The development of fetal heart rate patterns during normal pregnancy

Article Abstract:

Because the relevance of fetal heart rate (FHR) recordings for monitoring fetal health remains a subject of debate, a study of normal FHR patterns during fetal activity and behavioral states was carried out. Forty-three women at low risk for complications were monitored every four weeks during the second and third trimesters of their pregnancies. FHR was recorded for intervals of 90 to 100 minutes; this information was correlated with fetal eye, body, limb, diaphragmatic, and mouth movements, as imaged with ultrasound. Most fetuses showed FHR acceleration during movement only after 24 weeks' gestation; in fetuses younger than 22 weeks, these accelerations lasted as long as 10 seconds. The decelerations increased in number during the second trimester, but their occurrence was not related to acceleration. In later pregnancy, deceleration, when present, followed acceleration, with a quick return to normal FHR. Well-defined fetal behavioral states, with consistent patterns of body and eye movements and FHR changes, appeared in most fetuses after 35 weeks. Older fetuses had slower FHRs; after 16 weeks' gestational age, the rate fell 1 beat per minute per week until delivery. Variability in baseline FHR levels increased with advancing age, but became more consistent during quiet periods after 30 weeks. The FHR became a good indicator of fetal behavioral states from this point on. Based on the results, in fetuses younger than 30 gestational weeks, a FHR of 10 beats per minute for 10 seconds is a better criterion for a normal nonstress test than the currently used 15 beats per minute for 15 seconds. Almost all fetuses had episodes of rhythmical mouthing movements during quiet periods. During these periods, FHR oscillations were common, and such patterns should not be considered abnormal. True fetal sucking rarely occurs. Accurate interpretation of FHR patterns requires an understanding of normal behavioral and cyclical variability, as detailed in these studies. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Fetal heart rate

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Hiccups and breathing in human fetuses

Article Abstract:

Little is known regarding breathing and hiccups in fetuses, two of the movements performed by the fetal diaphragm. Suppression of breathing may indicate early fetal infection after the maternal membranes surrounding the fetus have ruptured prematurely, but patterns of normal breathing for low-risk fetuses have not been examined. To address this issue, 45 fetuses were monitored using ultrasound techniques that measured their diaphragmatic movements and heart rates, as well as eye, body, and mouth movements. The recording periods lasted 90 to 100 minutes, and test sessions began between 14 and 18 weeks' gestation, continuing monthly until delivery. Results from 268 recordings showed an increase in the proportion of time devoted to breathing after the age of 26 weeks' gestation, whereas hiccups were more common prior to 24 weeks' gestation. Some fetuses at all gestational ages except 32 to 36 weeks demonstrated no breathing at all. With development, the fetuses showed clearer cycles of rest and activity, with longer intervals of complete cessation of activity. Breathing movements were always more frequent during activity cycles, and hiccups only occurred in active cycles. All infants were born between 37 and 42 weeks' gestation; all but two developed normally. Of the two, one developed a fever, which resolved; the other died of unknown causes at the age of eight weeks. The results suggest that control of the diaphragmatic movements that result in fetal breathing is different from control of the movements that result in hiccups, and that hiccups, being earlier, is the simpler movement. A discussion is provided of the relationship between breathing movements and the development of the fetal lung. When breathing studies of fetuses are undertaken for clinical purposes, prolonged recordings should be made with awareness of the state-dependence (active versus resting) of breathing and hiccups. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Respiration, Diaphragm, Diaphragm (Anatomy), Hiccups

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Preterm prelabour rupture of membranes

Article Abstract:

Preterm prelabor rupture of membranes (PPROM) refers to rupture of the amniotic sac (or bag of waters) before the onset of labor and before the 37th week of pregnancy. Depending on the population studied, the incidence (number of new cases) of PPROM has been reported to be between 1 and 10 percent of pregnancies. When elective preterm delivery and fetal death before labor are excluded, PPROM is estimated to affect 40 to 60 percent of women who deliver prematurely. The main risk factors associated with PPROM are smoking and vaginal bleeding. The exact cause of PPROM is unknown, but suggested causes include infection, membrane abnormalities, increased pressure within the uterus, and cervical incompetence. The most serious complications of PPROM are preterm labor, preterm delivery (which is associated with low birth weight), uterine infection, and lung disease in the newborn. Other possible complications associated with PPROM include deformities caused by a lack of amniotic fluid, premature detachment of the placenta, and difficult delivery. Approximately 60 percent of the women who experience PPROM prior to the 24th week of pregnancy and 80 percent of those with PPROM after the 34th week go into labor within 1 week. When PPROM occurs, attempts should be made to prolong the pregnancy to 32 to 34 weeks. Corticosteroid treatment for pregnant woman with PPROM has been shown to reduce the risk of lung problems in the newborn. Women with PPROM should be examined for signs of infection in the uterus and, if infection occurs, antibiotic treatment should be started. Additional factors that may increase infant survival are: determination of the accurate length of the pregnancy (or gestational age of the fetus), early diagnosis of PPROM, and transfer of the premature, sick infant to an appropriate neonatal intensive care unit, if necessary. (Consumer Summary produced by Reliance Medical Information, Inc.)

Care and treatment, Complications and side effects, Premature rupture of membranes, Premature rupture of the membrane, Premature labor, Pregnancy, Complications of, Pregnancy complications

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