Changes in 24-hour heart rate variability during normal pregnancy.

OBJECTIVE We studied the effects of normal pregnancy on heart rate variability as a noninvasive index of maternal cardiovascular autonomic modulation. STUDY DESIGN Twenty-four-hour Holter recordings were obtained for 8 healthy pregnant volunteers during early pregnancy (</=6 weeks after conception); at 10, 18, and 34 weeks after conception; and while the subjects were not pregnant. Another 12 subjects underwent 2 to 4 recordings in the sequence. Heart rate variability and nighttime respiratory rates were determined. RESULTS Maternal heart rate variability declined during pregnancy. Virtually all indexes were significantly decreased with respect to the nonpregnant state in early pregnancy, and respiratory rate was increased. Changes in heart rate, heart rate variability, and respiratory rates between subsequent stages were modest. Individual changes in heart rate, heart rate variability, and respiration during pregnancy varied in both magnitude and direction. CONCLUSION Most of the change in cardiac autonomic modulation and respiration during pregnancy occurs within the first 6 weeks after conception. There is considerable variability in individual heart rate and heart rate variability changes during a normal pregnancy.

[1]  Circadian rhythm of frequency‐domain measures of heart rate variability in pregnancy , 1997, British journal of obstetrics and gynaecology.

[2]  J. Pritchard,et al.  BLOOD VOLUME CHANGES IN PREGNANCY AND THE PUERPERIUM. III. WHOLE BODY AND LARGE VESSEL HEMATOCRITS IN PREGNANT AND NONPREGNANT WOMEN. , 1962, American journal of obstetrics and gynecology.

[3]  J. C. Donovan,et al.  Blood volume during pregnancy. Significance of plasma and red cell volumes. , 1967, American journal of obstetrics and gynecology.

[4]  R. Erkkola,et al.  Cardiovascular autonomic reflexes in mid‐pregnancy , 1993, British journal of obstetrics and gynaecology.

[5]  P. Stein,et al.  Heart Rate Variability Reflects Severity of COPD in PiZ α1-Antitrypsin Deficiency , 1998 .

[6]  B. Seaward,et al.  Maternal physiologic adaptations to early human pregnancy , 1988 .

[7]  J. Fleiss,et al.  Efficient estimation of the heart period power spectrum suitable for physiologic or pharmacologic studies. , 1990, The American journal of cardiology.

[8]  P. Stein,et al.  Insights from the study of heart rate variability. , 1999, Annual review of medicine.

[9]  P. Salmela,et al.  Autonomic Influence on Pregnancy Outcome in IDDM , 1990, Diabetes Care.

[10]  P. Hjemdahl,et al.  Cardiovascular responses to circulating catecholamines in normal pregnancy and in pregnancy-induced hypertension. , 1985, Clinical physiology.

[11]  S.M. Kay,et al.  Spectrum analysis—A modern perspective , 1981, Proceedings of the IEEE.

[12]  A. Nataraj,et al.  The Valsalva maneuver: a test of autonomic nervous system function in pregnancy. , 1983, American journal of obstetrics and gynecology.

[13]  J. Patrick,et al.  A longitudinal study of respiratory changes in normal human pregnancy with cross-sectional data on subjects with pregnancy-induced hypertension. , 1990, American journal of obstetrics and gynecology.

[14]  S. Malpas,et al.  Heart-Rate Variability and Cardiac Autonomic Function in Diabetes , 1990, Diabetes.

[15]  L. Peeters,et al.  Severely impaired fetal growth is preceded by maternal hemodynamic maladaptation in very early pregnancy , 1995, Acta obstetricia et gynecologica Scandinavica.

[16]  P. Stein,et al.  Heart rate variability: a measure of cardiac autonomic tone. , 1994, American heart journal.

[17]  E. Ekholm,et al.  Autonomic cardiovascular control in pregnancy. , 1996, European journal of obstetrics, gynecology, and reproductive biology.

[18]  J. Pritchard,et al.  BLOOD VOLUME CHANGES IN PREGNANCY AND THE PUERPERIUM. III. WHOLE BODY AND LARGE VESSEL HEMATOCRITS IN PREGNANT AND NONPREGNANT WOMEN. , 1962, American journal of obstetrics and gynecology.

[19]  J. Clapp,et al.  Maternal heart rate in pregnancy. , 1985, American journal of obstetrics and gynecology.

[20]  J M Neilson,et al.  Twenty four hour heart rate variability: effects of posture, sleep, and time of day in healthy controls and comparison with bedside tests of autonomic function in diabetic patients. , 1991, British heart journal.

[21]  J. Clapp,et al.  Cardiovascular function before, during, and after the first and subsequent pregnancies. , 1997, The American journal of cardiology.

[22]  E. Braunwald,et al.  Control of Heart Rate by the Autonomic Nervous System: Studies in Man on the Interrelation Between Baroreceptor Mechanisms and Exercise , 1966, Circulation research.

[23]  E. Capeless,et al.  Cardiovascular changes in early phase of pregnancy , 1989, American journal of obstetrics and gynecology.