As with most elective treatments, sclerotherapy is not recommended for pregnant women. If you're pregnant or nursing, your doctor will advise you to postpone vein treatment. Not only is it safer, but it may be more effective, as well. Often, pregnant women develop spider veins and varicose veins as a result of hormonal changes that support childbirth. After your hormones return to a more regulated state, you may find that your varicose veins or spider veins naturally subside. If, after several months, they do not, you can talk to a vein specialist about appropriate treatment.