Temporal pattern and spectral complexity as stimulus parameters for eliciting a cardiac orienting reflex in human fetuses.

The purpose of this study was to determine whether temporal pattern and/or spectral complexity were important stimulus parameters for eliciting a cardiac orienting reflex (OR) in low-risk human fetuses. Each of 28 term fetuses was exposed to four sounds formed from the four different combinations of temporal pattern (pulsed, continuous) and spectral complexity (sine wave, /â/). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz, and fetal R-waves were extracted by using adaptive signal-processing techniques. We found that pulsed sounds elicited a significantly greater decrease in heart rate (HR) than did continuous sounds. However, the HR response was relatively unaffected by spectral complexity. For the pure tone and the phoneme used in this study, our results indicate that temporal characteristics were more effective at eliciting a cardiac OR in human fetuses than was spectral complexity.

Human fetuses have nonlinear cardiac dynamics.

Approximate entropy (ApEn) is a statistic that quantifies regularity in time series data, and this parameter has several features that make it attractive for analyzing physiological systems. In this study, ApEn was used to detect nonlinearities in the heart rate (HR) patterns of 12 low-risk human fetuses between 38 and 40 wk of gestation. The fetal cardiac electrical signal was sampled at a rate of 1,024 Hz by using Ag-AgCl electrodes positioned across the mother's abdomen, and fetal R waves were extracted by using adaptive signal processing techniques. To test for nonlinearity, ApEn for the original HR time series was compared with ApEn for three dynamic models: temporally uncorrelated noise, linearly correlated noise, and linearly correlated noise with nonlinear distortion. Each model had the same mean and SD in HR as the original time series, and one model also preserved the Fourier power spectrum. We estimated that noise accounted for 17.2-44.5% of the total between-fetus variance in ApEn. Nevertheless, ApEn for the original time series data still differed significantly from ApEn for the three dynamic models for both group comparisons and individual fetuses. We concluded that the HR time series, in low-risk human fetuses, could not be modeled as temporally uncorrelated noise, linearly correlated noise, or static filtering of linearly correlated noise.

Pneumonia as a complication of pregnancy.

OBJECTIVE: To identify risk factors for the development of antepartum pneumonia and to describe maternal and perinatal outcome in pregnant women with pneumonia. METHODS: The study group consisted of 59 women with antepartum pneumonia. Pneumonia was defined by the presence of lower respiratory tract symptoms, radiographic findings, no other source of infection, and at least two of the following: oral temperature > or =38 degrees C, white blood cell count > or =15,000/ml, auscultatory findings, and/or positive sputum cultures. For comparison, a control group (n = 118) of pregnant women was formed by selecting the first mother who delivered immediately before and after an index study subject. RESULTS: Mothers in the study group were significantly more likely than women in the control group to have either a history of asthma (P = 0.022) or an admission hematocrit < or =30% (P < 0.001). Women with pneumonia were also more likely to receive a tocolytic agent (P < 0.001) and/or beta-methasone to enhance fetal lung maturity (P < 0.001). In addition, study subjects delivered at an earlier mean gestational age (P = 0.002) and had infants who weighed significantly less (P = 0.003) than mothers in the control group. Multivariate analysis indicated that women with asthma or anemia had more than a five-fold increase in the risk of developing pneumonia during pregnancy (P = 0.013), and mothers with pneumonia were significantly more likely to deliver before 34 weeks gestation (P = 0.04). CONCLUSIONS: Pneumonia during pregnancy was associated with maternal anemia and asthma. In addition, preterm labor with tocolysis and/or beta-methasone was more common in women with pneumonia, and these women were more likely to deliver preterm and have low birthweight infants compared to women without pneumonia.

Spontaneous motor activity in the perinatal infant before and after birth: stability in individual differences.

This study was undertaken to determine if a relationship existed between the duration of spontaneous general movements before and after birth. Twenty-two infants were examined three times as fetuses between 38 and 40 weeks gestational age and three times as neonates between 2 and 4 weeks postnatal age. Motor activity level during active sleep periods was quantified by direct sonographic visualization for fetuses and by videotaped images of trunk movement for neonates. We found that both fetuses and neonates exhibited stable individual differences in motor activity level. In addition, infants who moved at a certain rate as fetuses generally moved at the same relative rate as neonates up to 4-weeks postnatal age. Our findings suggested that individual differences in motor activity level in the 1st month following birth probably arise during fetal life.

Behavioral state affects heart rate response to low-intensity sound in human fetuses.

