New Test for the Biological Assay of Oxytocin

A strip of mammary gland is removed from a lactating rabbit and suspended in a bath. The contractions of the strip are recorded isometrically. The strip shows no spontaneous activity and responds with reasonable linearity and stability to oxytocin at concentrations ranging from 0.5 to 10 milliunits per milliliter.

Terbutaline (intravenous bolus) for the treatment of acute intrapartum fetal distress

beta 2-Sympathomimetics have been used in acute intrapartum fetal distress to abolish uterine contractions and thus enable the fetal metabolism to recover before delivery. Because some serious complications were reported when a terbutaline intravenous bolus (0.25 mg) was used as a tocolytic, we assessed its safety and efficacy when used in patients not affected by cardiovascular disease, tachycardia greater than 100 beats/min, thyrotoxicosis, fluid overload, corticoids, atropine, or severe abruptio placentae. No maternal or fetal complications occurred in the 36 patients studied; a well-tolerated tachycardia developed in most patients. Fetal heart rate tracings and pH improved in 32 patients. Thirty-four neonates were delivered in good clinical and metabolic condition. We conclude that terbutaline intravenous bolus 0.25 mg is a safe and efficacious procedure when the proper indications and contraindications are followed.

A clinical test for diagnosing nuchal cords

A simple, noninvasive clinical test for detecting nuchal cords late in pregnancy and during labor is based on recording the changes in the fetal heart rate produced by transabdominal manual compression of the fetal neck area. The test was applied in 88 women close to full term and to 67 women in labor. Overall, the sensitivity of the test was 82.3% and specificity, 89.1%. The results were statistically significant in both late pregnancy and labor. A positive test implies an impending risk of cord compression and is an indication for close electronic fetal monitoring, particularly during labor. Routine use of the nuchal cord test can contribute to decreasing perinatal morbidity and mortality by diminishing the impact of cord problems.

Treatment of acute intrapartum fetal distress by beta 2-sympathomimetics

Patients with a diagnosis of severe intrapartum fetal distress by fetal heart rate and capillary blood pH monitoring received beta 2-sympathomimetics to inhibit uterine contractions (tocolysis) while the obstetric team was preparing to deliver the fetus. Fetal heart rate and acidosis significantly improved after tocolysis; these fetuses were subsequently delivered in very good metabolic and clinical condition. The favorable effect of tocolysis on fetal homeostasis is attributed to the suppression of the ischemic effect of contractions on the placental circulation. The few fetuses having an extremely compromised placental function showed no improvement in heart rate or acidosis with tocolysis and were immediately delivered. Considering the mild side effects observed, the lack of maternal complications, and the remarkable perinatal outcome obtained, we recommend using tocolysis before delivering distressed fetuses.

A descriptive analysis of involuntary bearing-down efforts during the expulsive phase of labor

A series of descriptive studies was carried out to characterize maternal respiration, type of bearing-down efforts, vocalization, and behavior; describe the obstetric conditions and intrauterine pressure associated with the bearing-down reflex; and describe the duration of second stage, fetal heart rate, and neonatal outcomes when women bear down spontaneously. Thirty-one healthy nulliparous women who had received no formal childbirth education were neither directed nor instructed to bear down with contractions. The women were supported in their involuntary bearing-down efforts throughout the second stage of their labors while the above features of their labor were recorded. The findings suggest that labor progress is adequate and fetal outcome is good when the management of the expulsion phase of labor encourages maternal pushing that is complementary with the involuntary bearing-down reflex rather than sustained breath-holding. These findings support the necessity for further research regarding the bearing-down techniques used during labor.

Effects of lateral recumbency and sitting on the first stage of labor

We compared uterine activity in lateral recumbency and the sitting position during the first stage of labor in a group of nulliparas. Lateral recumbency was accompanied by more intense, less frequent and more efficient uterine contractions than sitting. Patients preferred sitting for the first half of labor and lateral recumbency for the second. No adverse fetal reaction was noticed in either position, judging from the fetal heart rate. An increase in maternal pulse rate during sitting could have indirectly indicated some compression of the prevertebral vessels. Maternal position clearly affects several parameters of labor, and its selection should be based upon maternal comfort, uterine contractility and efficiency, and hemodynamic repercussions.