1152 Letters
April 1991 Am J Obstet Gynecol
nervous system damage because of intrapartum asphyxia needs to be evaluated in prospective clinical studies. Ramiah Ramasubramanian, MB, BS, Michele Mohajer, MB, BS, Edwin M. Symonds, MD, Mark C. Luxton, MB, ChB, and Alan R. Aitkenhead, MD
"Does occupational vibration affect the course and outcome of pregnancy?" it is important to lobby for increased worker protection, worker education, and applied research in this emerging and growing area of concern for working pregnant women. Robert M. Abrams, PhD
Departments of Anesthesia and Obstetrics/Gynecology, University Hospital, Queen's Medical Center, Nottingham NG7 2UH, United Kingdom
University of Florida, Department of Obstetrics and Gynecology, Box J-294 JHMHC, Gainesville, FL 32610-0294
REFERENCES 1. Whittle MJ. An overview of fetal monitoring. Clin Obstet GynaecoI1987;1:203-18. 2. Kirk DL, Smith PRo Techniques for the routine on-line processing of the fetal electrocardiogram. j Perinat Med 1986;14:391-7. 3. Murray HG. The fetal electrocardiogram: current clinical developments in Nottingham. j Perinat Med 1986; 14:399404. 4. jongsma HW, van Oosterom A, Murray HG, van Geijn HP. Introduction to fetal electrocardiography.] Perinat Med 1986;14:347.
Occupational vibration during pregnancy To the Editors: Women are entering the workplace in increasing numbers' and are diversifying their choice of employment to include jobs in agriculture, construction, forestry, mining, transportation, and heavy industries in which vibration of all or parts of their bodies is significant. As a potential environmental hazard for a subset of working women who are pregnant, occupational vibration has received very little attention. Although it is to be expected that prolonged exposure to vibration could result in increased fatigue and diminished performance;- 3 certain conditions already present in pregnancy, such as abdominal and lower back pain, could be aggravated" Low-frequency vibrations easily pass through the abdominal wall, uterine tissues, and fetal fluids 5 and could also have some adverse effects on the developing embryo or fetus. Jobs in which the whole body is exposed to vibrations of 4 to 8 Hz are most risky, for it is in this range that the abdominal segment "resonates"3 and is least likely to resist the oscillation forces that are imparted by machines on which women stand and sit or against which they lean. As a group, obstetricians have done the most to publicize the fact that vibratory mechanical forces that are applied to the abdominal skin of pregnant women are easily transmitted to the fetus; in most cases, this results in fetal movements and cardioacceleration. 6 . 7 The fetal vibroacoustic stimulation test appears to be useful in confirming the presence of a healthy fetus that is destined for a healthy birth.8 It is now time to broaden this clinical interest to include the effects of occupational vibration on pregnancy outcome. Unfortunately, the usual indices of outcome-premature birth, birth defects, Apgar and other neonatal scores-may not be sensitive enough to assess this type of exposure accurately. Until a definite answer can be given to the question,
Donald E. Wasserman, MSEE Wasserman and Associates, Cincinnati, OH 45242
REFERENCES 1. Pelmear PL. Low frequency noise and vibration: role of government in occupational disease. Semin Perinatol 1990; 14:322-8. 2. Dupuis H, Zerlette G. The effects of wholebody vibration. New York: Springer-Verlag, 1986. 3. Wasserman DE. Human aspects of occupational vibration. In: Salvendy G, ed. Advances in human factors/ergonomics. New York: Elsevier, 1987:3. 4. Lidstrom 1M. Pregnant women in the workplace. Semin Perinatol 1990; 14:329-33. 5. Gerhardt Kj, Abrams RM, Oliver CC. Sound environment of the fetal sheep. AM j OBSTET GYNECOL 1990;162: 282-7. 6. Read ]A, Miller FC. Fetal heart rate acceleration in response to acoustic stimulation as a measure of fetal wellbeing. AM] OBSTET GYNECOL 1977;129:512. 7. Gagnon R. Stimulation of human fetuses with sound and vibration. Semin Perinatol 1989; 13:353-433. 8. Richards DS. Fetal vibroacoustic stimulation test. Semin Perinatol 1990; 14:305-10.
