The answer: Yes. Profoundly, across multiple systems, throughout every trimester. Smoking during pregnancy is one of the most significant preventable causes of pregnancy complications, infant death, and lifelong health consequences for the child.
What smoking does during pregnancy
Every cigarette a pregnant woman smokes exposes the developing fetus to over seven thousand chemicals, including nicotine, carbon monoxide, and at least seventy carcinogens through the placental circulation that connects maternal and fetal blood supply.
Carbon monoxide and oxygen deprivation. Carbon monoxide from cigarette smoke binds to fetal hemoglobin with even greater affinity than adult hemoglobin, displacing oxygen from the fetal blood supply at a critical period when oxygen delivery determines organ development. The developing brain, heart, and lungs of the fetus are chronically deprived of the oxygen they require for normal growth.
Nicotine’s vascular effects on the placenta. Nicotine constricts the placental blood vessels, reducing the blood flow through which the fetus receives oxygen, nutrients, and immune factors from the mother. A chronically constricted placental circulation produces a fetus that is consistently undernourished and underprotected throughout the pregnancy.
Direct fetal nicotine exposure. Nicotine crosses the placenta freely, reaching fetal brain tissue at concentrations that directly disrupt the developing nervous system. The fetal brain’s nicotinic acetylcholine receptors (critical for normal neural development) are persistently stimulated by maternal nicotine, producing developmental changes in the neural circuits governing breathing control, arousal, and cognitive function.
The specific harms
Miscarriage. Smoking significantly increases the risk of miscarriage through placental insufficiency, vascular compromise, and direct toxic effects on the developing embryo in the first trimester.
Ectopic pregnancy. Smoking doubles the risk of ectopic pregnancy through nicotine’s effects on fallopian tube motility and ciliary function.
Placenta previa and placental abruption. Smoking increases the risk of placenta previa (abnormal placental positioning) and placental abruption (premature separation of the placenta from the uterine wall), both of which are serious obstetric emergencies threatening maternal and fetal life.
Premature birth. Smoking significantly increases preterm birth risk through inflammatory mechanisms, cervical changes, and placental insufficiency that trigger early labor. Premature infants face elevated risks of respiratory distress, developmental delay, and lifelong health consequences.
Low birth weight. Babies born to smoking mothers are on average two hundred grams lighter than those born to non-smoking mothers, a deficit produced by chronic placental insufficiency and nutrient deprivation throughout the pregnancy. Low birth weight is independently associated with cardiovascular disease, diabetes, and cognitive impairment in adulthood.
Stillbirth. Smoking approximately doubles the risk of stillbirth through placental insufficiency, fetal hypoxia, and the direct toxic effects of tobacco compounds on fetal development.
Sudden Infant Death Syndrome (SIDS). Prenatal nicotine exposure disrupts the development of the brainstem’s arousal and respiratory control systems, producing the blunted arousal response to hypoxia that underlies SIDS. Infants born to smoking mothers have significantly elevated SIDS risk independent of postnatal secondhand smoke exposure.
Cleft lip and palate. Smoking during the first trimester (when facial structures are forming) significantly increases the risk of cleft lip and palate through the toxic effects of tobacco compounds on facial development.
Developmental and cognitive consequences. Children born to mothers who smoked during pregnancy show measurably lower cognitive scores, higher rates of ADHD, behavioral difficulties, and learning disabilities compared to children of non-smoking mothers, reflecting the direct neurodevelopmental effects of prenatal nicotine and hypoxia exposure on the developing brain.
Increased asthma and respiratory disease. Prenatal smoke exposure impairs fetal lung development, producing children with reduced lung capacity, higher rates of asthma, and greater susceptibility to respiratory infections throughout childhood and into adulthood.
Is any level of smoking safe during pregnancy?
No. There is no established safe level of smoking during pregnancy. Every cigarette exposes the fetus to carbon monoxide, nicotine, and carcinogens. Every cigarette reduces placental blood flow. The harms are dose-dependent, but the threshold below which smoking produces no harm does not exist.
Reducing smoking during pregnancy reduces harm relative to heavier smoking but does not eliminate it. Complete cessation is the only intervention that removes the smoking-related harm entirely.
NRT during pregnancy – the risk-benefit question
NRT during pregnancy (patches, gum, lozenges) delivers nicotine without the carbon monoxide, tar, and thousands of additional toxic compounds of cigarette smoke. For pregnant women who cannot achieve cessation without pharmacological support, NRT represents a harm reduction, removing the majority of smoking’s toxic burden while managing the nicotine withdrawal that prevents cessation.
The nicotine in NRT still crosses the placenta and still affects fetal development. NRT during pregnancy is not without risk. But the risk of NRT is significantly lower than the combined risk of continued smoking, making NRT a clinically defensible option for pregnant smokers who are unable to quit without support.
Varenicline and bupropion are not recommended during pregnancy; insufficient safety data exists for these medications in the context of fetal development.
Any pregnant woman seeking cessation support should discuss the full range of options (behavioral support, NRT, and clinical monitoring) with her obstetrician before the quit date.
The one thing to hold onto
Every cigarette during pregnancy is a decision made for two people- one of whom cannot consent, cannot leave, and cannot protect themselves.
The harms are real, documented, and preventable.
Cessation at any point in pregnancy produces benefits- the earlier the better, but never too late to reduce the harm that continued smoking would produce for the remainder of the pregnancy.
Cignix is India’s neural circuit-based smoking cessation platform. The Cignix Protocol works with the biology of how smoking is learned and how it is unlearned. The entry point is the Smoking Immunity Meter at learn.cignix.com/user/sim. Visit cignix.com.