The clinical significance of pain and cognitive activity in latent labor.

We examined the relationship between pain and cognitive activity during the latent (less than or equal to 3 cm), mid-active (5-7 cm), and transition (greater than or equal to 8 cm) phases of labor and the concomitant efficiency of the latent, active, and descent phases in 115 nulliparous women. Patients provided subjective pain ratings and described their thoughts during each of the three phases. Higher levels of pain during the latent phase of labor were predictive of longer latent (r = 0.58) and active (r = 0.50) phases of labor. Distress-related thoughts during latent labor were predictive of longer latent (r = 0.31, P less than .01), active (r = 0.67), and second-stage (r = 0.61) labor. We found no relationships between pain and cognitive activity measured during active labor and efficiency of active labor or second stage of labor. Pain and cognitive activity assessed during the latent phase were also prognostic of obstetric outcome. Thirteen of 19 women (68.4%) who reported "horrible" or "excruciating" pain required instrumental delivery, compared with eight of 27 women (29.6%) in the "discomforting" pain group. Subjects in the "distress-related" cognitive group had 2.6 times the incidence of instrumental delivery, five times the incidence of abnormal fetal heart rate patterns, and four times the requirement for pediatric assistance for the neonate than subjects in the "coping" group. We conclude that latent labor is a critical phase in the psychobiology of labor and that pain and cognitive activity during this phase are important contributors to labor efficiency and obstetric outcome.

Uteroplacental blood flow in the hypertensive, term pregnant, spontaneously hypertensive rat.

Carbohydrate overfeeding throughout pregnancy prevents the progressive fall in blood pressure to normotensive levels during the last week of gestation in the spontaneously hypertensive rat. Cardiac output, organ blood flows, and vascular resistances, measured with radioactive-labeled microspheres, were compared in three groups: carbohydrate-supplemented (hypertensive) term-pregnant rats, control-fed (normotensive) term-pregnant rats, and control-fed (hypertensive) nonpregnant rats. Blood pressure remained elevated in the carbohydrate-supplemented pregnant rats because the normal decrease in total peripheral resistance did not occur. There were no significant differences in organ blood flows between hypertensive and normotensive pregnant rats, with the exception of a 26% lower placental blood flow in the hypertensive versus the normotensive rats. Carbohydrate overfeeding was associated with reduced litter size but did not affect fetal growth. Both placental blood flow and litter size were inversely related to mean arterial blood pressure at term. This may be a useful model of essential hypertension during pregnancy.

Preterm premature rupture of the membranes with fetal pulmonary maturity present: a prospective study.

Ninety-nine patients with premature rupture of the membranes (PROM) before 36 weeks' gestation and documented fetal pulmonary maturity were studied prospectively. Fifty-two patients in labor were allowed to deliver. The remaining 47 were randomly assigned to either prompt delivery (N = 26) or conservative management (N = 21). The overall corrected perinatal survival was excellent (96%). Only one death in the entire series clearly was due to prematurity. Expectant management prolonged gestation greater than one week in only four of 21 patients (19%), and was associated with a significantly increased risk of maternal infections. There were no failed inductions of labor, and 22 of 24 induced patients (92%) delivered vaginally. Neonatal morbidity was similar in each group. These findings in an indigent, largely black population suggest that when pulmonary maturity is present, the maternal risks of conservative management may exceed the potential benefit to the fetus and newborn. The findings of this study may be specific to the population studied, and extrapolation to dissimilar populations may not be warranted.

The effect of hydralazine on placental perfusion in the spontaneously hypertensive rat.

Intravenous hydralazine was administered to 16 spontaneously hypertensive rats on day 21 of gestation. The radioactive labeled microsphere technique was used to assess the change in organ perfusion produced by the drug. Vascular resistance to most organs was decreased, except to the placentas, stomach, and cecum, where it increased by 43%, 104%, and 44%, respectively. Blood flow to the organs was redistributed, and although it was increased to the lungs, kidneys, liver, and adrenals, it was significantly reduced to the spleen, stomach, placentas, cecum, large intestine, and pancreas. The effect of hydralazine on placental perfusion was opposite to the effect on the uterus (myometrium). Patients with the highest blood pressures tend to have the poorest placental perfusion. Intravenous hydralazine should be used cautiously in these patients.

The effect of carbohydrate overfeeding on blood pressure in the pregnant, spontaneously hypertensive rat.

