated response) to determine if response decrements are the result of reevaluation of information (a brain process) or fatigue of peripheral receptors. The purpose of this study is to describe the ability of the human fetus to learn and recall information with procedures to assess the central nervous system. Fetal heart rate (FHR) of 84 fetuses between 30 and 32 weeks gestational age was examined in response to 3 series of vibroacoustic (VA) stimuli presented at pseudorandom intervals of 25-45 s over the head of the fetus. Responses to the first series of 15 stimuli (S1) were compared with an identical second series of 15 stimuli (S1) presented over the head of the fetus. Between the 2 series, a novel (dishabituating) VA stimulus (S2) was presented, differing from S1 in intensity and frequency. The third series of S1s was applied to the mother's thigh as a control for possible maternal responses to the stimulus. Prestimulus FHR was computed during a 5 s interval before each stimulus, and mean FHR was computed during the intertrial interval (average FHR). The response to S1 during the first series of trials (1-15) produced a sustained rise in both prestimulus and average FHR, r(83) = .90, p < .001. After the novel S2 (trial 16) the rate of change was attenuated for average FHR, r(83) = .12, ns, to S1 for trials 17-31 but not prestimulus FHR, r(83) = .50, p < .001. The decrease in FHR response was reestablished when stimulation was applied to mother's thigh, trials 32-41, r(83) = .92, p < .001. A significant habituation pattern across trials was observed for the first series of S1s when prestimulus HR was subtracted from each preceding average FHR value (delta FHR). After the single novel stimulus (S2), the FHR response to S1 reemerged. All combinations of beginning and ending series slopes were compared, and only the rate of change during the last 4 trials of the initial presentation of S1 and the first 4 trials after the novel stimulus was significant, F(1, 82) = 9.21, p < .003. Uterine contractions collected from the continuous record were not related to the presentation of the novel stimulus, chi 2(1, N = 84) = 0.59, p < .50, ns, or delta FHR slope after the novel stimulus, chi 2(9, N = 84) = 10.52, p < .50, ns. These results established that the 32 week human fetus is capable of detecting, habituating, and dishabituating to an external stimulus and support the premise that areas of the human fetal central nervous system critical for detecting and discriminating information and for learning and memory have developed by the early third trimester.

Arousal↗
PubMed1996

Sonographic prediction of shoulder dystocia in infants of diabetic mothers.

OBJECTIVE: To determine if the difference between the abdominal diameter and biparietal diameter (AD-BPD difference), as measured by ultrasound examination, predicts shoulder dystocia in borderline macrosomic infants of diabetic mothers. METHODS: A retrospective study was performed of births occurring from January 1990 through June 1995. Eligibility requirements included diabetic pregnancy, ultrasound examination within 2 weeks of delivery, estimated fetal weight of 3800-4200 g, and vaginal delivery. The mean AD-BPD difference was compared in normal deliveries and those complicated by shoulder dystocia, using the Student t test and by multiple regression analysis. A receiver operating characteristic curve was generated to determine if an AD-BPD cutoff value could be used clinically to predict shoulder dystocia. RESULTS: Thirty-one patients, six with dystocia, were eligible for the study. The mean AD-BPD differences for those with and without shoulder dystocia were 3.1 and 2.6 cm, respectively, a statistically significant difference (P = .05). Comparing the groups with and without shoulder dystocia, no significant differences could be found in mean age, parity, weight, birth weight, or gestational age. Shoulder dystocia occurred in six of 20 patients (30%) in whom the AD-BPD difference was at least 2.6 cm but in none of 11 patients in whom it was less than 2.6 cm, also a statistically significant difference (P = .05). CONCLUSION: The AD-BPD difference was greater in borderline macrosomic fetuses of diabetic mothers who experienced shoulder dystocia than in those who had uncomplicated vaginal deliveries. Applying an AD-BPD cutoff value of 2.6 cm to this population prospectively would have provided excellent sensitivity, specificity, and predictive value in identifying those fetuses at high risk for birth injury.

Adult↗
PubMed1995

Third trimester POMC disregulation predicts use of anesthesia at vaginal delivery.

