Taking folic acid during pregnancy is important for all mothers. A new study explored the effects of the B vitamin on babies whose mother smoked during pregnancy.

According to a clinical trial published in JAMA Pediatrics, mothers who smoked during pregnancy and took a higher daily dose of folic acid saw a positive impact on their baby’s birth size.

Pregnant women between the ages of 18 and 44 who were active smokers were enrolled in the study and were randomly assigned to two groups; the higher dose group who received 4 mg of folic acid a day and the lower dose group who received 0.8 mg of folic acid a day.

The study found that the women in the higher dose group had babies that weighed an average of 140 g more than the infants born to women in the standard group. These babies also had a 31% reduced risk for being small for gestational age and were 35% less likely to have fetal growth restriction.

Low birth weight isn’t the only health concern for children of women who smoke during their pregnancy. There is also an increased risk forpreterm birth, birth defects like cleft lip and palate, and sudden infant death syndrome (SIDS), according to the Centers for Disease Control and Prevention (CDC).

All women are advised to give up smoking one to three months before becoming pregnant. They are also advised to make folic acid a part of their daily regimen early to take advantage of the full effects of the B vitamin during pregnancy.