Licorice in the highly concentrated form taken in high amounts could "potentially" cause pre-term labor.
Please know that a normal, healthy person without a high risk pregnancy is not as at risk as someone with a high risk pregnancy.
Same as orgasm during pregnancy...unless you are high risk for pre-term labor there is nothing to worry about.
On a good note, black licorice is great for digestion and stomach alments...like reflux! YUCK!