How Does Smoking Affect Pregnancy?

By BSc, MSc (embryologist) and BA, MA (fertility counselor).
Last Update: 09/04/2015

Early sexual intercourse combined with early drug abuse and drinking in teens and youngsters have significant repercussions on pregnancy. The exposure to legal (alcohol and tobacco) and illegal drugs (cocaine, narcotics, and opiates) causes harmful effects on fetal development.

According to experts, alcohol is more damaging to the newborn than tobacco.

Below you have an index with the 3 points we are going to deal with in this article.

Effects of alcohol

Between 50-80% of children of alcoholic mothers have the following alterations: intrauterine growth retardation, microcephaly, short and turned-up nose, tight parpebral fissure, maxillary hypoplasia, and thin upper lip. Moreover, it is connected with anomalies in the limbs and spine, and with congenital heart defects.

The fetal brain is also severely affected, since it is not as developed as a normal one. The degree of damage may depend on the stage of pregnancy. However, if the alteration takes place in a critical developmental stage, the foetus will suffer serious malformations. Intellectual disabilities are present in 80-90% of the cases; children born under these circumstances have diminished brain convolutions and cerebral atrophy. Behavioral problems can also be observed, such as irritability in the lactant, hyperactivity in childhood, and psychosocial disorders during adulthood.

The effects differ depending on the trimester. The exposure to alcohol during the first trimester is associated with facial and ocular somatic anomalies. During the second and third semester, alcohol abuse is linked to hampered brain development, neurobehavioral alterations, and growth delay.

Effects of tobacco

Nearly 18% of women in developed countries smoke, whereas just 8% of women from developing countries smoke. Unfortunately, many of them smoke while pregnant. Nicotine and carbon monoxide are presumed to have negative effects on fetal development as they might reduce the amount of oxygen the baby gets. Children born from women who smoke weight on average 200 gr less.

Smoking doubles the risk of low birth weight. Low weight at birth may be a consequence of intrauterine underdevelopment, preterm delivery, or both.

Women who smoke during pregnancy also have twice the risk of developing complications in the placenta. One of the main complications is the growth of the placenta in the lower uterine segment, partially or completely covering the opening of the cervix. That problem is known as placenta previa. Other condition is the separation of the placenta from the uterine lining, known as placental abruption.

There also cases of preterm rupture of membranes in pregnant women who smoke. That may cause a preterm delivery.

The exposure to tobacco smoke in non-smoking women also has influence in the likelihood of delivering an underweight baby. Once the child is born, the exposure to the smoke of cigarettes may cause complications such as sudden infant death syndrome, bronchitis, pneumonia, or increase the risk of developing ashtma.

Women who wish to be on motherhood should be aware of the effects of these substances to avoid being exposed to them and therefore prevent the newborn from suffering any harm or damage.

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 Neus Ferrando Gilabert
Neus Ferrando Gilabert
BSc, MSc
Bachelor's Degree in Biology from the University of Valencia (UV). Postgraduate Course in Biotechnology of Human Assisted Reproduction from the Miguel Hernández University of Elche (UMH). Experience managing Embryology and Andrology Labs at Centro Médico Manzanera (Logroño, Spain). More information about Neus Ferrando Gilabert
Adapted into english by:
 Sandra Fernández
Sandra Fernández
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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