In a prospective study, third trimester plasma levels of BE and ACTH were determined in 58 women who delivered vaginally. Peptide regulation was compared between subjects who used conduction anesthesia at delivery and subjects who did not. Third trimester levels of maternal BE and ACTH were significantly related; however, the relationship was significant only in subjects who did not receive conduction anesthesia (n = 24) at delivery. The normal co-release pattern between BE and ACTH in subjects receiving conduction anesthesia (n = 34) during birth was uncoupled. The use of conduction analgesia during vaginal delivery was significantly related to a disregulation index created to quantify the BE-ACTH release pattern. Uncoupled ACTH and BE patterns may result from modified control of pro-opiomelanocortin (POMC) expression during pregnancy or unique proteolytic processing of POMC, and may alter pain tolerance during delivery.

Adolescent↗
PubMed1995

Biometry of the fetal cisterna magna: estimates of the ability to detect trisomy 18.

Measurements of the fetal cisterna magna were obtained from a prospective sample of patients undergoing diagnostic obstetric ultrasound examinations. These normal measurements were then compared to a retrospective sample of ultrasound scans from fetuses with the diagnosis of trisomy 18 by amniocentesis. The fetal cisterna magna increases in size throughout pregnancy. The sample from fetuses with trisomy 18 was different and had a higher rate of small and large cisterna magnas. After the two samples were mixed, it was determined that a cut-off of 2.5 standard deviations for the fetal cisterna magna would give a sensitivity of 26.3%, specificity of 99.1%, positive predictive value of 50.0% and negative predictive value of 97.6% for trisomy 18. The probability that a fetal cisterna magna of abnormal size will predict trisomy 18 in an early second-trimester ultrasound examination with the 2.5 standard deviation cut-off was estimated at 0.019. A fetal cisterna magna that is of abnormal size appears to be of diagnostic value in identifying the fetus with trisomy 18, but its sensitivity is low.

Adult↗
PubMed1995

Evaluation of the nonreactive positive contraction stress test prior to 32 weeks: the role of the biophysical profile.

A nonreactive positive contraction stress test in a pregnancy near term is an indication for delivery. Such nonreassuring antepartum testing combined with severe prematurity presents a management dilemma. Ideally, prolongation of selected pregnancies would allow time for corticosteroid therapy and fetal maturation. Prior to 32 weeks' gestation, we utilized the biophysical profile to select patients for continued intrauterine management as an alternative to immediate delivery. Continued surveillance was undertaken if the fetus had a reassuring biophysical profile score; immediate delivery by cesarean section was undertaken if the biophysical profile score was nonreassuring. This approach allowed a mean gain of 13 days in utero for the continued surveillance group. There was no evidence of further fetal compromise in this group based on umbilical cord pH or 5-minute Apgar scores. These data suggest that the biophysical profile can be safely used to prolong selected preterm pregnancies with nonreactive positive contraction stress tests without adversely affecting the initial neonatal metabolic status.

Adult↗
PubMed1995

Tocolysis in advanced preterm labor: impact on neonatal outcome.

Chart review of 73 patients with 3.5 cm or more dilation, intact membranes, and regular contractions at less than 36 weeks. Forty-four (group A) received tocolysis with magnesium sulfate, and 13 of the 44 also received indomethacin. Twenty-nine (group B) received no tocolysis. Obstetric and neonatal outcomes were compared. Demographic factors and admission gestational age, cervical dilation, effacement, and uterine activity were similar. Twenty-one of the 44 in group A versus 3 of 29 in group B had delivery delayed by more than 48 hours (p = 0.002). Group A had a lower incidence of severe respiratory distress syndrome; 4 of 48 babies in group A versus 9 of 32 in group B (p = 0.04; RR = 0.47; confidence interval [CI], 0.2, 1.0). Tocolysis in advanced preterm labor delays delivery by more than 48 hours in 50% of patients. The neonatal benefits of aggressive tocolysis in cases with advanced cervical dilation may outweigh the potential maternal risks of tocolysis, particularly in the setting of extreme prematurity. Delay in delivery enabling steroid enhancement of pulmonary maturity reduces the severity of respiratory distress syndrome.

Cohort Studies↗
PubMed1994

Prediction of an abnormal karyotype in fetuses with omphalocele.

