Congratulations to your client!
Assuming that she is conditioned to high intensity, you may continue according to her doctor’s instructions and how she feels. You need the doctor’s clearance now that she is pregnant.
If all is still well and you keep in touch with her doctor, near the end of the first trimester, you will take more precautions.
For instance, keep her from getting overheated, do not take risks with activities that could cause a fall, do not do supine work for extended periods, avoid intense joint stress, no scuba diving, and no activities that risk trauma to the abdomen. If she wants to continue with too high of an intensity, just tell her that the lower intensity level is considered high intensity for the pregnant woman.
You can check ACSM, ACOG and ACE for guidelines with all the details.
Good luck to you and your client during this exciting time!
All pregnant women should strengthen their deepest abdominal muscle, their Transverse Abdominis, or TvA, to prevent common pregnancy related complaints and complications such as diastasis recti (abdominal separation), back pain, and pelvic instability. As an added benefit, because the TvA is the primary expulsion muscle, maintaining strength in this muscle greatly aids in the pushing phase of labor.
All of the answers provided are great! In addition to what’s already been said I just want to share my own experience w/ being pregnant & working out… I was already conditioned to high intensity exercise & my doctor told me I could continue doing what I had already been doing w/ the exception after the 1st trimester no lying flat on my back exercises. I remember a man at the gym telling me my baby would be strong b/c of my working out – at the time I thought he was being funny but sure enough my little girl came out strong & 3 yrs later still strong. She even has nice definition in her shoulders it’s awesome! After the 1st trimester was over I did a lot of mid-line cable chops for abs & let me tell you my obliques were crazy strong (lol) I also did standing cable crunches w/ the rope attachment. I’m sure my strong core played into my easy birth. I had my daughter at home w/ NO complications! With all that being said if your client has been training before pregnancy continue to train her as usual just adjusting her positioning as she moves through her trimesters!