Personally I would not use them.

In general artificial sweeteners are supposed to be safe, but Saccharin isn’t safe (Sweet ‘N Low, Necta Sweet) during pregnancy

In fact, saccharin has been banned in some countries as an artificial sweetener. The American Dietetic Association (ADA) says that saccharin can cross the placenta and stay in the baby’s tissues, and the long-term effects, if any, are unknown.

However it’s the question if artificial sweeteners is such a healthy choice. Artificial sweeteners are typically 200 to 600 times sweeter than sugar. They stimulate your taste buds, go to your brain, affect your hormones and slow your metabolism. Both sugar and artificial sweetener are addictive.

Researchers say artificial sweeteners may interfere with the body’s natural ability to count calories based on a food’s sweetness and make people prone to overindulging in other sweet foods and beverages.

Stevia is probably the healthiest sugar substitute, followed by xylitol, erythritol, and yacon syrup. Natural sugars like maple syrup, molasses, and honey are less harmful than regular sugar and even have health benefits.

I do not use artificial sweeteners. Check with your GP/health professional for the best advice.