Does Vaping While Pregnant Cause Birth Defects?

Vaping during pregnancy has not yet been definitively linked to structural birth defects in large human studies, but the picture is far from reassuring. Animal and laboratory research shows that e-cigarette aerosol can cause craniofacial defects, disrupt heart development, and impair lung formation in developing embryos. Meanwhile, human data consistently ties prenatal vaping to higher odds of low birth weight, preterm delivery, and restricted fetal growth. The gap between those two bodies of evidence reflects how young this field is, not that vaping is safe for a developing fetus.

What Animal Studies Have Found

The strongest evidence linking e-cigarette exposure to actual structural malformations comes from laboratory work on animal embryos and cell cultures. In frog embryos (a common model for studying early development), exposure to e-cigarette aerosol caused median facial clefts and underdevelopment of the midface, defects that mirror the cleft lip and palate spectrum in humans.¹ A separate study in rodents found that prenatal exposure to e-cigarette aerosol altered facial growth parameters in offspring, raising concern about craniofacial effects in mammals as well.²

Heart development is another area of concern. Frog embryos exposed to flavored e-cigarette aerosol developed smaller ventricles, reduced heart rates, and diminished blood flow to the head. Interestingly, vanillin alone, without any nicotine, reproduced the heart defects, pointing to flavoring chemicals as an independent hazard.³ In a rat model, prenatal e-cigarette exposure rewired the cardiac protein landscape of newborns in a sex-dependent way: male offspring showed disrupted energy metabolism in heart cells, while females showed problems with protein quality control and signaling pathways tied to stress resilience. By adulthood, males had impaired baseline heart function and worse outcomes after simulated heart attacks, while females had preserved resting function but heightened vulnerability to cardiac stress.⁴

Lung development has been studied in multiple rodent models. Mouse offspring exposed to maternal vaping showed reduced airspace development, suggesting either delayed lung maturation or specific disruption of how the air sacs form.⁵ Another mouse study found that prenatal vaping altered lung structure at birth by disrupting a signaling pathway essential for organ formation, with offspring showing abnormal tissue density in the lungs.⁶ A third investigation documented an emphysema-like pattern in neonatal lungs along with increased breathing workload, decreased lung compliance, and greater respiratory resistance.⁷

These studies are not proof that the same defects occur in human babies. Frog and mouse embryos are exposed to aerosol components more directly than a human fetus is, and doses do not always translate across species. But they identify plausible biological mechanisms and specific organ systems that are vulnerable, which is why researchers treat them as serious warning signals rather than curiosities.

What the Human Data Shows So Far

Large-scale human studies have not yet caught up to the laboratory findings on structural malformations. What they have established is that vaping during pregnancy is linked to a cluster of adverse outcomes that overlap heavily with the harms of conventional smoking. A 2024 meta-analysis pooling data from 23 studies and more than 900,000 participants found that prenatal vaping was associated with roughly 50% higher odds of adverse neonatal outcomes, including about 56% higher odds of low birth weight, 49% higher odds of preterm birth, and 48% higher odds of the baby being small for gestational age.⁸

These findings align with a U.S. population-based study that found e-cigarette use during pregnancy was associated with higher rates of low birth weight and preterm birth, and that the association was driven by daily users. Among women who vaped but did not also smoke traditional cigarettes, the rate of low birth weight was about 10.6% compared with 6.1% among nonusers.⁹ Another study using the same national surveillance system found that exclusive e-cigarette use was linked to higher risk of preterm birth and low birth weight, but that quitting vaping during pregnancy reduced the risk of low birth weight and small-for-gestational-age babies by roughly a quarter compared with continuing to vape.¹⁰

A systematic review that specifically looked at studies comparing exclusive vaping with complete non-use found a mixed picture: most studies did not find increased risk for individual outcomes, but birth weight and neurological outcomes stood out as areas where evidence was split, with equal numbers of studies finding harm and finding no harm.¹¹ The honest summary is that the human evidence strongly supports harm to fetal growth and gestational timing, while the jury is still out on whether vaping causes the kind of structural malformations seen in laboratory animals.

