Tags: cannabis, marijuana, pregnancy loss, time to pregnancy, fecundability, live birth, LH, FSH, anovulation

 

Thumbnail: This study looked at whether cannabis use prior to conception is associated with fecundity, live birth and pregnancy loss. Following women who were trying to conceive, their cannabis use was tracked through pregnancy and birth to look for any association between cannabis use and conception and/or birth outcomes. The authors found that preconception cannabis use was associated with reduced fecundability.

 

The problem: Cannabis use continues to increase but we don’t know very much about how safe it is during the critical windows of time that pregnancy is established. Some existing studies suggest that cannabis use is not associated with fecundability, but these studies are based on self-reported cannabis use, and self-reporting may not always be reliable.

 

The study: This study followed 1,228 women with a history of pregnancy loss who were trying to conceive, and monitored their cannabis use through self-reporting at baseline and urine testing afterwards. In addition, women reported frequency of intercourse and urine samples were also used to measure reproductive hormones (and identify early pregnancy loss. The women were followed for up to 6 menstrual cycles while they were trying to conceive and throughout pregnancy. Time to pregnancy, incidence of live birth and pregnancy loss were recorded and fecundability odds ratio were calculated. Sociodemographic and lifestyle characteristics were compared among those who did and did not use cannabis, and were factored into calculations.

 

Main Points:

• Overall, 5% (62/1228) women used cannabis during the preconception period

• More than 50% of participants with positive urine tests did not self-report use

• Of the women who became pregnant, 1.3% used cannabis during their first 8 weeks of pregnancy

• 42% (26/62) women who used cannabis any time before conception became pregnant

• Self-reported cannabis use was associated with a 42% reduction in fecundability; cannabis use determined by urine test was associated with a 47% reduction.

• Cannabis use during preconception was associated with increased intercourse per menstrual cycle, higher LH levels and higher LH:LSH ratio.

• Cannabis use was suggestive of anovulation, but the association was not statistically significant

• Similar impairments were found when considering cannabis use in the 12 months preceding pregnancy, suggesting that past use may influence fecundability, which may not be immediately reversible.

• There were no associations between cannabis use during preconception and pregnancy loss.

 

Conclusions: Despite the perception that recreational cannabis use is harmless, this study found that, among women with a history of pregnancy loss, cannabis use was associated with impaired fecundability and increased frequency of intercourse.

 

Why this is a good study:

• This study took into consideration that other variables might effect reproduction and excluded women who reported smoking, alcohol or other drug use.

• This study incorporates urine testing, in addition to self-reporting cannabis use, to account for potential under-reporting when relying solely on self-reporting.

 

Why this isn’t a perfect study:

• There were relatively few cannabis users among the sample population, which limited the ability to draw conclusions about the relationship between live birth and pregnancy loss, and cannabis use.

• This study did not survey male partner cannabis use, so it was unable to account for any effects from that.

• There were a relatively small number of cannabis users in the sample, which limits the power of the conclusions.

 

What this study adds:

• It also suggests that more evidence is needed to fully understand the effects of cannabis use on reproductive health

• This study incorporates longitudinal monitoring through regular urine testing, in addition to self-reporting

 

What it doesn’t:

• The authors were unable to estimate any association between cannabis use during early pregnancy and pregnancy loss, due to the limited sample size.

• This study adds nothing about the effects that male partner cannabis use may have on reproduction.

 

Funder:

• This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contract numbers: HHSN267200603423, HHSN267200603424, HHSN267200603426, HHSN275201300023I).

• Jeannie G. Radoc has been funded by the National Institutes of Health Medical Research Scholars Program, a public–private partnership supported jointly by the National Institutes of Health and generous contributions to the Foundation for the National Institutes of Health from the Doris Duke Charitable Foundation (DDCF Grant # 2014194), Genentech, Elsevier, and other private donors..

 

Author conflicts: The authors report no conflict of interest in this work and have nothing to disclose