The cardiac orienting reflex is elicited by a low-intensity sound, it consists of a sustained heart rate (HR) deceleration, and it is a specific physiological correlate of cognitive processing. In this study we examined the relationship between behavioral state and the cardiac orienting reflex in 75 human fetuses between 36 and 40 weeks gestation. Each fetus was stimulated with a 30-s speech sound at an average intensity of 83 dB SPL in quiet sleep (QS) and active sleep (AS). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal processing. Fetal behavioral states were assigned based on HR pattern and the presence or absence of eye and general body movements. We found that a significant HR deceleration occurred, in both QS and AS, following stimulus onset. However, HR decelerations occurred more often in QS than AS; and for fetuses exhibiting a HR deceleration, the magnitude of the deceleration was greater in AS compared to QS. In addition, in AS female fetuses exhibited a larger, more sustained HR deceleratory response than male fetuses, but the seconds x gender interaction in QS was not significant. Based on these results, we concluded that behavioral state is an important determinant of the HR deceleratory response in human fetuses.

Hospital readmission for postpartum endometritis.

This study identified risk factors associated with readmission for postpartum endometritis. The study group consisted of 109 mothers (Group I) who were discharged after delivery and readmitted with endometritis. Control groups consisted of women who had endometritis immediately after delivery but who did not require readmission (Group II, n = 109), and women who had no intrapartum or puerperal infection and also were not readmitted (Group III, n = 109). Subjects in Groups II and III were matched to an index study subject for date of delivery and maternal age, race, and parity; and women in Groups I and III were also matched for route of delivery. Groups were compared in terms of demographic characteristics, intrapartum course, and clinical presentation. The data were analyzed with the t-test, chi2, and multiple logistic regression analyses, and a P value < .05 was considered significant. Women in Groups I and III delivered vaginally more often than mothers in Group II. In addition, mothers in Groups I and III had similar postpartum courses, no evidence of infection on discharge after delivery, and a similar period from delivery until postpartum discharge. Although women in Group I were more likely to have spontaneous rupture of membranes, a shorter latent period, and have fewer bilateral tubal ligations than mothers in Group II, multivariate analysis identified route of delivery as the only significant maternal variable associated with postpartum endometritis requiring readmission. Women who were readmitted for endometritis usually delivered vaginally, and the occurrence of late-onset postpartum endometritis was unrelated to the length of stay following delivery.

Pregnancy in women with spinal cord injuries.

Most women with spinal cord injuries (SCI) resume normal reproductive function, can have sexual relationships, and become pregnant. Pregnancy is not contraindicated in women with SCI, but pregnant women with acute or chronic SCI pose unique challenges for perinatal health care providers. The normal physiologic changes of pregnancy may predispose women with SCI to potentially life-threatening complications, including autonomic hyperreflexia, pyelonephritis, respiratory insufficiency, thrombophlebitis, and unattended delivery of the infant. This article reviews the effect of SCI on female reproduction, pregnancy, and labor, and summarizes the treatment of the pregnant woman with a spinal cord injury.

Methods used to diagnose premature rupture of membranes: a national survey of 812 obstetric nurses.

OBJECTIVE: To identify methods used to diagnose premature rupture of membranes (PROM). METHODS: A 14-item questionnaire was mailed to 1992 registered nurses certified in inpatient obstetrics to determine information on practice facility, obstetric services, procedures used to obtain vaginal fluids for testing, and methods used to diagnose PROM. RESULTS: A total of 812 (40.8%) surveys were available for analysis. Of tests used to confirm PROM, observation of pooling fluid in the posterior fornix and fern tests were much more likely to be used in teaching and military hospitals and in facilities with tertiary obstetric services than in private hospitals (all P values < .001). To obtain vaginal fluids for fern and nitrazine testing, the dry glove method (ie, insertion of a gloved hand or nitrazine strip into the vagina) was used significantly more often in private hospitals than in teaching or military facilities (P < .001). In addition, the dry glove method was used significantly more often (P < .001) and the speculum examination was used less often (P < .001) to collect vaginal fluids for testing when private physicians performed more than 75% of deliveries at a particular hospital. In contrast, vaginal fluid was obtained during a sterile speculum examination more often in facilities in which more than 75% of deliveries were performed by residents (P < .001), and/or when more than 75% of speculum examinations were performed by nursing personnel (P < .001). Multiple linear regression analyses indicated that observation of pooling fluid and use of the fern test were significantly associated with hospital type, percentage of deliveries by private physicians, and percentage of speculum examinations performed by nursing personnel (all P values < .001). CONCLUSION: A sterile speculum examination is used more often to obtain vaginal fluids for testing and to diagnose ruptured membranes in teaching or military facilities and when nursing personnel have been trained in speculum examinations.

