Smoking during pregnancy exposes the fetus to nicotine and other chemicals that can harm brain development, leading to potential motor control problems in infants. These issues stem from reduced oxygen, disrupted neurotransmitters, and changes in brain structures that control movement.
Cigarette smoke carries nicotine across the placenta to the fetus as early as seven weeks into pregnancy. Nicotine levels build up higher in the baby’s fluids than in the mother’s blood. This triggers vasoconstriction, or narrowing of blood vessels, which cuts down oxygen and nutrients reaching the developing brain.
The brain areas hit hardest include those handling movement and coordination. Prenatal nicotine exposure links to changes in the somatomotor network, a key system for motor control. It also alters the corpus callosum, the bridge between brain hemispheres that helps with coordinated actions. These shifts can show up right after birth and last into childhood.
Nicotine messes with neurotransmitter systems like dopamine, serotonin, and others that guide brain growth. It binds to receptors in the fetal brain, causing oxidative stress and faulty neuron connections. A result can be poorer motor skills, such as trouble with balance, grasping, or smooth movements in infants.
Studies tie maternal smoking to broader neurodevelopmental risks, including ADHD, which often involves motor control deficits like hyperactivity or clumsiness. Even nicotine patches during pregnancy raise ADHD odds in kids, pointing to nicotine itself as a culprit. While some research shows mixed results on exact causes, the pattern holds: smoking disrupts fetal brain wiring tied to movement.
Infants from smoking moms may face preterm birth or low birth weight, both risk factors for motor delays. Brain metabolism changes and reduced brain weight add to the problems. Experts note that damage can linger even if birth weight seems normal.
Quitting smoking early helps lower these risks, but any exposure during key growth windows affects motor pathways.
Sources
https://nhsjs.com/2025/impact-of-maternal-negative-behaviors-on-fetal-neurological-development-and-elevated-autism-risk/
https://en.wikipedia.org/wiki/Effects_of_nicotine_on_human_brain_development
https://www.consultant360.com/story/using-nicotine-patch-during-pregnancy-tied-higher-adhd-risk-0
https://www.healthbanks.com/PatientPortal/MyPractice.aspx?UAID=%7B69922199-D699-483E-B75F-C279F78658B3%7D&TabID=%7BX%7D&ArticleID=1757071622726
https://www.pnas.org/doi/10.1073/pnas.2405448121
