Clarissa Mercado couldn’t get out of bed.

A few weeks into her fourth pregnancy, the 33-year-old from Pittsburg felt sicker than she’d ever felt in her life. She spent her days vomiting. Smoothies with fresh ginger, crackers in the morning, even water made her throw up. And no morning sickness remedies – natural or prescription – helped.

Finally, after a second visit to the emergency room to get treatment for her symptoms, Mercado decided to try something she’d vowed she wouldn’t do while pregnant: She smoked cannabis.

“It was just instant relief,” said Mercado. “Within 3, 4 hits of me smoking that joint, I was just feeling so much better.”

Cannabis use during pregnancy is on the rise in California and across the United States. The trend mirrors increased use in the population overall as more states legalize pot for recreational purposes. An estimated 8% of women – about 1 in 12 – used cannabis during pregnancy in 2020, up from 3% in 2002.

The increase comes despite mounting evidence that marijuana may harm pregnant women and their babies, with studies tying use during pregnancy to a range of ills including preterm birth, low birth weight, anemia in mothers, and behavioral, mental health and developmental problems in children.

The CDC and major medical organizations such as the American College of Obstetricians and Gynecologists (ACOG) and American Academy of Pediatrics (AAP) uniformly recommend against cannabis use during pregnancy and while breastfeeding – whether that’s through smoking, vaping, dabbing, eating or drinking, or applying creams or lotions to the skin.

But the message gets muddied at ground level. Legalization of cannabis, decreasing stigma around its use, the perception that cannabis products are “natural,” and a lack of communication from some health care providers about marijuana’s risks during pregnancy can lead some women to conclude it’s harmless, studies show.

“The lack of trust between patients and prenatal care providers I think is unfortunate,” said Katie Woodruff, lead author of a study at UCSF and a public health social scientist at ANSIRH (Advancing New Standards in Reproductive Health) group at the university. “One of the harms on the patient side is that they turn to other sources of information, so they’re going online. … I can tell you if you spend five minutes googling, you will find (inaccurate commentary) saying ‘it’s fantastic, it’s great, it’ll make your baby mellow, it’ll make your baby not too big at delivery.’ There’s a lot of misinformation.”

Even if women do talk to a medical provider about cannabis during pregnancy, they may not receive the right information or support, Woodruff and her team found. In interviews with more than 30 pregnant and postpartum women who used cannabis during pregnancy, they discovered that those who did talk with their doctors about it got a range of messages, from outright approval to legal threats.

Woodruff said she’s now interviewing medical providers for a separate study and their responses so far seem to back up the women’s experiences, with some doctors saying they’re confused about the evidence on marijuana during pregnancy, or they’re unsure how to address the issue with their patients.

Meanwhile, cannabis dispensaries may be adding to the confusion. One Colorado study found that 70 percent of the state’s dispensaries in 2018 recommended marijuana products to treat morning sickness. There is no evidence that marijuana helps with morning sickness, according to ACOG.

Reasons for use

People who use cannabis during pregnancy typically used it before they got pregnant, studies show. Mercado, for example, said she smoked marijuana and consumed edibles for years to help her sleep and for anxiety prior to getting pregnant. She stopped using during each of her first three pregnancies because she’d heard about the possible negative repercussions (all her children from those pregnancies are healthy, she said), but the fourth has been much harder.

She was unable to perform her job as an insurance claims adjuster and had to take leave. She felt exhausted and depressed.

“I would cry because nothing would work and I just wanted to feel normal again,” Mercado said. “I couldn’t do things around my house. I’m a super neat freak, and I couldn’t get up and wash dishes.”

Like Mercado, most women who turn to cannabis while pregnant do so for medicinal purposes. In addition to using it for morning sickness, some report that marijuana helps ease body aches. Others use it to cope with mental health conditions such as anxiety, depression and post-traumatic stress disorder.

There are alternative, federally approved treatments that pregnant women can take for these conditions. But because marijuana products are often marketed as natural, women may assume they are safer than pharmaceutical drugs, said Kelly Young-Wolff, a research scientist with Kaiser Permanente in Northern California.

Adding to the confusion is a shortage of large-scale studies and definitive data. Many studies have been small, lack a diversity of participants, or rely on old data that doesn’t account for the stronger potency of today’s cannabis products, Young-Wolff said.

While uncertainties remain, the evidence so far paints a disturbing picture. Studies have linked cannabis exposure in utero to low birth weight, preterm birth, and stillbirth, as well as increased risk of obesity in children, anxiety, attention problems, and other behavioral challenges. Scientists also know that chemicals in marijuana pass through the placenta to the developing baby and can linger in the body for days.

Yet there are many more questions for which researchers – and patients – want answers. For example, are some forms of cannabis consumption such as vaping or smoking more harmful than other forms such as using CBD oil or eating a marijuana-infused candy? What’s the difference between using a small amount of marijuana occasionally during pregnancy versus using it heavily every day? Does it make a difference in which trimester the cannabis is used?

Researchers at Kaiser Permanente in Northern California hope to answer these questions by taking advantage of a plethora of data on marijuana exposure among the health system’s 600,000 pregnant patients. According to the organization, it’s the only large system in the nation to screen all consenting patients for exposure to cannabis and other drugs when they start prenatal care, both through questionnaires and urine tests. The health system also has data on the health of the women’s children after they’re born.

With federal funding, Young-Wolff and colleague Lyndsay Avalos are collecting and analyzing data on more than 400,000 pregnant Kaiser patients and their kids screened for prenatal marijuana use between 2009 and 2020.

Young-Wolff hopes the research will help guide future public health regulations.

Laws and policies around cannabis use during pregnancy vary throughout the country. In some states, women can — and have – faced criminal prosecution for using marijuana during pregnancy, said Lindsey English, a staff attorney with National Advocates for Pregnant Women.

In California, marijuana use during pregnancy isn’t considered a criminal matter, and health care providers are not required to report pregnant women to child protective services before the child is born, said Theresa Mier, a spokesperson for the Department of Social Services. However, providers may be required to report evidence of maternal substance abuse at the time of delivery if they determine there are other signs of risk to the child.

For Mercado, there are no easy answers. She understands there may be risks to using cannabis while pregnant, but remains unconvinced it’s any less safe than taking prescription drugs.

She has talked openly with her doctor and ob-gyn about her cannabis use. Both advised her to stop, but haven’t pushed the matter, she said. Now in her third trimester and feeling better, she said she plans to quit for the remainder of her pregnancy.

But she also believes she couldn’t have survived the first part of her pregnancy without marijuana.

“I felt like I had no other option,” she said.

Claudia Boyd-Barrett reports for The Center for Health Reporting at USC’s Schaeffer Center for Health Policy and Economics. This story was supported by a grant from First 5 LA.