The aim of this study was to assess the value of ultrasonographic evaluation in predicting abnormal karyotypes in fetuses with omphalocele. Forty fetuses with antenatally diagnosed omphalocele and available karyotype results were reviewed. Ultrasound evaluation included herniation contents and size, and the detection of other anomalies. Nine of 40 consecutive fetuses had abnormal karyotypes: trisomy 18 (n = 5), trisomy 13 (n = 3), 47,XXX (n = 1). Only 1/25 with an extracorporeal liver versus 8/15 with an intracorporeal liver had abnormal chromosomes [P = 0.0006, RR = 0.14 (0.02 < RR < 0.9)]. Small defects (< 3 cm) were associated with abnormal karyotypes [P = 0.01, RR = 4.7 (1.4 < RR < 15.6)]. Finding concurrent malformations was highly associated with chromosomal anomalies [P = 0.00004, RR = 4.4 (2.3 < RR < 8.5)]. The presence of associated malformations, an intracorporeal liver, and a small herniation size are highly suggestive of an associated abnormal karyotype.

Chromosome Aberrations↗
PubMed1994

Experimentally induced intermittent sinusoidal heart rate pattern and sleep cycle in fetal lambs.

OBJECTIVE: Intermittent sinusoidal heart rate pattern, an early indicator of fetal anemia, has been speculated to have a positive correlation with fetal sleep cycles. To test this hypothesis, intermittent sinusoidal heart rate patterns were produced experimentally with arginine vasopressin in six methylatropinized fetal lambs that were demonstrating clear rapid-eye-movement and non-rapid-eye-movement sleep cycling. STUDY DESIGN: Eleven trials of arginine vasopressin infusion (40 to 160 mIU per body per minute) were performed on each of six chronically instrumented fetal lambs subsequent to parasympathetic blocking doses of methylatropine (300 to 400 micrograms). An intermittent sinusoidal heart rate pattern was observed in relation to fetal sleep cycles. RESULTS: Alteration between rapid-eye-movement and non-rapid-eye-movement sleep was observed in methylatropinized fetuses. In the six fetuses that showed intermittent sinusoidal heart rate patterns subsequent to arginine vasopressin infusion, the fetal heart rate tracing and fetal electrocorticogram demonstrated alternate sinusoidal pattern and reactive heart rate patterns during high- and low-voltage electrocorticogram activity, respectively. CONCLUSION: These findings support the hypothesis that fetal sleep cycling has a positive correlation with the periodic appearance of intermittent sinusoidal heart rate patterns.

Animals↗
PubMed1993

Fetal choroid plexus cysts: an independent risk factor for chromosomal anomalies.

As a result of numerous conflicting reports, we designed a prospective controlled study to determine the inherent risk of aneuploidy with second-trimester fetal choroid plexus cysts. Our controls were patients who had ultrasonography and genetic amniocentesis, between 15 weeks and 22 weeks, menstrual age, by the same sonologist on the same day as a study subject with a choroid plexus cyst. Sixty-three cases of fetal choroid plexus cysts were detected in 3247 second-trimester examinations (1.9%). Six chromosomally abnormal fetuses [Trisomy 18 (3), Down syndrome (2), Klinefelter syndrome] were found in the cyst group (9.5%) with only one Trisomy 21 among the controls (0.5%) (p < .002). Of note, 5 of 21 (23.8%) fetuses with cysts greater than 5 mm in diameter had aneuploidy, as compared with only 1 of 42 (2.4%) chromosomal anomalies with smaller cysts (p < .02). We conclude that fetal choroid plexus cysts are an independent risk factor for chromosomal anomalies; genetic counseling and prenatal chromosomal analysis are indicated.

Adult↗
PubMed1993

The association between prenatal stress and infant birth weight and gestational age at birth: a prospective investigation.

OBJECTIVE: The aim was to test a model of the influence of maternal prenatal psychosocial stress on birth outcomes after controlling for biomedical risk. STUDY DESIGN: In a prospective study a sociodemographically homogeneous sample of 90 women was assessed during the third trimester with standard, reliable questionnaires that measured episodic and chronic stress, strain (response to stress), and pregnancy-related anxiety. Birth outcomes included infant birth weight, gestational age at birth, and intrapartum complications. Parity and biomedical (antepartum) risk was also coded. Bivariate and multivariate analyses were performed after controlling for the effects of biomedical risk factors. RESULTS: Independent of biomedical risk, each unit increase of prenatal life event stress (from a possible sample range of 14.7 units) was associated with a 55.03 gm decrease in infant birth weight and with a significant increase in the likelihood of low birth weight (odds ratio 1.32), and each unit increase of prenatal pregnancy anxiety (from a possible sample range of 5 units) was associated with a 3-day decrease in gestational age at birth. CONCLUSION: Independent of biomedical risk, maternal prenatal stress factors are significantly associated with infant birth weight and with gestational age at birth.

