The safety of structured resistance and cardiovascular training for the expecting mother has been widely investigated during the previous three decades. The majority of the literature demonstrates that moderate intensity training using appropriate exercise protocol can provide numerous benefits for the health of the mother and unborn child alike. Just a few of these benefits include: improvements in cardiorespiratory fitness, improved psychological well-being, reduced maternal weight gain, reduced musculoskeletal discomfort, reduced incidence of lower back pain, reduced postural compromise, decreased incidence of vascular incompetence, and fewer complications during delivery. There are precautions that must be taken however to ensure safety of the pregnant individual, and a physician’s approval should always be obtained.

Some major contraindications to exercise for the expectant mother include: pregnancy-induced hypertension, an incompetent cervix, premature placental rupture, persistent bleeding, or any pre-existing cardiopulmonary diseases. There are also some general considerations that must be applied to any exercise protocol for the pregnant female. The following list outlines general recommendations for training during pregnancy.

Fundamental Pregnancy Training Recommendations

1. Contact the primary health care provider prior to participating in exercise.
2. Avoid exercise in the supine or prone positions following the 1st trimester.
3. Avoid jumping or explosive activities.
4. Avoid training in the heat and maintain adequate hydration at all times.
5. Ensure adequate caloric intake.
6. Discontinue exercise upon fatigue.
7. Keep resistance training loads within the moderate range.
8. Beware of joint laxity during all activities.

In a recent study published in the International Journal of Obesity, researchers investigated the effects of resistance training during pregnancy on the newborn’s birth size. The participants included 160 sedentary pregnant individuals who were randomly assigned into a training group or control group. Light-intensity resistance training was performed three times per week (35-40 minutes per session) during the second and third trimester by the 80 participants in the training group. Birth weight and length, head circumference of the newborn, gestational age at time of delivery, maternal weight and height before parity, and gestational weight gain were recorded. The results exposed the correlation of greater maternal body weight prior to pregnancy and a greater newborn birth size. Furthermore, the training group protocol saw no negative impact on the newborn’s body size or overall health. This potentially offers the conclusion that exercise interventions may assuage the unfavorable consequences of increased pre-pregnancy maternal bodyweight on the newborn’s birth size.

In a similar study presented in the journal Obstetrics and Gynecology, researchers attempted to show an association between regular exercise before and during pregnancy and excessive newborn birth weight. Statistics from the Norwegian Mother and Child Cohort Study were utilized in the study; particularly questionnaire data derived from 36,869 pregnancies that lasted at least 37 weeks. The questionnaire data used pertained to exercise levels during pregnancy and newborn birth weight. The main outcome measure was excessive birth weight; expressed as weight at or above the 90th percentile. Logistic regression analyses were used to estimate the association between exercise and newborn weight for nulliparous (mothers who are having their first child) and multiparous (mothers who have delivered a child previously) individuals separately. The results demonstrated that there was minimal effect of regular exercise before pregnancy on the probability of delivering a newborn of excessive weight, but regular exercise during pregnancy appeared to reduce the odds of delivering an overweight newborn by 23-28%.

As research pointedly shows that physical activity during pregnancy can positively affect the mother and child, the health and fitness professional should be able to confidently implement training programs within defined exercise recommendations. However, the fitness professional who plans to provide exercise prescription for a pregnant individual must be sure to be educated in terms of appropriate intensity, exercise selection, and other applicable training parameters. As with all special populations explicit safety measures must be maintained and particular considerations observed; but it appears clear that the risk to benefit ratio for training before or during pregnancy should encourage prudent structured exercise for the expecting mother.