The type of heparin to administer for treating thrombotic problems during pregnancy has become a debatable medical question. For years unfractionated heparin (UFH) has been the drug of choice. However, low molecular weight heparin (LMWH) has been gaining favor. Currently, the decision of which drug to use has been left up to physician preference due to the limited number of clinical trials that have been conducted during pregnancy. Methodology: A systematic review of the literature was conducted to determine whether pregnancy outcomes differ among those treated with LMWH, UFH, or both for thrombotic conditions during pregnancy. Twenty-one articles addressing LMWH, UFH, pregnancy outcomes, and thrombotic conditions in pregnancy were reviewed using evidence-based methods. Pregnancies from the first trimester through the postpartum period were included in the review. Results: After a review of the literature, it was found that LMWH is equally if not more effective in treating thrombotic conditions in pregnancy. LMWH was found to have fewer side effects and to be more convenient to administer and monitor than UFH. Conclusion: LMWH is as safe and effective as UFH for preventing and treating thrombosis in pregnancy with the added benefits of fewer side effects and convenience of administration.