Hi Steph,
We have a large and busy preconceptual counseling program down here at the University of North Carolina. Preconceptual counseling serves a variety of purposes. The most important goal is to provide the patient, and her partner if desired, information with which they can use to make informed decisions about their future reproduction. Information regarding exercise would be a prime concern for you and your husband right now. In today's society many women like you are engaged in strenuous physical activity. Preconceptual counseling regarding exercise takes into account the type and extent of exercise that the patient undertakes, the physiologic effects of exercise on her and the psychological gains that she gets from exercise. Counseling also takes into account baseline information regarding the patient's menstrual history, reproductive history and her perception of the effect of pregnancy on her current exercise program.
Hyperthermia (increased core temperature) may be the most serious risk of strenuous exercise during the periconceptual period. Women engaged in vigorous exercise programs should be made aware that hyperthermia may have teratogenic effects (i.e. cause birth defects,especially of the brain and spinal cord known as neural tube defects)and furthermore, this potential risk is greatest during the earliest weeks of pregnancy. Mom may not even know that she is pregnant during this very vulnerable time. The following is a quote from "Preconceptual Health Care: A Practical Guide by Dr. Robert Cephalo and Merry-K Moos, MPH, two professors in the Department of Obstetrics and Gynecology, Department of Maternal Fetal Medicine at the University of NC..... "Because core temperature sensitivities during exercise appear to be individual, it is difficult to offer a generalized prescription that is appropriate for all women." However, it seems reasonable to advise the patient involved in strenuous activity regarding the potential of this strenuous activity to cause hyperthermia which could be detrimental if she is already pregnant. Also, for those who are trying to get pregnant, we really don't know the extent that the exercise induced increase in core body temperature has on fertility. In other words, the 70% heart rate guideline given by the physicians at the University of NC in the Preconceptual Counseling Program errs on the side of conservatism. You have to realize where these counselors are coming from. They "lay all the available information on the table" and then let the patient decide what she wants to do, i.e. informed consent. At 70%, we know that the potential for hyperthermia is minimized. We are not sure about those working out at 85%.
There are many other variables that affect fertility. Are your periods regular? What is your body fat percentage? Are you vegetarian? All of the above plus many more can affect fertility. Have you been to a preconception counseling visit with your OB?
Hope this better explains my original recommendations. Keep us posted on your dreams. Good luck.
Sheila Watkins
