Premature births linked to cannabis

The danger of giving birth prematurely is twice as likely among first-time mothers who smoke cannabis prior to getting pregnant, a new study has found.

The risk rises significantly among women who continue to use marijuana throughout their pregnancies: They are five times more likely to give birth ahead of time.

The fact that some women smoke cannabis in pregnancy, often in an effort to quell morning sickness, is of grave concern, given the consequences for baby of pre-term birth, the study’s lead investigator, Cork-based Louise Kenny, has warned.

“One of the worrying things we saw in this study was that some women reported using marijuana to help with morning sickness,” said Prof Kenny. “It is important that mums know the kind of impact this can have: Being born early can have long-term consequences for your baby.”

Almost 1,600 first-time low-risk mothers attending Cork University Maternity Hospital (CUMH) took part in the Irish arm of the SCOPE study which involves 5,700 women globally.

Prof Kenny said the numbers in Ireland who reported using cannabis were “relatively small” and “less than in Australia and New Zealand” who, along with the UK, participated in the research.

“Even though the figures are small, there is a significant association with preterm birth,” Prof Kenny said.

Prof Kenny, director of the the Irish Centre for Fetal and Neonatal Translational Research, said the researchers are hopeful their work will improve outcomes for expectant mothers and their babies, and encourage them to speak to doctors if they are using marijuana.

The findings, linking cannabis use with spontaneous pre-term birth (delivering the baby before 37 weeks’ gestation) are to be published in ‘Reproductive Toxicology’ (www.sciencedirect.com/science/article/pii/S0890623816300715) on Monday.

The longitudinal study has previously measured alcohol use during pregnancy and found Ireland had the highest proportion of women drinking while pregnant, with 80% of women consuming alcohol at some point in their pregnancy, compared to 65% in the UK, 38% in Australia, and 53% in New Zealand.

Problems posed by premature birth can range from difficulties feeding to immature lungs to brain damage.