The short answer
Many people do, but check with your doctor and your airline first, and make sure your travel insurance covers pregnancy. In Marrakech, the things to plan around are the summer heat, bottled water and careful food choices, long drives on mountain roads, and activities such as a hot hammam or a balloon flight, which need a doctor's or operator's say-so.
In more detail
We are not doctors, and your own doctor's advice comes first. What we can tell you is where a Marrakech trip asks most of the body. Heat is the first thing: July and August regularly pass 38°C, so spring and autumn are far more comfortable. Hydration matters, and bottled water is easy to find everywhere.
Food care is the second. Stick to bottled water, food cooked hot, and fruit you peel yourself. Skip unpasteurised dairy from market stalls and raw salads rinsed in tap water at basic stalls.
Some activities need a clear yes first. The hammam's heat and steam are intense, and if you are pregnant it is sensible to check with the spa or your doctor before you book. Balloon operators can have rules on suitability, so check theirs. Long mountain drives on the Tizi n'Tichka road have hairpins; a private car lets you stop as often as you need.
Comprehensive travel insurance covering medical treatment is important for any trip. Marrakech has private clinics and well-stocked pharmacies. Tell us when you ask for a quote and we will keep the days shorter and the drives gentler.