Multiple Risk Factors Linked to Preemies

Marijuana during pregnancy doubles chances of delivering baby too early

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Marijuana is often thought of as a drug that causes relatively little harm compared to other street drugs. But that may not be the case if you're carrying a little one to term.

A recent study cataloged the risk factors associated with preterm birth. They found, among those factors, that using marijuana while pregnant can double the risk of giving birth to a preemie.

"Don't use marijuana while pregnant."

In a study led by Gustaaf Dekker, MD, PhD, a professor in obstetrics and gynecology at the University of Adelaide in Australia, researchers sought to identify risk factors for delivering babies before the 37th week of pregnancy.

They followed 3,234 women who were pregnant for the first time, and they were able to follow up with nearly all of them (3,184) after the women gave birth.

A total of 4.9 percent of these women - 156 women - gave birth to preemies. Based on these women, the researchers determined a number of factors associated with preterm birth.

Those who used marijuana, who had a history of vaginal bleeding or who had a mother with a history of pre-eclampsia or diabetes type 1 or 2 were more than twice as likely to have their baby before the 37th week.

The women who had a family history of babies with low birth weights were nearly six times more likely to have a preemie.

The researchers also found a number of factors linked to a woman's water breaking early, such as being very thin. Women with a body mass index (BMI) of under 20 were almost twice as likely to have a preemie. A BMI under 18.5 is considered unhealthy and underweight.

Women with mildly high blood pressure - low enough that it doesn't require treatment but higher than normal - had the greatest risk of preterm rupture of the membranes (early water break) leading to a preterm birth; their risk was ten times greater.

Those with a family history of gestational diabetes were eight times more likely to have their water break early, and those who received certain types of hormonal fertility treatment were almost four times more likely to have an early water-break.

Other lesser factors linked to early labor included having a short cervix, overall poor well-being and being Caucasian.

Other milder risk factors linked to having a woman's water break early included taking longer to conceive and a family history of miscarriage.

"Our study has found that the risk factors for both forms of preterm birth vary greatly, with a wide variety of health conditions and histories impacting on preterm birth," Dr. Dekker said.

"Better understanding the risk factors involved in preterm birth moves us another step forward in potentially developing a test - genetic or otherwise - that will help us to predict with greater accuracy the risk of preterm birth," he said. "Our ultimate aim is to safeguard the lives of babies and their health in the longer term."

The study was published July 16 in the journal PLoS ONE. The research was funded by New Enterprise Research Fund at the Foundation for Research Science and Technology, the Health Research Council, the Evelyn Bond Fund at the Auckland District Health Board Charitable Trust and the Premier's Science and Research Fund of the South Australian Government.

The authors declared no conflicts of interest.

Reviewed by: 
Review Date: 
July 19, 2012
Last Updated:
February 6, 2013