Is it safe to vape if you are a female carrying a baby. Is it safe or is it not safe?
No, it's not safe. Nothing is safe.
Can we quantify the risk? Probably not. We know smoking during pregnancy is not good, but we don't know how much of the ill effect is due to nicotine vs. other substances in the smoke that aren't present in vapor such as carbon monoxide (just to name one). Moreover, I'm not aware of any studies that compare the risk of smoking with vaping with doing neither during pregnancy.
Digression:
In 1992, when my wife (a never-smoker) was pregnant with our son, the conventional wisdom was that coffee and caffeine were quite bad and pregnant women should stop consuming them. So my wife did just that, which was anything but pleasant for her.
Five years later, in 1997, when she was pregnant with our daughter, the advice had changed to, "Don't drink a whole pot every day, but there's nothing wrong with having one cup in the morning." Since she had resumed drinking coffee the moment our son was born, my wife was very happy about that.
Interestingly enough, my son (who was not exposed to caffeine in utero) doesn't consume it in any form, but my daughter (who was) started drinking coffee in her late teens and her motto is, "Death before Decaf!"
I have often wondered if exposure to "addictive" substances in the womb increases the tendency to become addicted to those same substances later in life.