Safe and Effective Antenatal Exercise in the First Trimester
The first trimester is the time that the embryo embeds in the uterus wall; therefore, this is the time that is most crucial in relation to miscarriage. The first 12 weeks of pregnancy is the most common time for miscarriage.
Exercise Intensity in the First Trimester
During the first trimester essential development of the foetus occurs, such as limb and organ growth, as well as increases in maternal blood volume, although there is limited weight gain. As such, it is important to be aware that body temperature regulation may be more difficult, so exercise should be of moderate intensity ( a six or seven out of 10) or at a heart rate of below 75% max.
Which are the Best Exercises in the First Trimester?
There is a possible link between high impact exercise such as running and an increased risk of miscarriage during the first 18 weeks (as seen in a Danish study of 92, 000 women carried out in 2007 by Madsen et al, the Danish Dept of Child Health). There was no risk involved with low impact exercise in the first trimester and there was no link between any exercise and miscarriage after 18 weeks.
With the exception of high impact exercise, other forms of exercise are considered beneficial during the first trimester.
The list below outlines acceptable exercise:
- Walking and cycling are excellent forms of cardiovascular exercise to aid in weight control, fitness maintenance and relaxation.
- Moderate resistance training during pregnancy can help strengthen the body and enable it to cope with the increased stress placed on it by changing body shape and weight, especially in the core, back and legs.
- Swimming is a good form of cardiovascular exercise which also provides non-weight bearing resistance. This is especially useful in the third trimester.
- Pregnancy yoga is excellent for stretching and relaxation during pregnancy.
- Pregnancy Pilates is excellent for developing core strength to help cope with the physical changes of pregnancy and recovery after childbirth.
- Kegel exercises are pelvic floor strengthening exercises that will aid in core strength during and after delivery. They are subtle contractions of the pelvic floor muscles that can be carried out in almost any situation.
How Much Exercise During the First Trimester?
As it is normal during the first trimester to still be adjusting to pregnancy, it is recommended to undertake exercise at moderate intensity up to three times per week for 30 – 45 minutes, depending on prenatal fitness levels.
As it is likely that body temperature will be elevated more quickly during pregnancy it is essential to keep well hydrated during exercise.
Sources and References:
ACSM: Impact of Physical Activity during Pregnancy and Postpartum on Chronic Disease Risk
Madsen, M. Leisure time physical exercise during pregnancy and the risk of miscarriage: a study within the Danish National Birth Cohort. Department of Child Health, National Institute of Public Health, Copenhagen K, Denmark.
American Chiropractic Board of Sports Physicians. Position Statement on Exercise and Athletic Participation During Pregnancy.
Aral et al. ACSM Current comment on Exercise During Pregnancy. www.acsm.org