Clinical presentation of women readmitted with postpartum severe preeclampsia or eclampsia.

OBJECTIVE: To identify symptoms that prompted a group of women readmitted for postpartum severe preeclampsia or eclampsia to seek medical care. DESIGN: Retrospective, case-control. SETTING: Tertiary-care teaching hospital. SUBJECTS: The study group consisted of 53 women readmitted in the postpartum period with severe preeclampsia or eclampsia. The control group was matched two-to-one with an index study participant and consisted of 106 women who had intrapartum severe preeclampsia or eclampsia. MAIN OUTCOME MEASURES: Patient symptoms, physical findings, laboratory assays. RESULTS: Neurologic complaints, malaise, and nausea and vomiting were reported more often in women who were readmitted than in mothers with intrapartum preeclampsia (all p values less than .001). Headaches were positively correlated with systolic, diastolic, and mean arterial blood pressure in women who were readmitted (all p values less than .05), although there was no relationship between blood pressure and headaches in the control group. In addition, multivariate analysis revealed that study participants were more likely to deliver at full term, have headaches and malaise, have normal platelet values, and develop seizures than mothers in the control group, chi 2 = 155.7, p < .001. CONCLUSIONS: Women readmitted for postpartum severe preeclampsia or eclampsia have a clinical presentation that differs from that of intrapartum preeclampsia or eclampsia.

The antiphospholipid antibody syndrome: an overview.

The antiphospholipid antibody syndrome is characterized by the presence of maternal anticardiolipin antibodies and/or the lupus anticoagulant in association with recurrent pregnancy loss, thrombotic events, and/or thrombocytopenia. This disorder occurs rarely, but pregnant patients with antiphospholipid antibodies are at risk for adverse maternal and perinatal outcomes. This article reviews the antiphospholipid antibody syndrome, including its pathophysiology, clinical sequelae, diagnostic criteria, medical treatment, and nursing care.

Temporal stability in the distribution of behavioral states for individual human fetuses.

Although behavioral state analyses have been useful in differentiating between groups of normal and at-risk fetuses, the large between-subject differences in the percent time spent in the various behavioral states poses a major obstacle in identifying abnormal neurological functioning in individual fetuses. Does this variability represent a true difference in state organization between fetuses, or does it simply reflect individual fluctuations in state control at the time of observation? To answer this question, we examined each of 33 human fetuses for 4 h on three separate days between 38 and 40 weeks gestation. The percent time spent in each behavioral state and in transition and insertion periods was determined for each of the three 4-h study sessions, and within-subject analysis of variance was performed to obtain an objective measure of state profile consistency for each fetus. We found that, on the average, fetuses exhibited remarkable within-subject consistency in their state profiles. However, even among this group of low-risk fetuses, there were significant differences in the degree of state organization achieved by individual fetuses. These findings, which indicate the existence of a well-developed central nervous system before birth, suggest that individual differences in the consistency of behavioral state profiles may be indexing important between-subject differences in neurological development.

The heart rate deceleratory response in low-risk human fetuses: effect of stimulus intensity on response topography.

The purpose of this study was to determine the effect of stimulus intensity on heart rate response in 18 low-risk human fetuses between 37 and 40 weeks gestation. Each fetus was stimulated in quiet sleep with a 30-s voice sound at intensities of 80 dB and 90 dB. The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal-processing techniques. We found that fetuses generally exhibited a 5- to 10-s decrease in heart rate following stimulus onset at an intensity of 80 dB. The response pattern changed from deceleratory to acceleratory when stimulus intensity was increased to 90 dB. Our findings suggest that a heart rate deceleration at low-stimulus intensity may be a component of the orienting reflex in the human fetus.

Similarities and differences in behavioral state organization during sleep periods in the perinatal infant before and after birth.

The purpose of this study was to determine the degree of consistency in behavioral state organization for 30 low-risk human participants examined as fetuses at 38-40 weeks gestation and again as neonates at approximately 2 weeks postnatal age. Behavioral states were assigned similarly for fetuses and neonates in terms of heart rate pattern and the presence or absence of eye and gross body movements. We found that the time spent in a sleep period was distributed among quiet sleep (QS), active sleep (AS), and indeterminate states in virtually identical proportions for fetuses and neonates. However, the only within-subject consistency between the fetal and neonatal periods was in the duration of complete QS epochs. Fetuses made fewer transitions between QS and AS, but neonates had shorter and more structured AS-->QS transitions. These findings suggest that, whereas central nervous system processes governing QS do not change appreciably, the control of AS undergoes significant changes in the 4 weeks spanning the fetal and neonatal periods. We believe that the duration of enclosed QS epochs provides the only stable measure of behavioral state development between the prenatal and postnatal periods.

