Many teens may not be getting the message about the risks of using alcohol and other drugs during pregnancy -- but that having involved parents and being engaged academically can help.

Researchers at the University of Texas at Austin examined the relationship between substance use and teen pregnancy using a large, nationally representative sample. They found that teens are less likely to abuse alcohol and drugs if they had involved parents and were engaged academically.

"We found that the odds of substance use were roughly 50 percent lower among pregnant teens reporting consistent parental support and limit-setting, as well as those who expressed strong positive feelings about going to school," Michael G. Vaughn, co-author of the study, said in a statement. "This suggests that it makes sense to engage both parents and teachers in efforts to address substance use among pregnant teens."

Nearly three in five pregnant teens reported having used one or more substances in the previous 12 months, a rate that is nearly two times as great as that of nonpregnant teens.

Additionally, the study suggests that use of these substances continues during pregnancy for many teens, particularly younger ones. More than one third of all pregnant adolescents ages 12-14 reported having used one or more substances during the previous 30 days. The substance use, however, decreases dramatically for all pregnant youths as they progress from the first into the second and third trimesters of pregnancy, according to the study. The most commonly used substance is alcohol (16 percent), followed closely by cannabis (14 percent), and finally other illicit drugs (5 percent).

"To our knowledge, this is the largest study to date on the relationship between substance use and teen pregnancy," Christopher Salas-Wright, who led the study, said in a statement. "Mothers' substance use during pregnancy can have important consequences for the health and development of newborn babies. Despite efforts to prevent substance use among pregnant teens, our findings suggest that we still have a lot of work to do."

The findings are detailed in the journal Addictive Behaviors.