Group B streptococcal disease To the Editors: We read the interesting article by Silver et al. (Silver HM, Gibbs RS, Gray BM, Dillon He. Risk factors for perinatal group B streptococcal disease after amniotic fluid colonization. AM J OBSTET GYNECOL 1990;163:19-25) and we would like to add some data from our experience,' which could clear up some points. In the first place, while studying at-risk patients (intraamniotic infection or rupture membranes> 10 hours), the authors found that 81 % of group B streptococcal vaginal carriers had group B streptococci in amniotic fluid during labor. They stated, "It is not possible to determine whether this is a usual occurrence or simply related to the method of patient selection." Because the reported value is similar to the 86% we found in our study of amniotic fluids 2 hours after rupture of the membranes in unselected intrapartum group B streptococcal carriers,' the majority of whom show no signs of intraamniotic infection, we think we may conclude that it is really a usual occurrence, even in patients without evidence of intraamniotic infection. Similarly, the neonatal colonization rate reported when group B streptococci were cultured in amniotic fluid was 76%, compared with 69% in our work when they were cultured in amniotic fluid and/ or in the vagina during delivery. Finally, we would like to point out an interesting finding of the authors not mentioned in the discussion: 12% of patients had group B streptococci in amniotic fluid
April 1991 Am J Obstet Gynecol
nervous system damage because of intrapartum asphyxia needs to be evaluated in prospective clinical studies. Ramiah Ramasubramanian, MB, BS, Michele Mohajer, MB, BS, Edwin M. Symonds, MD, Mark C. Luxton, MB, ChB, and Alan R. Aitkenhead, MD
"Does occupational vibration affect the course and outcome of pregnancy?" it is important to lobby for increased worker protection, worker education, and applied research in this emerging and growing area of concern for working pregnant women. Robert M. Abrams, PhD
Departments of Anesthesia and Obstetrics/Gynecology, University Hospital, Queen's Medical Center, Nottingham NG7 2UH, United Kingdom
University of Florida, Department of Obstetrics and Gynecology, Box J-294 JHMHC, Gainesville, FL 32610-0294
REFERENCES 1. Whittle MJ. An overview of fetal monitoring. Clin Obstet GynaecoI1987;1:203-18. 2. Kirk DL, Smith PRo Techniques for the routine on-line processing of the fetal electrocardiogram. j Perinat Med 1986;14:391-7. 3. Murray HG. The fetal electrocardiogram: current clinical developments in Nottingham. j Perinat Med 1986; 14:399404. 4. jongsma HW, van Oosterom A, Murray HG, van Geijn HP. Introduction to fetal electrocardiography.] Perinat Med 1986;14:347.
Occupational vibration during pregnancy To the Editors: Women are entering the workplace in increasing numbers' and are diversifying their choice of employment to include jobs in agriculture, construction, forestry, mining, transportation, and heavy industries in which vibration of all or parts of their bodies is significant. As a potential environmental hazard for a subset of working women who are pregnant, occupational vibration has received very little attention. Although it is to be expected that prolonged exposure to vibration could result in increased fatigue and diminished performance;- 3 certain conditions already present in pregnancy, such as abdominal and lower back pain, could be aggravated" Low-frequency vibrations easily pass through the abdominal wall, uterine tissues, and fetal fluids 5 and could also have some adverse effects on the developing embryo or fetus. Jobs in which the whole body is exposed to vibrations of 4 to 8 Hz are most risky, for it is in this range that the abdominal segment "resonates"3 and is least likely to resist the oscillation forces that are imparted by machines on which women stand and sit or against which they lean. As a group, obstetricians have done the most to publicize the fact that vibratory mechanical forces that are applied to the abdominal skin of pregnant women are easily transmitted to the fetus; in most cases, this results in fetal movements and cardioacceleration. 6 . 7 The fetal vibroacoustic stimulation test appears to be useful in confirming the presence of a healthy fetus that is destined for a healthy birth.8 It is now time to broaden this clinical interest to include the effects of occupational vibration on pregnancy outcome. Unfortunately, the usual indices of outcome-premature birth, birth defects, Apgar and other neonatal scores-may not be sensitive enough to assess this type of exposure accurately. Until a definite answer can be given to the question,
Donald E. Wasserman, MSEE Wasserman and Associates, Cincinnati, OH 45242
REFERENCES 1. Pelmear PL. Low frequency noise and vibration: role of government in occupational disease. Semin Perinatol 1990; 14:322-8. 2. Dupuis H, Zerlette G. The effects of wholebody vibration. New York: Springer-Verlag, 1986. 3. Wasserman DE. Human aspects of occupational vibration. In: Salvendy G, ed. Advances in human factors/ergonomics. New York: Elsevier, 1987:3. 4. Lidstrom 1M. Pregnant women in the workplace. Semin Perinatol 1990; 14:329-33. 5. Gerhardt Kj, Abrams RM, Oliver CC. Sound environment of the fetal sheep. AM j OBSTET GYNECOL 1990;162: 282-7. 6. Read ]A, Miller FC. Fetal heart rate acceleration in response to acoustic stimulation as a measure of fetal wellbeing. AM] OBSTET GYNECOL 1977;129:512. 7. Gagnon R. Stimulation of human fetuses with sound and vibration. Semin Perinatol 1989; 13:353-433. 8. Richards DS. Fetal vibroacoustic stimulation test. Semin Perinatol 1990; 14:305-10.
Group B streptococcal disease To the Editors: We read the interesting article by Silver et al. (Silver HM, Gibbs RS, Gray BM, Dillon He. Risk factors for perinatal group B streptococcal disease after amniotic fluid colonization. AM J OBSTET GYNECOL 1990;163:19-25) and we would like to add some data from our experience,' which could clear up some points. In the first place, while studying at-risk patients (intraamniotic infection or rupture membranes> 10 hours), the authors found that 81 % of group B streptococcal vaginal carriers had group B streptococci in amniotic fluid during labor. They stated, "It is not possible to determine whether this is a usual occurrence or simply related to the method of patient selection." Because the reported value is similar to the 86% we found in our study of amniotic fluids 2 hours after rupture of the membranes in unselected intrapartum group B streptococcal carriers,' the majority of whom show no signs of intraamniotic infection, we think we may conclude that it is really a usual occurrence, even in patients without evidence of intraamniotic infection. Similarly, the neonatal colonization rate reported when group B streptococci were cultured in amniotic fluid was 76%, compared with 69% in our work when they were cultured in amniotic fluid and/ or in the vagina during delivery. Finally, we would like to point out an interesting finding of the authors not mentioned in the discussion: 12% of patients had group B streptococci in amniotic fluid
