Pregnant women who use mosquito coils for one night generally will not cause malformation, but in a few cases may cause fetal malformation. If a pregnant woman is pregnant for a long time, for example, has reached the late stages of pregnancy, the fetus has basically developed, although the whole night is using mosquito coils, but generally will not cause fetal malformation. If the amount of mosquito coils used by the pregnant woman is relatively small, the concentration of smoke inhaled is also very low, the impact on the fetus is also very small, and generally will not cause fetal malformation. In the first trimester of pregnancy, fetal tissue and organ differentiation has not been completed, if the pregnant woman inhaled a high concentration of mosquito smoke throughout the night, it may lead to fetal malformation, and may lead to the occurrence of miscarriage.