American Academy of Pediatrics National Conference and Exhibition

American Academy of Pediatrics National Conference and Exhibition


Press Release

Disclosures: The authors report no relevant financial disclosures.
October 11, 2021
2 min read

Breast milk from THC-positive mothers does not impact preterm infants in short term


Press Release

Disclosures: The authors report no relevant financial disclosures.
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Preterm infants who consume breast milk from mothers who have tested positive for THC do not experience any short-term health effects, although the long-term health effects remain uncertain, researchers reported.

“Providing breast milk from THC-positive women to preterm infants remains controversial since long-term effects of this exposure are unknown,” Natalie L. Davis, MD, MMSc, associate professor of pediatrics at the University of Maryland School of Medicine, said in a press release from the AAP.

Natalie L. Davis

“For this reason, we continue to strongly recommend that women avoid marijuana use while pregnant and while nursing their babies. Our study, however, did provide some reassuring news in terms of short-term health effects. It definitely indicates that more research is needed in this area to help provide women and doctors with further guidance,” said Davis, who also is an attending neonatologist at the University of Maryland Children’s Hospital.

The researchers analyzed the medical records of 763 preterm infants (< 34 weeks gestational age) born between 2014 and 2020 and admitted to the University of Maryland Children’s Hospital NICU. The hospital conducts universal urine toxicology and substance use screens on mothers who are admitted to labor and delivery, and 17% of these mothers (n = 130) tested positive for THC at the time of delivery.

Many NICUs restrict the use of breast milk from THC-positive women because THC passes through it, and its effects on early preterm infants are unknown. But the researchers said their hospital does not restrict breast milk use based on THC status since breast milk is one of the best ways to improve outcomes for preterm babies, yielding fewer infections and intestinal issues, improved brain growth and better overall development compared with formula.

The researchers then compared early preterm infants who were fed breast milk from THC-positive mothers with those who were fed formula or breast milk from THC-negative mothers. The results, presented at the AAP National Conference & Exhibition, showed no differences in breathing difficulties, lung development, feeding issues or other short-term health impacts.

Specifically, the researchers found no significant differences in growth restriction, oxygen requirement at 36 weeks, necrotizing enterocolitis, ventilator requirement or tracheostomy requirement.

Infants who were exposed to THC saw an increased incidence of all-grade intraventricular hemorrhage (IVH; P = .0015), the researchers said, but the largest incidence overall and specifically of grade 3/4 IVH was in infants exposed to THC who did not consume their mother’s breast milk.

After performing logistic regression and controlling for birth weight and other variables in early preterm babies, the researchers found that THC status and breast milk status did not significantly predict IVH in early preterm babies. Antenatal steroids, delivery mode and gestational age at birth were the only significant predictors.

Early preterm babies born to mothers who tested positive for THC at delivery were similarly healthy by the time of their discharge when they were fed their mother’s breast milk compared with those who did not receive their mother’s breast milk.

Additionally, mothers who tested positive for THC were more likely to be late to prenatal care (P < .0001). Mothers who did not provide breast milk were more likely to miss prenatal care as well (P < .0001).

“Teasing out the effects of THC can be very difficult to study,” said Davis. “We found that women who screened positive for THC were frequently late to obtain prenatal care, which can have a detrimental effect on their baby separate from marijuana use. This is important to note for future public health interventions.”

The researchers concluded that a better understanding of longer term perinatal outcomes associated with THC exposure both before and after birth would inform appropriate interventions to improve clinical outcomes and safely encourage breast milk provision for early preterm infants.


Davis NL. Maternal marijuana use during pregnancy and breastfeeding: Assessing in-hospital outcomes of early preterm infants. Presented at: American Academy of Pediatrics National Conference & Exhibition; Oct. 8-12, 2021 (virtual meeting).