Adult↗
PubMed1993

Intermittent sinusoidal heart rate pattern in vagotomized fetal lambs.

OBJECTIVES: Our aims were to investigate the relationship between the dose of arginine vasopressin and the pattern and duration of arginine vasopressin-induced sinusoidal fetal heart rate and to elucidate the correlation between intermittent sinusoidal heart rate and fetal sleep cycle. STUDY DESIGN: Sinusoidal heart rate pattern was induced by intravenous arginine vasopressin infusion at doses from 2 to 78 mlU/min into 11 chronically instrumented fetal lambs with bilateral cervical vagotomy. Appearance and frequency of sinusoidal heart rate, intermittent sinusoidal heart rate, and persistent sinusoidal heart rate were observed along with fetal tracheal pressure and electrooculogram. RESULTS: Intermittent sinusoidal heart rate response to low, medium, and high doses of arginine vasopressin appeared in 73.3%, 50.0%, and 33.3% of experiments, respectively. Intermittent sinusoidal heart rate appeared more frequently than persistent sinusoidal heart rate with lower doses (p < 0.02). When intermittent sinusoidal heart rate was induced, the incidence of sinusoidal patterns significantly increased during non-rapid-eye-movement sleep in comparison with rapid-eye-movement sleep (p < 0.01). CONCLUSIONS: Appearance of sinusoidal heart rate seems to be related to the dose of arginine vasopressin infused. Appearance of sinusoidal heart rate is also influenced by fetal sleep cycle; sinusoidal heart rate is more likely to appear during non-rapid-eye-movement sleep than during rapid-eye-movement sleep. These results support the hypothesis that persistent sinusoidal heart rate correlates with severity of stress.

Animals↗
PubMed1993

The influence of elective amniotomy on fetal heart rate patterns and the course of labor in term patients: a randomized study.

OBJECTIVES: Our study was designed to evaluate the effects of routine elective amniotomy on the frequency and severity of abnormal fetal heart rate patterns and on the course of labor and the need for oxytocin augmentation. STUDY DESIGN: A randomized, controlled trial was conducted at term in patients in active labor who were randomly selected to undergo elective amniotomy (amniotomy group) or left intact with amniotomy reserved for specific indications (intact group). RESULTS: Four hundred fifty-nine patients were studied (235 in the amniotomy group vs 224 in the intact group). Average cervical dilatation at rupture was 5.5 cm in the amniotomy group and 8.1 cm in the intact group. Analysis of fetal heart rate revealed more mild and moderate variable decelerations in the active phase of labor in the amniotomy group but no difference in the frequency of more severe decelerations or operative deliveries. In the intact group the need for oxytocin was twice as common (76 in the intact group vs 36 in the amniotomy group, p = 0.000005), and the active phase of labor was considerably longer (5 hours 56 minutes in the intact group vs 4 hours 35 minutes in the amniotomy group). Neonatal outcome was similar in the two groups. CONCLUSIONS: Elective amniotomy appears to increase the likelihood of umbilical cord compression in the active phase of labor and results in more mild and moderate variable decelerations, but it does not result in more severe abnormal fetal heart rate patterns or more operative intervention. Elective amniotomy does, however, shorten the active phase of labor and decreases the need for oxytocin augmentation.

Amnion↗
PubMed1993

Cocaine intoxication presenting as preeclampsia and eclampsia.

OBJECTIVE: To relate the clinical presentation of acute cocaine intoxication in the third trimester to preeclampsia and eclampsia. METHODS: Eleven women presented to Long Beach Memorial Women's Hospital and the University of California, Irvine Medical Center with hypertension and clinical symptoms of headache, blurred vision, abdominal pain, or seizures in the third trimester of pregnancy. Each had a positive urine drug screen for cocaine. The laboratory evaluation for preeclampsia included a complete blood count, platelet count, uric acid, aspartate aminotransferase, alanine aminotransferase, creatinine, and urine for protein content. RESULTS: All women had a diastolic blood pressure of at least 90 mmHg, which returned to the normal range 45-90 minutes after admission. Each presented with one or more symptoms associated with preeclampsia, which ultimately improved as the drug wore off. In addition, all laboratory evaluations for preeclampsia were negative. CONCLUSION: If a patient presents in the third trimester with hypertension and clinical symptoms of preeclampsia that rapidly improve shortly after admission, cocaine intoxication should be considered as the possible source.

Cocaine↗