Marijuana use is now legal in several states, but a new study suggests that pregnant women should still be wary of using this drug.

Using marijuana daily during pregnancy can lead to host of issues, including an increased risk of low birth weight, low resistance to infection, decreased oxygen levels and other problems for baby, according to research published in the Journal of Maternal-Fetal and Neonatal Medicine.

For the study, researchers analyzed sonogram data from nearly 450 pregnant women who said they used marijuana daily during their pregnancy.

The researchers found that the women who used pot daily were more likely to have delayed fetal growth, which can put a baby at risk for health problems during pregnancy, delivery and after birth.

Among the health problems: low birth weight, low blood sugar, low Apgar scores and, in severe cases, stillbirth.

The size differences started to show up in the second and third trimesters, and researchers found an increase in placental vascular resistance during those trimesters, which can interrupt the flow of blood through the placenta and cause delayed growth.

Unfortunately, recent data from JAMA suggest that marijuana use during pregnancy has more than doubled over the past 15 years, with many pregnant women believing that marijuana use is safe during pregnancy.

The American College of Obstetricians and Gynecologists (ACOG) currently warns against using marijuana during pregnancy, noting that the chemicals in marijuana can reach the fetus by crossing the placenta, regardless of whether the marijuana is smoked or eaten.

The latest study doubled down on the ACOG recommendations, arguing that health care providers should counsel women about the risks of using marijuana during pregnancy.