A new longitudinal study provides some initial evidence that preconception cannabis use is associated with an increased risk of postpartum depression. The findings have been published in the journal Drug and Alcohol Dependence.
Postpartum depression affects nearly one in five new mothers, who may experience symptoms such as mood swings, anxiety, severe fatigue, intense irritability, and difficulty bonding with their baby. Given that cannabis is one of the most widely used substances in the world, a research team in Australia looked into whether its use was a risk factor for postpartum depression.
“The legalization of cannabis use in many regions worldwide witnessed increased use and decreased perception of associated harms. Recent studies from the United States and Canada even reported significant increases in cannabis use during the preconception period in states that had legalized recreational cannabis,” explained Sifan Cao, a PhD candidate at The University of Queensland and the corresponding author of the new study.
“The Australian Capital Territory legalized personal cannabis use on January 31, 2020, so it would not be surprising to see an increase in preconception cannabis use here in the future. About 21% of young women in this study had used cannabis, despite it being illegal in Australia at the time of the surveys.”
“Previous evidence has linked cannabis use with an increased risk of depression,” Cao said. “Therefore, preconception cannabis use may be associated with a higher risk for postpartum depression; however, no previous studies have examined this. Given that postpartum depression affects about 1 in 5 women in their first year after delivery and has harmful impacts on the woman, her child, and the family, investigation of preconception cannabis use and its associations with postpartum depression will help inform possible prevention strategies.”
For their study, the researchers examined data from a cohort of 17,011 young women who were recruited for the Australian Longitudinal Study on Women’s Health in 2012 and 2013. As part of the annual survey, participants were asked if they had used cannabis in the past year.
“In Australia, women in their 20s are the most likely to use cannabis across all age groups; they also make up the most significant proportion (36.9%) of mothers,” Cao said. “Therefore, it is of greatest priority to determine whether preconception cannabis use is associated with a higher risk of postpartum depression in this age group.”
Approximately 22% of the women who gave birth during the course of the study reported that they had used cannabis 3 to 15 months before their pregnancy.
Cao and her team found that women who reported using cannabis before their pregnancy were at higher risk of suffering postpartum depression for that pregnancy. In addition, women who reported using cannabis in at least two surveys also had a higher risk of postpartum depression for births in the following years compared to those who reported no cannabis use. This was true even after controlling for sociodemographic factors (such as age and level of education), health behaviours (such as alcohol consumption), and psychological distress.
“Cannabis use before pregnancy was associated with an increased risk of postpartum depression, and the level of increased risk was dependent on the extent of cannabis exposure. Chronic use before pregnancy was associated with a higher risk of subsequent postpartum depression. The closer the cannabis use was relative to pregnancy, the higher the risk for postpartum depression,” explained Cao.
The prevalence of postpartum depression was highest among women who reported using both cannabis and tobacco prior to pregnancy, followed by those who had only used tobacco and those who had only used cannabis. The prevalence of postpartum depression was lowest among women who reported never using either substance.
“Our study was the first of its kind that investigated the links between preconception cannabis use and postpartum depression,” Cao said. “The major limitation of our study is that we had no details about the dose, frequency, or duration of preconception cannabis use. That means even one-off experimental use, if reported, would classify as having used cannabis. Also, the preconception period ranged from 3 to 15 months before pregnancy. Therefore, future studies considering the dose, frequency, and duration of cannabis use are needed to confirm our findings.”
Why cannabis use is associated with postpartum depression is also unclear. It is possible that cannabis increases the risk of postpartum depression because of its effects on the neuroendocrine system. However, it is also possible that the relationship the indirect effect of other factors. For example, women who use cannabis could be “more likely to experience adverse life events or circumstance changes that are further linked with depression,” the researchers explained.
“Current clinical recommendations encourage pregnant women or those contemplating pregnancy to discontinue cannabis use, mainly because of the adverse health consequences of continued use during pregnancy,” Cao noted. “Our findings extend the harms of cannabis use to preconception use and provide evidence for the benefits of quitting cannabis use at least 15 months before pregnancy.”
“If other studies confirmed our results, we would expect clinical recommendations to encourage cannabis cessation in the preconception period. By then, health providers could consider educating women who use cannabis during preconception consultancies on the harmful effects of cannabis use and the health benefits of quitting.”
The study, “Association between preconception cannabis use and risk of postpartum depression: Findings from an Australian longitudinal cohort“, was authored by Sifan Cao, Mark Jones, Leigh Tooth, and Gita Devi Mishra.
