You're pregnant! What an exciting period in your life. Things are going nicely. You're over those bouts of morning sickness and you're feeling good - except for one thing. You can't help but worry about those ugly stretch marks that are beginning to show on your tummy.
MSNBC Today gives these possible risk factors for the development of stretch marks:

The study did find several risk factors for developing SG. These included weight gain during pregnancy (the more weight a woman gained, the more likely she was to develop stria), maternal age (the younger the patient, the more likely she was to develop the stretch marks), and family history (women with family members who had SG were more likely to also develop them). The study, however, did not find that SG development was influenced by skin type, socioeconomic status, smoking status (though smoking during pregnancy is still an absolute no-no), or the gender of the baby.

Women-Health_Guide says:

There is no sure shot remedy for stretch marks as mostly they fade after delivery. The only way to avoid stretch marks is to prevent them.

Their tips include things like massage and exercise.