Elevated midtrimester mean arterial blood pressure in women with severe preeclampsia.

Although early identification of pregnant women who are at risk for severe preeclampsia may help reduce maternal-perinatal sequelae, an adequate screening test for this disorder has not been described. The purpose of this study was to determine if a group of women (n = 57) who developed severe preeclampsia had a higher midtrimester mean arterial pressure (MAP-2) than a matched group of women (n = 57) who remained normotensive throughout pregnancy and the puerperium. It was found that women who developed severe preeclampsia had a significantly higher MAP-2 than normotensive women and significantly more preeclamptic subjects had an MAP-2 > or = 85 mmHg than did control subjects. Thus, an elevated MAP-2 may help identify women who are at risk for the development of severe preeclampsia.

Blood pressure changes in normotensive women readmitted in the postpartum period with severe preeclampsia/eclampsia.

The purpose of this study was to determine whether women who had no clinical evidence of preeclampsia at delivery, but who were later readmitted with postpartum severe preeclampsia or eclampsia, differed in mean arterial pressure (MAP) and clinical presentation from women who either remained normotensive or had severe preeclampsia or eclampsia at the time of delivery. Control subjects did not require readmission and were matched (2:1) with study subjects in consecutive order for date of delivery and maternal age, race, and parity. Women in the study group had a significantly greater increase in MAP after delivery than control subjects, and analysis of variance for linear trends demonstrated highly significant differences between the study and control groups in the average intrapartum and postpartum MAPs. Compared to women in either control group, mothers who were readmitted were significantly more likely to demonstrate a > 10-mm Hg increase in MAP between the intrapartum and postpartum periods (delta MAP). Normotensive women with a delta MAP > 10 mm Hg had more than a threefold risk of readmission in the postpartum period with severe preeclampsia or eclampsia. Women who were readmitted reported a significantly greater frequency of headaches and nausea and vomiting than women with intrapartum preeclampsia. In summary, our findings indicate that MAP increase following delivery in normotensive women who were later readmitted with severe preeclampsia or eclampsia.

Reproductive risks of cocaine.

Cocaine use during pregnancy in the USA has increased dramatically in the past decade, and has resulted in an associated increase in a variety of maternal and perinatal complications. However, a number of confounding factors make it difficult to determine the direct impact of perinatal cocaine use on maternal and fetal outcome. Many substance-abusing women use multiple drugs while pregnant, receive inadequate prenatal care and are predisposed to other health problems that impact on perinatal outcome. As a result of the rapid clearance of cocaine and limitations of available screening methods, the identification of individual users can be difficult. Furthermore, the determination of accurate prevalence rates of cocaine use during pregnancy has been frustrated by sampling bias. Cocaine has profound systemic and cardiovascular effects in both the mother and the fetus, and as a result a number of complications (i.e. fetal malformations, preterm labour, placental abruption) have been attributed to perinatal cocaine exposure. In addition, maternal cocaine use has been associated with a number of neonatal abnormalities, including cardiopulmonary effects, somatic changes and neurobehavioural sequelae. It is estimated that US $500 million dollars in additional health expenditure resulted from increased neonatal hospital costs and longer lengths of stay for cocaine-exposed neonates. This article reviews the reproductive risks associated with prenatal cocaine use. The pharmacology and physiology of cocaine in relation to pregnancy is discussed, and the impact of this substance on the growth and development of the fetus and infant is reviewed.

Maternal anxiety during pregnancy: effect on fetal behavior at 38 to 40 weeks of gestation.

The purpose of this study was to determine if there is a relationship between fetal behavior and maternal anxiety during pregnancy. The study population consisted of 18 uncomplicated human pregnancies at 38 to 40 weeks gestation. Maternal anxiety was assessed one time using Spielberger's State-Trait Anxiety Inventory. After an overnight fast, each mother was given a standard meal on arrival to the fetal testing unit. Each fetus was examined for 4 hours using heart rate monitoring and real-time sonography. Fetal behavioral states were assigned based on heart rate pattern and the presence or absence of eye and gross body movements. We found that, compared with fetuses of mothers with low trait anxiety scores, fetuses of mothers with relatively high trait anxiety scores spent significantly more time in quiet sleep and exhibited less gross body movement when in active sleep. The results of this pilot study raise the possibility that maternal anxiety during pregnancy may have a significant effect on fetal behavior.