Carbohydrate overfeeding increases blood pressure in the spontaneously hypertensive rat. This study was undertaken to determine if dietary carbohydrate supplementation throughout pregnancy could prevent the normal fall in blood pressure during the last week of gestation. Systolic blood pressure in the control-fed pregnant rats decreased progressively during the last week and was in the normotensive range by term; that of the carbohydrate-supplemented, pregnant rats remained high and was not significantly lower than that of nonpregnant rats at any time. At term, daily urinary norepinephrine excretion, but not epinephrine excretion, by the carbohydrate-supplemented pregnant rats was twice that of control-fed nonpregnant and pregnant rats, suggesting that the hypertension was due to increased sympathetic nervous activity. Carbohydrate supplementation had no effect on blood pressure or catecholamine excretion in pregnant, normotensive Wistar-Kyoto rats. There were no differences in litter size or mean birth weight between diet treatment groups of either strain.

Hexoprenaline tocolysis for intrapartum fetal distress and acidosis.

Hexoprenaline, a selective beta 2-sympathomimetic drug, was administered to 12 patients with severe distress in labor. The fetal distress was documented by fetal heart rate abnormalities in association with a fetal scalp blood pH of less than 7.20. The mean fetal scalp pH was 7.17 +/- 0.17 before treatment. A 7.5- to 10-micrograms intravenous bolus of hexoprenaline was followed by an intravenous infusion titrated to inhibit uterine contractions. According to protocol, all patients delivered by cesarean section approximately 40 minutes after the bolus injection. The mean cord blood pH was 7.31 +/- 0.06. No infant had a five-minute Apgar score of less than 8, and there were no significant maternal or fetal side effects.

Quantitative analysis of amniotic fluid phospholipids in diabetic pregnant women.

Controversy exists regarding the fetal lung maturity profiles in diabetic and normal pregnancies. Diabetic and control patients at term were compared. A comprehensive lung profile was obtained using high performance liquid chromatography, lecithin:sphingomyelin ratio by conventional thin-layer chromatography, and the Lumadex foam stability index. There was no statistically significant difference in the phospholipids measured by any of the three techniques despite the fact that the control patients had a significantly higher mean gestational age at amniocentesis. As expected, the diabetic pregnancies had a significantly higher mean birth weight. There was no case of respiratory distress syndrome in either group. The present data do not allow rejection of the null hypothesis of no difference in amniotic fluid phospholipids, between diabetic and normal pregnancy, at term.

Catecholamine-mediated reduction in uteroplacental blood flow in the diet-restricted, term-pregnant rat.

To determine whether the reduction in maternal placental blood flow associated with malnutrition during pregnancy results from alpha-adrenergic vasoconstriction, we measured cardiac output, uteroplacental blood flow and uteroplacental vascular resistance in ad libitum-fed and in 50% diet-restricted term-pregnant rats, using radioactive-labeled microspheres before, and again after, alpha-adrenergic receptor blockade with phenoxybenzamine. Uteroplacental blood flow in the diet-restricted rats was 40% lower than that of the ad libitum-fed rats, before phenoxybenzamine. Phenoxybenzamine caused a 50% reduction in mean blood pressure in both the ad libitum-fed and diet-restricted rats, but did not alter cardiac output. Phenoxybenzamine decreased preplacental vascular resistance in the diet-restricted rats, resulting in no significant reduction of placental blood flow. In the ad libitum-fed rats, on the other hand, phenoxybenzamine did not alter preplacental vascular resistance, and placental blood flow decreased 45% with the fall in blood pressure. Myometrial vascular resistance was unaffected by phenoxybenzamine in either group, and myometrial blood flow decreased with the fall in blood pressure in both groups. Thus, the decreased uteroplacental blood flow associated with diet restriction is the result of increased uteroplacental alpha-adrenergic vasomotor tone.

Effect of hexoprenaline on uteroplacental blood flow in the pregnant rat.

The effect of beta-adrenergic agonists on uteroplacental blood flow is controversial. Human studies, with the use of indirect methods to assess uteroplacental blood flow, show conflicting results. Animal studies in the near-term pregnant sheep model have the disadvantages that the sheep has a syndesmochorial placenta and that the uteroplacental vessels are thought to be maximally dilated near term. The effect of hexoprenaline, a new beta 2-sympathomimetic drug, was assessed in the awake pregnant rat on day 14 of gestation by means of the radionuclide-labeled microsphere method. Hexoprenaline increased placental blood flow by 198% and distribution of cardiac output to the placentas by 229%. Renal blood flow was reduced by 24%. Saline solution administration produced no significant effects.

Effect of long-term administration of beta 2-sympathomimetic drug in the diet-restricted pregnant rat model.

