If you have an orgasm during pregnancy, it will not affect the fetus if it happens only once in a while, but if you have frequent sex and frequent orgasms, it will probably lead to intrauterine hypoxia and possibly fetal death, so you should not have sex during the first and second trimesters of pregnancy. In the middle of pregnancy can have sex, but the frequency of sex must not be too much, to avoid frequent contractions of the uterus and cause intrauterine hypoxia, or due to the rough action of sex, resulting in contraction of the uterus and cause the placenta and uterine wall abruption, resulting in serious situations, such as fetal death in the uterus or haemorrhage, endangering the life of the pregnant woman. So even if you have sex during pregnancy, you must be gentle.