PM&R News   •   January 2018

One of physiatrist’s main goals is to counsel patients about exercise and to modify exercise based on certain circumstances. Pregnancy is one of those circumstances that many physiatrists have a difficult time counseling on. What is the appropriate amount of exercise to not only do no harm to the developing baby, but to also help the mother and baby be as healthy as possible. Past studies have shown that moderate exercise can improve placental function in pregnancies that are low risk, but little is known about effects on birth weight.

A recent study evaluated effect on infant’s birth weight due to physical activity during pregnancy. The study found that as pregnancy progressed, mothers decreased their energy expenditure from 35.5% during the first trimester to 18.6% in the third trimester. Women doing at least 3 hours/week of brisk walking had infants with a 29.72 gram decrease weight compared to those who performed 0 hours/week in the first trimester, with no association of decrease weight with exercise in the 2^nd or third trimester. There was no association of small for gestational age with increasing activity, but there was a decrease in large for gestational age associated with increase in vigorous activity. If women developed pre-eclampsia, their infant experienced a 20g decrease in birth weight for each 1 MET/hour/week increase in vigorous activity. Finally, exercise in pregnancy has been shown to decrease the amount of adiposity in the infant’s body weight decreasing childhood obesity risk.

So what does this mean for your patients? One can counsel their patients that exercise is safe in pregnancy and can actually have some health benefits to their infant. However, if a patient develops pre-eclampsia, the physiatrist should caution the patient about the potential for inappropriate low birth weight. This is theorized to be due from inability of the placental to adapt to these high blood flow states. New year’s is a popular time for conception and we hope you are prepared for pregnancy associated exercise in the new year.