Regular water aerobics workouts during pregnancy make it easier for women to deliver their babies without pain relief, new research from Brazil suggests.

Less than one third of women who took part in three 50-minute aquarobics sessions every week throughout their pregnancy requested analgesia during labor, compared to nearly two thirds of women in a control group that did not exercise, Dr. Rosa I. Pereira of the University of Campinas in Sao Paolo and her colleagues found.

“The babies had adequate weight, gestational age and vitality at birth, confirming the trend that already exists in the literature that moderate, regular physical activity has no influence on prematurity or on the weight of the newborn infant,” they write.

Exercise is now generally agreed to be safe for women with uncomplicated pregnancies, Pereira and her team point out. Exercising in the water is particularly beneficial, they add, because it helps reduce the load on the body, eases swelling, and helps prevent overheating.

To investigate how water aerobics might affect pregnancy, labor and delivery, the researchers randomly assigned 34 women to a group that did the exercises and another 37 to a control group that didn’t exercise. They tested the women’s fitness at three time points during their pregnancy.

Cardiovascular capacity and fetal heart rates remained similar in both groups throughout the course of their pregnancy. There was no difference between the groups in the length of labor or likelihood of having a C-section. Birth weights, gestational age, and newborn vitality were similar for both groups.

However, 27.3 percent of the women in the aquarobics group asked for analgesia during labor, compared with 64.9 percent of those in the control group. The difference remained significant even after the researchers accounted for the number of children the women had given birth to previously and how much education they had, both of which can influence the likelihood of asking for pain relief during labor.

The women who exercised may have been better able to withstand the rigors of labor because they were in better “psycho-physical” condition, Pereira and her team suggest.

While the findings provide strong evidence that moderate exercise is safe in pregnancy, they add, the suitability of “the exercise has to be assured since the practice of physical activity that is rigorous either in its intensity, duration or frequency is associated with low neonatal birthweight.”

SOURCE: Reproductive Health, November 21, 2008.