Why Nicotine Alone Is a Problem for Development

Much of the concern about vaping during pregnancy traces back to nicotine itself, regardless of how it is delivered. Nicotine crosses the placenta efficiently and reaches the fetal brain, lungs, and other developing organs. The mechanism of harm is tied to how nicotine interacts with receptors normally activated by the body’s own signaling chemicals. These receptors appear very early in embryonic development, and when nicotine activates them at the wrong time, it disrupts the normal sequence of cell growth, migration, and specialization. Researchers have found that this can lead to abnormal cell death and division errors during critical windows of brain formation.¹²

A 2025 review focused on how this early receptor disruption plays out over time found that prenatal nicotine exposure alters how neurons mature, how the immune system in the brain develops, and how stress-response systems are wired. These changes are not just temporary; they contribute to lasting vulnerability to cognitive problems, behavioral issues, and psychiatric conditions that can persist into adulthood.¹³ Animal studies have documented impaired attention, reduced short-term memory, poor object discrimination, and compromised motor coordination in offspring exposed to e-cigarette aerosol prenatally.¹⁴

This is worth emphasizing because many people think of birth defects only as visible physical abnormalities. Neurodevelopmental harm, changes in how a child’s brain is wired that affect behavior and cognition years later, is a less visible but equally real consequence. The nicotine in e-cigarettes is pharmacologically identical to the nicotine in traditional cigarettes, and decades of research on prenatal nicotine from smoking have consistently shown effects like low birth weight, increased activity levels, and cognitive impairment in offspring.¹⁵

The Flavoring Problem

One finding that surprises many people is that nicotine-free e-cigarette aerosol is not necessarily harmless to a developing embryo. Laboratory evidence shows that components of e-liquid beyond nicotine, particularly flavoring chemicals, can be toxic to developing cells on their own.¹⁶ Flavoring compounds have been found to trigger inflammation, cause cell damage, and increase levels of reactive oxygen species, which are chemically reactive molecules that can damage cells. Early pregnancy is extremely sensitive to these insults because implantation and placental development depend on a tightly controlled chemical environment.¹⁷

The flavoring question matters practically because some pregnant women switch to nicotine-free vape products thinking they have eliminated the risk. A rat study that compared nicotine-containing and nicotine-free e-cigarette aerosol found that both produced lasting arterial stiffness and impaired blood vessel relaxation in offspring, effects that persisted into adulthood. The damage was tied to oxidative stress, and it occurred regardless of whether nicotine was present.¹⁸ The cardiovascular heart-defect study mentioned earlier also found that vanillin alone, not nicotine, reproduced the cardiac abnormalities in frog embryos.³

Specific flavors may carry different levels of risk. One study using U.S. population data found that while overall vaping during pregnancy did not show a statistically significant increase in high-risk births, the use of mint or menthol flavored products was associated with more than three times the odds of fetal death.¹⁹ That finding comes from a single study with wide confidence intervals, so it is not yet definitive, but it fits the pattern that flavoring chemicals have biological effects independent of nicotine.

How Vaping Compares to Smoking During Pregnancy

About two-thirds of pregnant women in one survey believed e-cigarettes were safer than traditional cigarettes, and that perception appears to drive some of the switch to vaping during pregnancy.²⁰ E-cigarettes do eliminate exposure to tar, carbon monoxide, and thousands of combustion byproducts found in cigarette smoke, so the idea that they are less harmful than smoking is not unreasonable for non-pregnant adults. The question is whether “less harmful than smoking” means “safe enough for pregnancy,” and the answer appears to be no.

Meta-analytic data comparing vaping directly to smoking found no significant difference between the two for preterm birth or low birth weight. Vapers did have a lower risk of small-for-gestational-age babies compared with smokers and an even lower risk compared with dual users.²¹ One earlier U.S. study found that late-pregnancy vapers had similar preterm birth risk as nonusers but still had elevated risk of restricted fetal growth, with odds roughly comparable to those of smokers.²²

The takeaway from the comparative data is that vaping may carry slightly lower risk than smoking for some outcomes, but it is not a clean win, and for fetal growth restriction it performs about as poorly as cigarettes do. For a pregnant person, “better than smoking” still means “measurably worse than not using either product.”

