Is it true that you get spider veins if you get pregnant even young?

It is possible. Spider veins can develop with pregnancy, no matter how old you are.
Not Necessarily. Although pregnancy is the number 2 cause of varicose and spider veins, right behind hereditary and family history factors, it doesn't necessarily mean you will develop spider veins if you are pregnant. Certainly, as one continues to age, and with consecutive pregnancies, the risk continues to increase, and you will become more and more likely to develop them. Remember, that they are easily treated.
Pregnancy/ veins. Pregnancy can lead to both spider and varicose veins. This is due to several factors including the pressure of the fetus on the intra abdominal veins, hormonal changes and increased circulating volume of blood. Genetics also plays a role. Getting pregnant at an early age will not prevent spider or varicose vein formation and, in fact, will make you more prone to develop veins.