Cannabis Use During Pregnancy: What Every Person Trying to Conceive Should Know
A person backlit in orange, smoking weed
The medical use of cannabis can be an important part of symptom management for people with chronic pain, cancer, anxiety, and other conditions. Cannabis is also used recreationally in the United States. As cannabis legalization expands across the United States, more people of reproductive age are using marijuana, including during pregnancy. But growing research reveals significant risks that every person trying to conceive or already pregnant needs to understand.
Cannabis Use in Pregnancy is More Common
According to the American College of Obstetricians and Gynecologists (ACOG), cannabis use among pregnant people ranges from 3.9% to 16%, with the highest rates occurring in the first trimester likely when one is unaware they are pregnant. Among young adults aged 19-22, usage reaches as high as 43%.
What's particularly concerning: In states with legal recreational cannabis, self-reported use during pregnancy has increased dramatically, with daily use rising most rapidly. Meanwhile, new fertility research reveals that tetrahydrocannabinol or THC concentrations in cannabis products have nearly quadrupled since 1995 from about 3% to 15% or higher.
Cannabis Reaches Your Developing Baby
Here's what happens when you use cannabis during pregnancy:
THC crosses the placenta. The main psychoactive compound in marijuana is fat-soluble and passes directly from your bloodstream to your baby. Fetal THC concentrations reach approximately 10% of maternal levels.
Cannabinoid receptors are present early. Maternal blood crosses the placenta at around 12 weeks’ gestation. Your developing baby has cannabinoid receptors as early as 5 weeks of pregnancy, when these receptors play crucial roles in brain development.
THC also accumulates in breast milk. If you're breastfeeding, THC transfers into breast milk, exposing your infant during a critical period of neurodevelopment.
Recent research found THC and its metabolites in the follicular fluid surrounding women's eggs, confirming that cannabis affects the reproductive environment before conception even occurs.
Pregnancy Complications Linked to Cannabis
Multiple studies document serious risks associated with prenatal cannabis exposure:
Immediate Pregnancy Outcomes
Low birth weight babies: Consistent association across multiple studies
Preterm birth: Increased risk of spontaneous early delivery
Small-for-gestational-age infants: Babies smaller than expected for their weeks of pregnancy
Neonate ICU admission: Higher rates of intensive care needs
Placental complications: Adverse outcomes related to placental function
Effects on Egg and Embryo Quality
The fertility study published in Nature Communications revealed that women with detectable THC in their follicular fluid had:
Significantly lower embryo euploidy rates (60% vs. 67% in controls)
Increased chromosome abnormalities in eggs (9% increase)
Abnormal spindle formation in 92% of eggs exposed to higher THC doses
These chromosomal errors can lead to failed fertilization, implantation failure, or miscarriage.
Long-Term Effects on Children
Perhaps most troubling are the potential lasting impacts on children exposed to cannabis before birth:
First Month of Life: Newborns show altered arousal patterns, regulation difficulties, and increased excitability.
Childhood and Beyond: Studies suggest increased risk of:
Attention deficit disorders
Behavioral challenges
Short-term memory problems
Intellectual disabilities
Diminished cognitive functioning in verbal reasoning, language comprehension, and executive function
Adolescence and Adulthood: Higher risk of developing substance use disorders or psychiatric disorders.
While these studies face challenges in isolating cannabis effects from other factors, the consistent pattern of neurocognitive impact is concerning.
The Mythos of “Natural” and “Safe” During Pregnancy
Many people believe cannabis is natural and therefore safe during pregnancy, especially for managing nausea. While cannabis can be effective to manage nausea in other situations, there is no safe amount of cannabis use during pregnancy. ACOG states clearly: "There are no medical indications for cannabis use during pregnancy and the postpartum period."
Cannabis products are not FDA-regulated. Studies show 23-60% of products contain inaccurately labeled cannabinoid concentrations, and one in five CBD-only products actually contained THC.
And on the other side of things, after prolonged use at larger doses, cannabis hyperemesis syndrome is real. Paradoxically, regular cannabis use can cause severe, cyclic nausea and vomiting. Quite the opposite of its intended effect.
What About Breastfeeding?
ACOG recommends against cannabis use while breastfeeding, but with an important caveat: Continued cannabis use is not a contraindication to breastfeeding, and breastfeeding should not be discouraged.
Why this nuanced position? It’s the risk to benefit ratio. The well-established benefits of breastfeeding, including decreased infection rates, lower asthma risk, reduced obesity, and improved intellectual development, must be weighed against potential cannabis exposure.
However, limited research on cannabis and lactation means we don't fully understand short-term and long-term effects on infants.
If You’re Using Cannabis
Before Pregnancy
Stop cannabis use at least 2-3 months before trying to conceive. Eggs take approximately 90 days to mature, and THC's main metabolite can remain detectable for up to 30 days after use.
During Pregnancy
Be honest with your healthcare provider about cannabis use. You deserve:
Non-judgmental care: Your provider should focus on your health, not legal consequences
Alternative treatments: Evidence-based options for nausea, anxiety, pain, or other symptoms
Support for cessation: Resources to help you stop using cannabis
Seventy-three percent of pregnant people who tested positive for THC had not disclosed their use on intake questionnaires, often due to stigma or fear of legal consequences.
Screening and Testing
ACOG recommends universal screening through interviews or validated screening tools, NOT biological testing. Drug testing should only occur with informed consent and knowledge of potential consequences.
Importantly, there are significant racial disparities in drug testing practices. Black mothers and and their newborns are 4-10 times more likely to be tested and reported to child protective services, despite similar usage rates across racial groups.
Getting Help to Quit
If you're struggling to stop cannabis use, several strategies may help:
Motivational interviewing: Work with a counselor who helps you identify personal reasons to quit without judgment.
Address underlying issues: If you're using cannabis to self-treat anxiety, depression, nausea, or pain, work with your provider to find safer alternatives. Acupuncture and other manual therapies are safe and effective options to consider.
Involve your support system: Partner and family assistance increases success rates.
Supportive mental health interventions: Cognitive behavioral therapy, motivational enhancement therapy, or coping skills training show promise.
Cannabis withdrawal is real. If you use more than 1.5g/day (inhaled) or products 2-3 times daily, you may experience withdrawal symptoms including irritability, anxiety, decreased appetite, abdominal pain, tremors, and headaches lasting up to 2 weeks.
The Bottom Line
As cannabis legalization continues and social acceptance grows, it's critical to understand that pregnancy and lactation are not the time to use marijuana, whether for medical or recreational purposes.
The research is clear:
Cannabis affects egg quality and chromosomal integrity
THC crosses the placenta and enters breast milk
Prenatal exposure is linked to low birth weight, preterm birth, and placental complications
Children may face neurodevelopmental challenges
If you're pregnant or planning to conceive, the safest choice is complete abstinence from cannabis. If you're currently using marijuana, talk to your healthcare provider about safer alternatives and support for quitting. It also has negative impacts on sperm production. Dr. Lee can collaborate with you and your healthcare team to address the pain, nausea, anxiety and depression, as well as support you quit.
References:
Cannabis impacts female fertility as evidenced by an in vitro investigation and a case-control study - Nature Communications, 2025
Cannabis Use During Pregnancy and Lactation - ACOG Clinical Consensus No. 10, October 2025