When a pregnant woman experiences bradycardia, or slow heart rate, it can have negative consequences for her health and that of her unborn child. Fortunately, access to pregnancy health care can often prevent and even resolve any medical issues related to slow maternal heart rate. Always bring any questions you have about your own and your baby's health to your doctor.
The fetal heart and circulatory system develop at an astonishing rate, starting within the first week after conception. The baby's heart beats by four weeks. The mother's cardiovascular system changes as well, beginning at about five weeks post-conception. Her total blood volume normally increases by 40 to 50 percent so that she can properly nourish both her own tissues and those of her rapidly growing fetus.
Maternal Heart Rate
The normal heart rate for a nonpregnant woman is around 70 to 85 beats per minute. To support the expansion of her blood volume that occurs with pregnancy, the mother's heart rate must rise to an additional 10 to 15 beats per minute. Generally, if you are pregnant and your heart rate is less than 60 beats per minute, your doctor should evaluate you thoroughly for any underlying cardiovascular or other medical issues.
Causes and Effects of Maternal Bradycardia
MayoClinic.com identifies many possible causes for slow heart rate, including some medications; a congenital heart impairment; hypertension or high blood pressure; a heart infection; scarring from heart surgery; a disorder that causes excessive iron in the body; hypothyroidism, or low thyroid; sleep apnea, a breathing disorder; and a blood imbalance of certain chemicals called electrolytes.
Maternal bradycardia deprives both mother and fetus of oxygen. The mother can have such symptoms as fainting, chest pains, weakness, fatigue and shortness of breath. If you are having any such symptoms, please seek proper, prompt medical diagnosis for your own and your baby's sake. Especially if untreated, maternal bradycardia can lead to fetal bradycardia, complications of labor and delivery, prematurity and fetal death.
As the Merck Manual notes, most women "who have heart disorders...can safely give birth to healthy children, without any permanent ill effects on heart function or life span." Maternal bradycardia can often be alleviated through treatment of any underlying diseases, by changes in prescription medications or with a pacemaker. Talk with your doctor about all treatment and learn which option or combination of options might provide the most benefits and pose the fewest risks to you and your baby.
Maternal heart disorders affect the care of about 1 percent of pregnancies. If you are pregnant and worried or certain that you have bradycardia or any other heart problems, hopefully you and your baby already have access to health care. If you do not already know where to go for pregnancy health care, contact your local health department. There are also many local, state and federal government websites that can provide information about free and low-cost health care and resources. One such site is the Health Resources and Services Administration's Find a Health Center page.