There really is not set answer to this question, as every situation is different. It will be up to you and your doctor to determine the best course of action depending on your physical condition during your pregnancy as well as the circumstances of your work environment. Although many women are able to continue working until they are ready to give birth, other experience complications that require them to be off their feet, or even in the hospital, at certain points in their pregnancy.
If your job is particularly demanding, either physically strenuous or emotionally stressful, you may be advised to stop working after a certain point in the pregnancy (generally about 26 weeks) in order to prevent the possibility of preterm labor. On the other hand, if your job situation allows you to remain off your feet, and you work in a fairly relaxing and calm environment, you may feel comfortable remaining on the job until the very last minute. If you travel for work, you will most likely have to restrict your activity as you approach the third trimester.
Ultimately, you'll want to do whatever is most beneficial to you and the babies, as recommended by your doctor or midwife. Talk to your caregiver about your concerns. Establish open communication with your employer about your situation. They may be willing to work out alternatives that will allow you to continue working yet still accommodate your body's needs for extra rest and relaxation. Consider a reduced work schedule, scaling back to part-time hours or a modified work environment, so that you spend less time on your feet. Perhaps you can work from home or via the Internet.
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