The Dual-Use Trap

In practice, many pregnant vapers are not exclusively vaping. They are using e-cigarettes alongside conventional cigarettes, either because they are attempting to cut down on smoking or because they have added vaping on top of an existing habit. A systematic review found that dual use of e-cigarettes and cigarettes was significantly associated with increased risks of small-for-gestational-age babies, preterm birth, and lower mean birth weight compared with non-use.²³ In one survey of pregnant women, about 8.5% were using both e-cigarettes and traditional cigarettes, a higher proportion than either exclusive smoking or exclusive vaping.²⁰

This pattern matters because dual use may deliver more total nicotine and a wider range of harmful chemicals than either product alone. A separate meta-analysis underscored that dual use during pregnancy is a significant and growing health concern, with prevalence rates that warrant targeted public health interventions.²⁴ If you are pregnant and trying to quit smoking, the goal should be to get to zero nicotine and zero inhalant products, not to swap one source for another.

What the Placenta Has to Do With It

The placenta is the gatekeeper between the pregnant person’s bloodstream and the fetus, and nicotine passes through it readily. Researchers measure this by tracking cotinine, the main breakdown product of nicotine, in both maternal and fetal tissues. Nicotine exposure at the levels delivered by e-cigarettes can disrupt placental blood vessel formation, alter gene expression in the placenta, and impair the organ’s ability to support fetal growth. A scoping review tied this placental dysfunction to the cascade of outcomes seen in epidemiological studies: fetal growth restriction, preterm birth, and congenital anomalies including craniofacial defects.²⁵

The placental pathway also helps explain why nicotine-free vaping is not necessarily safe. The heating process used to aerosolize e-liquid generates aldehydes, metals, and volatile organic compounds that can cross the placenta through the same mechanisms as nicotine. Combined with the flavoring chemicals discussed earlier, this means the fetus is exposed to a cocktail of substances that are biologically active during the most sensitive periods of organ formation.

What Doctors Recommend

The American College of Obstetricians and Gynecologists advises clinicians to counsel pregnant patients to stop using all tobacco and nicotine products, including e-cigarettes, and to offer behavioral support and, when appropriate, pharmacotherapy to help with cessation.²⁶ The recommendation is total abstinence from nicotine in any form throughout pregnancy. This is not a hedged suggestion; it reflects the finding that nicotine receptors are active very early in fetal brain development and that exposure at any stage can interfere with normal growth.¹²

There is, however, an uncomfortable tension in the clinical world. Some pregnant women who smoke cannot quit with counseling alone, and a U.K. randomized trial compared e-cigarettes with nicotine patches as a cessation aid during pregnancy. Validated quit rates were low in both groups, roughly 7% for the e-cigarette arm versus about 4% for the nicotine patch arm, a difference that was not significant in the primary analysis.²⁷ Qualitative research with participants in similar programs found that women viewed e-cigarettes positively as a quit tool, but many struggled to stay quit, suggesting that access to the device alone is not enough without robust ongoing support.²⁸

For a pregnant person who is already addicted to nicotine through smoking, the calculus is genuinely difficult. If the realistic choice is between continued heavy smoking and switching to vaping because full cessation has failed repeatedly, some clinicians weigh the known harms of combustible cigarettes against the somewhat-lower but still-present harms of vaping. But that is a harm-reduction conversation between a patient and their provider, not a green light to vape during pregnancy. For someone who does not already smoke, there is no scenario where picking up a vape while pregnant is a defensible choice.

Why the Research Gap Exists

The reason we do not yet have definitive human data on structural birth defects is partly ethical and partly practical. You cannot run a randomized trial in which pregnant women are assigned to vape. Researchers rely on survey data and birth registries, which have their own limitations: women may underreport vaping, product formulations vary enormously, and separating the effects of nicotine from flavoring chemicals and solvents in a population study is extremely hard. Hair biomarker analysis, which can measure cumulative nicotine and tobacco-specific nitrosamine exposure over an entire trimester, is one tool being developed to improve exposure assessment.²⁹

There is also a conceptual issue: the perception that e-cigarettes are relatively harmless has been so pervasive that some women do not mention vaping to their healthcare providers, and some providers do not ask. One study found that the proportion of pregnant women using e-cigarettes was at least as high as the proportion smoking cigarettes, yet the public conversation about prenatal nicotine exposure still focuses overwhelmingly on traditional smoking.²⁰ That mismatch between prevalence and attention means the question is likely to be studied more rigorously in the coming years, but for now, pregnant people are making decisions with incomplete information. The strongest statement the evidence supports is this: every system researchers have looked at, the face, heart, lungs, brain, blood vessels, and placenta, shows signs of harm from prenatal e-cigarette exposure in at least some experimental model, and the human epidemiological data consistently points in the same direction even if it has not yet pinned down specific structural defects.