To assess whether the maternal-fetal balance could be altered in favor of the fetus during malnutrition by increasing uteroplacental blood flow, 0.5 mg of hexoprenaline per day was added to the diet of one group of diet-restricted rats, while another group served as controls. The radionuclide-labeled microsphere method was used to determine blood flow to the maternal placentas and other organs. Maternal carcass weight but not fetal or placental weights were increased in the hexoprenaline-fed rats. Blood flow to the ileum, jejunum, hepatic artery, kidneys, and placentas was significantly greater in the hexoprenaline group compared with those rats fed the restricted diet alone. Although the placental blood flow was increased in the hexoprenaline-fed rats, the supply of nutrients remained restricted, and in the mother the inherent maternal-fetal balance was maintained by an increase in the blood flow to the liver and small intestine.

Use of tocolytic drugs to reverse oxytocin-induced uterine hypertonus and fetal distress.

The use of oxytocin in labor has the inherent danger of producing uterine hyperstimulation with resultant fetal distress. When produced by gradual titration of intravenous oxytocin, discontinuation of the medication is usually sufficient to reverse the process. However, the rapid administration of a large intravenous dose of oxytocin, as occurred in this patient, may result in hypertonic uterine contractions and fetal distress unresponsive to traditional measures. The rationale for using a tocolytic drug to reverse the uterine hypertonus, produce intrauterine fetal resuscitation, and prevent cesarean section is discussed in this report.

Puerperal inversion of a bicornuate, unicollis uterus. A case report.

The diagnosis and management of uterine inversion at term were complicated by an uninverted horn at the level of the contraction ring.

Maternal organ distribution of cardiac output in the diet-restricted pregnant rat.

Maternal organ distribution of cardiac output was measured with 15-micron diameter, radioactively labeled microspheres in ad libitum-fed or 50% diet-restricted, term pregnant rats, and in ad libitum-fed nonpregnant rats. The diet-restricted dams had a 33% lower total cardiac output than the ad libitum-fed dams, but it was not significantly different from that of the nonpregnant rats. Placental blood flow in the diet-restricted rats was 30% lower than that in the ad libitum-fed rats. Except for a higher blood flow to the pancreas and a lower blood flow to the uterine tissue, blood flows to the other organs of the diet-restricted dams were not significantly different from those of ad libitum-fed pregnant dams. Blood flows to the lungs, small intestine and ovaries of the diet-restricted pregnant rats were higher than those in the nonpregnant rats. Dietary restriction resulted in a decreased percentage of the cardiac output being distributed to the pregnant uterus and an increased percentage to the hepatic portal circulation, thus maintaining a liver blood flow similar to that in nonpregnant rats. Thus, maternal liver blood flow, rather than that to the placentas, is protected during malnutrition.

Uterine and cardiovascular effects of fenoterol and hexoprenaline in prostaglandin F2 alpha-induced labor in humans.

The effectiveness of the beta-sympathomimetic drugs in prostaglandin-induced labor in humans is uncertain. To assess and compare their uterine and cardiovascular effects, fenoterol (2.5 micrograms/minute) and hexoprenaline (0.38 micrograms/minute) were alternatively infused for 20 minutes in each of 12 patients having prostaglandin F2 alpha inductions of labor at term. Uterine activity was reduced to less than 29% of the pretreatment value. For similar tocolytic effects, hexoprenaline produced a significantly lesser effect on maternal heart rate than fenoterol (P = .005).

Comparison of the Lumadex-foam stability index test, lecithin: sphingomyelin ratio, and simple shake test for fetal lung maturity.

Amniotic fluid was obtained from 269 patients within 72 hours of delivery. The sensitivity, specificity, and predictive value of the Lumadex-foam stability index test, lecithin: sphingomyelin (L:S) ratio, and simple shake test were assessed in the diagnosis of respiratory distress syndrome (RDS), as well as the accuracy in identification of functional lung maturity in the growth-retarded fetus. The Lumadex-foam stability index test was found to be an accurate, quantitative, simple, and rapid measure of fetal lung maturity in the normal as well as abnormal pregnancy. The L:S ratio was accurate in the normal pregnancy, but became inaccurate in the small growth-retarded fetus. The nonquantitative simple shake test was accurate when it indicated fetal lung maturity, but an immature result was meaningless because of the large false-negative rate.

Effect of dietary restriction, during the last week only or throughout gestation, on cardiac output and uteroplacental blood flow in pregnant rats.

