Fetal movement during labor

Expulsion of liquid from the fetal lung during labour in sheep

Effective gas exchange after birth requires clearance of most of the liquid filling the lung during gestation. To date the focus has been on active Na(+) transport from lung lumen to interstitium, but Na(+) transport begins only close to delivery, making it an unlikely mechanism for clearing the bulk of fetal lung liquid. We hypothesised that fetal trunk muscle contractions, known to occur in labour, are involved in lung liquid clearance. We measured maternal uterine contractions, fetal tracheal flow directly and fetal electromyograms in thoracic and abdominal muscles. During labour in five fetal sheep, brief flow pulses were observed in the trachea, most of which expelled a small volume of lung liquid. Tracheal flow pulses were associated with fetal muscle contractions 89% of the time, which were associated on 91% of occasions with uterine contractions. Our results suggest that liquid contained in the fetal lung is cleared before and during labour as a result of fetal muscular effort, perhaps stimulated by uterine contractions.

Intra- and early postpartum ultrasonography: a review. Part II

Part II is a continuation of the preceding segment, which appeared in the previous issue (Survey 1998;53:000-000). This part presents data pertaining to ultrasound-guided procedures (invasive and noninvasive), physiology (fetal behavior), intrapartum hemorrhage, the third stage of labor, post-partum hemorrhage, and postcaesarean ultrasonography. In addition, this article includes data regarding nonobstetric ultrasound including anesthesiology, catheter placement, venous air embolism, effect of epidural anesthesia on uterine blood flow, and urinary retention. Finally, this part presents ultrasonographic data of the maternal cerebral circulation in preeclampsia/eclampsia and of the maternal deep venous system.

Fetal heart rate accelerations, fetal movement, and fetal behavior patterns in twin gestations

OBJECTIVE

Previous studies have shown that twins, when monitored simultaneously, show a remarkably high incidence of coincident fetal heart rate accelerations (about 58%). The current study examines synchrony of behavior patterns in twins.

STUDY DESIGN

We examined 37 fetal monitor strips from 15 sets of twins with simultaneous fetal heart rate and fetal movement recorded by means of Doppler techniques (Toitu MT-430 fetal actocardiograph). The strips were analyzed for coincidence of fetal heart rate accelerations and fetal movement episodes and then conceptually for synchrony of fetal behavior patterns on the basis of descriptions of behavioral states by Prechtl.

RESULTS

Thirty-six percent of fetal heart rate accelerations were found to be simultaneous. Forty-three percent of movement epochs were considered simultaneous. We found that twins exhibited synchronous behavior patterns (basically sleep or awake state) 94.7% of the time.

CONCLUSION

Twin-twin interactions are more consistently related than suspected when observation is limited to heart rate alone, and the synchrony and role of fetal behavior states must be considered when twin interactions and behavior are studied.

The effect of maternal intravenous glucose administration on fetal activity

OBJECTIVE

The study was designed to objectively evaluate the effect of maternal intravenous glucose infusion on fetal activity.

STUDY DESIGN

Twenty-one volunteers at 30.7 +/- 3.0 weeks' gestation were objectively evaluated for fetal activity with a Doppler monitor before and during an intravenous glucose test. Baseline fetal activity monitoring began 10 minutes before a fasting blood glucose level was obtained. A standard 1-hour intravenous glucose tolerance test was then performed, and fetal activity monitoring was continued for the duration of the test. Twenty-one women at 29.8 +/- 3.0 weeks' gestation volunteered to serve as controls and were continuously monitored for fetal activity. The control patients did not receive intravenous glucose.

RESULTS

Linear regression analysis revealed an increase in fetal activity in both groups; however, the increase in the glucose infusion group was significantly greater than in the control group.

CONCLUSIONS

Maternal glucose infusion causes short-term stimulation of fetal activity; however, some other factor in the monitoring process also stimulates fetal activity.

Position of the vibroacoustic stimulator does not affect fetal response

OBJECTIVE

This study was designed to compare the fetal response to the vibroacoustic stimulation test when applied alternately over the fetal vertex or breech.

STUDY DESIGN

Two hundred five patients with a nonreactive nonstress test after 10 minutes were prospectively randomized to receive the vibroacoustic stimulation test over the fetal vertex (n = 115) or the fetal breech (n = 90). Fetal heart rate reactivity was evaluated. Two patient subsets were evaluated for fetal movement (n = 37) and the fetal startle response (n = 20) after the vibroacoustic stimulation test.

RESULTS

Virtually identical fetal heart rate responses and increases in fetal movement were observed after vibroacoustic stimulation over the fetal vertex or breech. The fetal startle response was uniformly observed in both groups.

CONCLUSION

Vibroacoustic stimulation over the fetal breech elicits an identical short-term fetal response compared with stimulation over the fetal vertex, potentially reducing the intensity of sound exposure at the fetal ear.