Researchers studied pregnant women across the United States to understand how smoking affects folate levels—a crucial B vitamin for healthy pregnancy. They found that pregnant women who smoke are nearly twice as likely to have low folate levels compared to non-smokers. The study used national health data collected over 17 years and discovered that smoking accounts for about 3.6% of folate deficiency cases in pregnant women. This research suggests doctors should check folate levels in all pregnant women, especially those who smoke, and help them quit smoking while ensuring they get enough of this important vitamin.

The Quick Take

  • What they studied: Whether smoking during pregnancy is connected to low levels of folate, a B vitamin that helps babies develop properly
  • Who participated: Pregnant women in the United States whose health information was collected through national health surveys between 2003 and 2020. The study looked at different groups based on race, education level, and smoking status
  • Key finding: Pregnant women who smoke have about 1.87 times higher chances of having low folate levels compared to pregnant women who don’t smoke. This means smoking nearly doubles the risk of folate deficiency
  • What it means for you: If you’re pregnant and smoke, getting your folate levels checked is especially important. Quitting smoking and taking folate supplements (as recommended by your doctor) may help protect your baby’s health. This doesn’t mean non-smokers don’t need folate—all pregnant women should have adequate folate levels

The Research Details

This study looked at health information already collected from thousands of Americans over 17 years (2003-2020) through the National Health and Nutrition Examination Survey. Researchers compared pregnant women who smoked to those who didn’t, checking their folate levels using blood tests. They measured smoking by looking at cotinine (a chemical your body makes when you smoke) in the blood, which is more accurate than just asking people if they smoke. They used special statistical methods to account for differences in age, race, education, and other factors that might affect folate levels.

This approach is important because it uses real-world data from a large, representative group of Americans rather than a small laboratory study. By looking at actual blood test results instead of relying on people’s memories about smoking, the researchers got more accurate information. The study covered many years and different groups of people, making the findings more reliable and applicable to pregnant women across the country

This study has several strengths: it used a large national sample, measured smoking objectively through blood tests rather than self-reporting, and followed established guidelines for determining folate deficiency. However, because it’s a cross-sectional study (a snapshot in time), it shows an association between smoking and low folate but cannot prove that smoking directly causes folate deficiency. The study couldn’t account for all possible factors that might affect folate levels, such as diet quality or other health conditions

What the Results Show

Pregnant women who smoked had significantly higher rates of low folate levels compared to non-smokers. Specifically, smokers had 1.87 times the odds of having insufficient folate stores. This means if a non-smoker had a 10% chance of low folate, a smoker would have roughly an 18.7% chance. The study found that smoking accounts for approximately 3.6% of all folate deficiency cases among pregnant women in the United States. Low folate levels were particularly common among non-Hispanic Black women and those with a high school education or less, regardless of smoking status. Both smoking and folate deficiency were more prevalent in these groups, suggesting they face compounded health risks during pregnancy.

The research highlighted important disparities in both smoking rates and folate deficiency across different racial and educational groups. Non-Hispanic Black pregnant women showed higher rates of both smoking and low folate levels. Women with lower education levels also had higher rates of these conditions. These findings suggest that certain populations may need more targeted healthcare support and screening during pregnancy

This study adds to existing knowledge by being one of the first to specifically examine the connection between smoking and folate deficiency in pregnant women using a large national sample. Previous research has shown that both smoking and low folate independently increase pregnancy risks, but this study demonstrates they often occur together and that smoking may worsen folate deficiency. The findings support recommendations that pregnant women should avoid smoking and maintain adequate folate intake

Because this study looked at data from one point in time rather than following women over time, it cannot prove that smoking causes low folate—only that they’re connected. The study couldn’t measure all factors affecting folate levels, such as diet, vitamin supplements, or other health conditions. Additionally, the exact number of pregnant women studied wasn’t specified in the available information, though the data came from a nationally representative survey

The Bottom Line

All pregnant women should have their folate levels checked as part of routine prenatal care (high confidence). Pregnant women who smoke should receive additional screening for folate deficiency and be strongly encouraged to quit smoking (high confidence). Women planning pregnancy should ensure adequate folate intake through diet or supplements and avoid smoking (high confidence). Healthcare providers should offer smoking cessation support and folate supplementation as part of comprehensive prenatal care (moderate to high confidence)

This research is most important for: pregnant women who smoke or recently quit, women planning to become pregnant, healthcare providers caring for pregnant women, and public health officials developing pregnancy health programs. Women who don’t smoke should still ensure adequate folate intake, as the study shows folate deficiency occurs across all groups. This is less directly relevant to non-pregnant individuals, though the findings support general recommendations against smoking

Folate levels can improve within weeks of quitting smoking and starting supplementation, though it typically takes 2-3 months to see significant changes in red blood cell folate stores. Babies benefit most from adequate folate throughout pregnancy, especially during the first trimester when the baby’s neural tube is developing. Women should start folate supplementation before becoming pregnant if possible, as recommended by doctors

Want to Apply This Research?

  • Track daily folate intake (in micrograms) through food and supplements, aiming for 400-800 mcg daily during pregnancy. Log any smoking or nicotine use to monitor progress toward quitting. Record prenatal appointment dates and folate level test results when available
  • Set a quit-smoking goal with a specific date and use the app to track days smoke-free. Create daily reminders to take prenatal vitamins containing folate. Log folate-rich foods eaten (leafy greens, legumes, fortified cereals) to ensure adequate intake. Share progress with healthcare provider during prenatal visits
  • Weekly check-ins on smoking status and folate supplement adherence. Monthly review of folate-rich food consumption patterns. Track any pregnancy symptoms or concerns to discuss with healthcare provider. Monitor and celebrate milestones in smoking cessation journey. Prepare folate level test results for discussion at prenatal appointments

This research shows an association between smoking and low folate levels in pregnancy but does not provide personalized medical advice. All pregnant women should work with their healthcare provider to assess their individual folate status and smoking history. If you’re pregnant and smoke, talk to your doctor about smoking cessation programs and folate supplementation. This information is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your healthcare provider before making changes to your prenatal care or supplementation routine.