New Study Highlights the Dangers of Smoking During Pregnancy

Woman sitting on a couch holding her pregnant belly

AsiaVision / Getty

Key Takeaways

  • There is an increased rate of preterm birth, preterm premature rupture of membranes, and small for gestational age neonates in pregnant women who smoked.
  • The risk of preeclampsia was lower in women who smoked, most likely due to smaller birth weight.
  • Smoking during pregnancy could not only harm the baby, but the mother as well.

A new study published in the Journal of Perinatal Medicine found that there is a distinct correlation between smoking and pregnancy outcomes. The retrospective population-based study, which included over nine million births over 10 years, found both positive and negative effects of smoking while pregnant.

The authors of the study noted that several smaller studies had been done over the years to look at possible outcomes of smoking while pregnant but none had been done on this scale. And though the findings provided the expected results, there is still more to understand about how smoking affects a pregnant person's body. Here is what you need to know.

The Study Findings

This study looked at 9,096,788 births between 2004 and 2014 through the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample. Within this sampling, 443,590 (or 4.8%) were smokers. Researchers also used a control group of pregnant women who did not smoke during their pregnancy.

The aim was to examine the correlation between smoking and preterm birth, intrauterine growth restriction, placental abruption, and perinatal death. The study noted that smaller studies had previously been done that corroborated the belief that smoking increased the risk of these concerns but decreased the risk of preeclampsia and postpartum hemorrhaging.

Findings of this study showed an increased rate of preterm birth, preterm premature rupture of membranes, and small for gestational age neonates in pregnant women who smoked. However, the findings also showed a decreased risk of preeclampsia, chorioamnionitis, postpartum hemorrhaging, and operative vaginal delivery. 

Ido Feferkorn, MD, an author of this study and a doctor in the division of reproductive endocrinology and infertility at McGill University Health Care Center in Montreal, Canada, said the latter conclusion is one that still needs further research. “We found reduced rates of operative vaginal delivery and postpartum hemorrhage among the smokers," Dr. Feferkorn said. "It is interesting to further study this association and understand the pathophysiology behind this finding.” 

After reviewing the study, Yvonne Bohn, MD, an OB/GYN at Providence Saint John’s Health Center in Santa Monica, noted that smaller babies typically have shorter labors. “I think the reasons for these outcomes are because women who smoke have babies that are smaller and [deliver] earlier," she says. "[This means the] risk for prolonged labor that leads to hemorrhage and infection is less. Also, the risk of preeclampsia increases as women go past their due date, which is not happening for most women who smoke,” she adds. However, despite the decreased risk of preeclampsia, the concerns related to smoking while pregnant outweigh this small positive.

Dr. Feferkorn added that if research on this topic continued, smoking cessation would be something to consider. “In the non-pregnant population, we know that some adverse consequences of smoking are somewhat reversible while others are not," he says. "It would be interesting to study the relationship between the length of time prior to pregnancy that a woman stopped smoking and pregnancy complications, especially regarding long term fetal complications.”

Why Pregnant People Should Avoid Smoking

Smoking is bad for everyone, let alone a pregnant woman growing a baby. “Smoking cigarettes puts all kinds of stress on a woman’s system," says Yen Tran, DO, an OB/GYN at MemorialCare Orange Coast Medical Center in Fountain Valley, California. "When you add the changes that come with pregnancy, particularly the changes to their circulatory system, it increases the risks of bad outcomes."

One of those outcomes is the smaller birth weight. This is caused by low oxygen supply from smoking, which can also result in a decreased risk of preeclampsia. That low birth weight, though, can lead to underdeveloped limbs and organs, according to Dr. Tran. 

In addition to what the study published about the major birth-related concerns from smoking while pregnant, Dr. Feferkorn noted that issues extended to the mothers as well. “[Among the smokers,] an increased risk of wound complications and the need for hysterectomy was found,” Feferkorn said.

Tips for Quitting Smoking

For people who smoke, the most important thing to do when you get pregnant is to let your doctor know that you have a history of smoking. Your doctor will not only be able to help you quit, or at least pause while pregnant, but will also figure this into your birthing plan.

Yen Tran, OB/GYN

Physicians are aware that they cannot convince everyone to quit smoking. But, they can lend a helping hand, either to quit, cut back, or find other ways to improve overall health so that the baby is more likely to be born healthy and on time.

— Yen Tran, OB/GYN

“We know life is stressful, and we know that being pregnant is stressful,” Dr. Tran said. “Physicians are aware that they cannot convince everyone to quit smoking. But they can lend a helping hand, either to quit, cut back, or find other ways to improve overall health so that the baby is more likely to be born healthy and on time.”

The CDC’s guide to quit smoking recommends understanding why you want to quit, and your unborn baby should surely be one of those reasons. From there, you can create a plan to quit by making sure your loved ones know your plan and will support you.

Quitting smoking isn’t easy, but doing things like finding a healthier habit (like exercise), rewarding yourself for success, and channeling your energy elsewhere can help you put smoking in the past. And though it will be tempting to pick up smoking again after you give birth, maintaining the healthy habits you started while pregnant will help you resist the urges. But if you slip up, give yourself some grace and do your best to readjust.

What This Means for You

Though the study found that smoking while pregnant had its extreme negatives and minor positives, medical professionals don’t recommend smoking while pregnant. It can lead to major problems not only during birth but also to long-term side effects.

For those who smoked before getting pregnant, pregnancy is a good time to quit for the sake of your baby. And though it will be hard to stay away from cigarettes after the baby is born, it is better for your health and your child’s health to remain cigarette-free.

Was this page helpful?
3 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Feferkorn I, Badeghiesh A, Baghlaf H, Dahan MH. The relation between cigarette smoking with delivery outcomes. An evaluation of a database of more than nine million deliveries. Journal of Perinatal Medicine. 2021;0(0). doi:10.1515/jpm-2021-0053

  2. Ko T-J, Tsai L-Y, Chu L-C, et al. Parental smoking during pregnancy and its association with low birth weight, small for gestational age, and preterm birth offspring: A birth cohort study. Pediatrics & Neonatology. 2014;55(1). doi:10.1016/j.pedneo.2013.05.005

  3. Avşar TS, McLeod H, Jackson L. Health outcomes of smoking during pregnancy and the postpartum period: an umbrella review. BMC Pregnancy and Childbirth. 2021;21(1). doi:10.1186/s12884-021-03729-1