The Effects on Baby
In the past, one of the main concerns about exercise during pregnancy was that it would have a negative effect on your baby. Some researchers predicted growth restriction, oxygen reduction, and other scary outcomes for babies born to moms who exercised. To the contrary, researchers have now found that there are many physical and psychological benefits for a baby when Mom exercises during pregnancy.
As you become more aware of your pregnant body and your baby, you focus on taking proper care of that body and baby. By watching how and what you eat, you decrease the risks of preterm labor. The decrease in preterm birth rates alone prevents many neonatal deaths, as preterm birth is one of the leading causes of death in newborns.
How can I monitor my baby's well-being?
Your practitioner will monitor your baby in a couple of ways during your pregnancy. One way will be by measuring the heart rate; another is the growth rate as judged by the growth of your uterus. Your baby's normal heart rate will probably be between 120 and 160 beats per minute (bpm). After 20 weeks, your uterus will generally measure within one to two weeks of the number of weeks you are pregnant. The measurements are in centimeters, from the public bone to the top of the fundus.
The improved blood circulation of the mother through exercise can help grow a healthier placenta, which is the baby's lifeline during pregnancy, as it uses the placenta to get nutrients and oxygen and to expel waste products. The heartier the placenta, the healthier the baby will be.
Improved Labor Tolerance
Babies of mothers who exercise also seem to tolerate labor better. These babies are used to having Mom work hard while exercising, so that when it is time for Mom to have contractions — it is just another workout for them. This tolerance level has also shown to decrease the incidence of meconium (baby's first stool) in the amniotic fluid at birth. Having too much meconium in the amniotic fluid is potentially life-threatening and something you would prefer to avoid.
You can also monitor your baby between prenatal visits using fetal kick counts. At the same time every day, relax for 30 minutes and notice how long it takes Baby to reach 10 movements. It should take about the same amount of time each day, usually less than an hour. If an hour is up and you need more movements, eat something and try again. If there is still a decrease or change in the number of movements, report it immediately to your doctor or midwife.
Leaner, Healthier Babies
If you exercise during pregnancy, your baby will tend to be of a lower birth weight. While this might seem like a negative outcome, the lower weight is not from fetal growth restriction, but rather the reduction in deposits of unnecessary fat for the baby. These leaner babies at birth are also healthier and leaner later in life. Some studies even report that babies born to mothers who exercised during pregnancy were easier to care for after birth and seemed to adjust to their environments more readily.
Perhaps these babies are reported to be easier because the rocking motions associated with maternal exercise during pregnancy offered stimulation to enhance baby's brain development. One study, “Morphometric and neurodevelopmental outcome at age five years of the offspring of women who continued to exercise regularly throughout pregnancy” (J. Pediatr. 1996 Dec; 129:856-63), shows that these babies actually had better language and intelligence scores at five years of life.
It is clear, then, that babies enjoy many benefits from having a healthy mother and a healthy pregnancy. They are heartier and healthier. They also seem to do better than other babies in a similar situation.
Recent studies have shown that exercise in pregnancy is a safe and effective way to maintain a healthy pregnancy. While this has not always been the thinking, we now see the benefits to maintaining the strength and flexibility of the pregnant body. You and your baby have many benefits to gain.