Cardiac output and uteroplacental blood flow were measured by using 15-microns radioactive labeled microspheres in ad libitum-fed nonpregnant female rats, and in pregnant rats: 1) fed ad libitum; 2) fed a 50% restricted diet from day 14 of gestation on; and 3) fed a 50% restricted diet from day 5 of gestation on. Dietary restriction induced fetal growth retardation regardless of duration. Cardiac output in both groups of diet-restricted dams was 30% less than that of the ad libitum-fed pregnant dams, and not significantly increased above that of the nonpregnant rats. Total uterine and placental blood flows in the dams fed the restricted diet during the last week of gestation were reduced 30-35% relative to the ad libitum-fed dams due to the reduced cardiac output. In the dams fed the restricted diet from day 5, total uterine and placental blood flows were reduced 60-65% due to both the reduced cardiac output and a decreased fractional distribution of cardiac output to the uterus. Dietary treatment had no effect on blood flow to the kidneys and ovaries. The results suggest that the reduced placental blood flow associated with maternal malnutrition-induced fetal growth retardation is caused by an inadequate expansion of maternal cardiac output, and, if malnutrition is severe enough, a fractional redistribution of cardiac output away from the uterus and developing conceptus occurs.

Accelerated pulmonary maturity as measured by the Lumadex-foam stability index test.

The Lumadex-foam stability index test and lecithin:sphingomyelin (L:S) ratio were compared in the small preterm fetus. Amniotic fluid was obtained within 72 hours of birth from 70 high-risk patients whose infants were at 34 weeks' gestation or less and/or weighed less than 2000 g. Twenty-nine infants were small for gestational age. Eleven of the 41 appropriate for gestational age babies developed respiratory distress syndrome. Conclusions of the study were as follows: 1. The Lumadex-foam stability index test is an accurate, quantitative, and rapid measure of fetal lung maturity. 2. Growth retardation accelerates functional lung maturity in the preterm fetus. 3. The foam stability index value can discriminate between the small for gestational age and appropriate for gestational age fetus at 32 weeks' gestation or less and/or less than 1500 g birth weight. 4. The L:S ratio cannot discriminate between the small for gestational age and appropriate for gestational age fetus because the false-negative rate increases as fetal weight decreases.

Cardiac output and uteroplacental blood flow in diet-restricted and diet-repleted pregnant rats.

Cardiac output and uteroplacental blood flow were measured with 15 mu radioactive microspheres in anesthetized pregnant rats which were fed: (1) ad libitum throughout gestation; (2) a 50% restricted diet from day 5 of gestation; and (3) a 50% restricted diet from days 5 to 13 of gestation and ad libitum from day 14 of gestation. An additional group of nonpregnant rats fed ad libitum was also used. Dietary restriction caused a net maternal weight loss and a 20% reduction in mean fetal weight and mean placental weight by day 21 of gestation. Restricted dams fed ad libitum during the last week of gestation showed a net maternal weight gain, while mean fetal weight, but not placental weight, was near that of the ad libitum--fed controls. In the diet-restricted rats, total cardiac output was reduced 30% relative to controls by days 20 and 21 of gestation, but cardiac output per unit maternal body weight was not significantly different. Dietary restriction decreased both total uterine and placental blood flow by about 65%. Diet repletion late in gestation did not significantly increase total cardiac output or cardiac output per unit body weight. Total uterine and placental blood flows were near those of controls, primarily because of an increased fraction of cardiac output distributed to the uterus.

Phencyclidine: its transfer across the placenta as well as into breast milk.

Phencyclidine (PCP) is a dangerous and unpredictable drug which is widely abused among young people. Acute placental transfer of this drug was studied in pregnant rabbits and mice where it was shown to cross the placenta readily. Rabbit fetal levels of radioactivity reached their peak 2 hours after parenteral administration of PCP to the doe. In the mouse, where actual PCP levels were determined, there was a tenfold higher concentration of PCP in fetal tissue than in maternal blood. In lactating mice, the drug was found to cross rapidly into breast milk where it reached concentrations which were 10 times that of plasma. As PCP may be teratogenic and has been shown to be harmful to the infant during the postnatal period, those treating pregnant women should be aware to these possible routes of exposure for the developing infant and should counsel their patients accordingly.

Meperidine metabolism in the parturient.

A study of meperidine metabolism was undertaken in 21 normal parturients at term. Meperidine, 50 mg intravenously, was the sole analgesic agent used during the intrapartum period. Maternal and cord blood assessment for meperidine and normeperidine was done by gas chromatography-mass spectrophotometry. Most maternal sera showed a typical meperidine elimination curve. A secondary rise in maternal meperidine 30 to 180 minutes after injection was found in 4 patients. One patient showed a significant alteration in normeperidine appearance. These data add further validity to the hypothesis that the pregnant woman can metabolize meperidine by several pathways.