I have some personal experience here of losing weight and being pregnant and I would say 1500 is on the low side if you are significantly overweight (e.g. BMI 30+) but fine if you're only a little overweight (e.g. BMI 25+) - just as very rough guides, you'll know your body and where you're currently at best. I say that because if you're much bigger it will take more energy just moving around and living day-to-day.
But! Do not get obsessed with it. Listen to your body. I know how calorie counting gets, and it's fine as a basis for food planning but you can't let it get in your head and ignore your hunger or make you feel 'bad' if you go over.
While pregnant you will have times when you are ravenous (even while feeling nauseous!) and you must listen to that. The MOST important thing is that the baby gets the nutrition it needs, even if that's lots of food one day and less another. I ate loads in my first trimester and have little appetite in my third, it really varies.
I would suggest, if you're open to it, focusing on nutrition rather than calories. That's been my most successful way of losing weight (and I lost nearly 100 lbs doing it). Eat as much nutrient dense food as you feel you need - by which I don't just mean salads and veg, but healthy proteins and fats, like houmous and avocado, and full fats, and meat and fish. I used to avoid these things as too high in calories but that's not actually healthy. Don't think of calories being bad, but as being full of the energy your baby needs - but try to focus on calories that give you nutrition rather than 'empty' calories that don't (e.g. crisps and junk).
You'll find as you progress in the pregnancy that you have to take it easy on yourself sometimes and go with what the baby needs. Listen to how you're feeling and eat and act accordingly. Sometimes you will just be exhausted and need nourishment. You can lose weight safely while pregnant but not if you go to extremes, and only if it feels good to you.
I hope that helps x