Smoking and pregnancy
Encyclopedia
Tobacco smoking
Tobacco smoking
Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...

 and pregnancy
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

is related to many effects on health and reproduction, in addition to the general health effects of tobacco. A number of studies have shown that tobacco use is a significant factor in miscarriage
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...

s among pregnant smokers, and that it contributes to a number of other threats to the health of the fetus. Second-hand smoke appears to present an equal danger to the fetus, as one study noted that "heavy paternal smoking increased the risk of early pregnancy loss."

Ideally, women should not smoke before, during or after pregnancy. If this is not possible, however, the daily number of cigarettes must be reduced to a minimum to minimize the risks for both the mother and child. This is particularly important for women in undeveloped countries where breastfeeding is essential for the child’s overall nutritional status.

Smoking before pregnancy

Smoking can adversely affect the ability of individuals to conceive and bear children. It is important to examine these effects because smoking before, during and after pregnancy is not an unusual behavior amongst the general population and can have detrimental health impacts, especially among both mother and child as a result. It is reported that roughly 20% of pregnant women smoke at some point during the three months prior to conception (see fertilization) and delivery (see childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...

).

Tobacco use has been shown to cause erectile dysfunction
Erectile dysfunction
Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....

 (ED) in men. Organic causes of erectile dysfunction can include cardiovascular diseases and diabetes, neurological problems, hormonal insufficiencies and drug side effects. Nicotine and anti-depressants are the two most common drugs which interfere with erectile function and dysfunction as a result of these causes is known as “drug-induced male sexual dysfunction". There are numerous drug therapies to counteract erectile dysfunction. However, the least controversial treatment is the cessation of smoking and the use of other tobacco products.

Infertility

Smoking decreases fertility levels in both women and men. Female smokers are 60% more likely to have female infertility
Female infertility
-Causes and factors:Causes or factors of female infertility can basically be classified regarding whether they are acquired or genetic, or strictly by location.-Acquired versus genetic:...

 than female non-smokers. Male smokers also have approximately 30% higher odds of male infertility
Male infertility
Male infertility refers to the inability of a male to achieve a pregnancy in a fertile female. In humans it accounts for 40-50% of infertility. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity.-Pre-testicular...

 than male non-smokers. There is increasing evidence that the harmful products of tobacco smoking kill sperm cells.

Smoking during pregnancy

In the United States today, approximately 10% of women smoke during pregnancy (March of Dimes. 2010. Smoking During Pregnancy.) Of women who smoked during the last 3 months of pregnancy, 52% reported smoking 5 or less cigarettes per day, 27% reported smoking 6 to 10 cigarettes per day, and 21% reported smoking 11 or more cigarettes per day.
In the United States, women whose pregnancies were unintended
Unintended pregnancy
Unintended pregnancies are those in which conception was not intended by the female sexual partner. Worldwide, 38% of pregnancies were unintended in 1999 . Unintended pregnancies are the primary cause of induced abortion, resulting in about 42 million induced abortions per year...

 are 30% more likely to smoke during pregnancy than those whose pregnancies were intended.

Effects on ongoing pregnancy

Smoking during pregnancy can lead to a plethora of health risks to both the mother and the fetus. Smoking can cause
  • Early rupture of membranes
  • Placenta previa
  • Ectopic pregnancy
  • Placental abruption.

Smoking cigarettes doubles a woman's risk of developing placental problems. These conditions, as stated above, include premature rupture of membranes, placenta previa, and placental abruption.

Early rupture of membranes

Early rupture of membranes
Rupture of membranes
Rupture of membranes or amniorrhexis is a term used during pregnancy to describe a rupture of the amniotic sac. Normally, or "spontaneously", it occurs at full term at the onset of, or during, labor...

 means that the amniotic sac will rupture prematurely, and will induce labor before the baby is fully developed. Oftentimes this will not be lethal to the fetus or the mother, but it would cause severe economic stress as the premature child would have to stay in the hospital to gain health and strength to be able to sustain life on its own.

Placenta previa

Placenta previa is when the placenta implants over the opening of the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...

. Having a placenta previa is especially dangerous as the baby would not be able to be born vaginally. If it when the placenta would rupture before the baby was birthed,causing the mother to hemorrhage. Having placenta previa is an economic stress because it insists upon having a caesarean section
Caesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...

 delivery, which is more expensive and requires a longer recovery period in the hospital.

Ectopic pregnancy

An ectopic pregnancy
Ectopic pregnancy
An ectopic pregnancy, or eccysis , is a complication of pregnancy in which the embryo implants outside the uterine cavity. With rare exceptions, ectopic pregnancies are not viable. Furthermore, they are dangerous for the parent, since internal haemorrhage is a life threatening complication...

 is when the fetus implants itself outside of the uterus. This could prove fatal to the mother, and will be fatal to the fetus. The most common place for the fetus to implant is in the Fallopian Tubes. The Fallopian Tube could burst if the fetus becomes too large and is not caught in time.

Placental abruption

Finally, placental abruption
Placental abruption
Placental abruption is a complication of pregnancy, wherein the placental lining has separated from the uterus of the mother. It is the most common pathological cause of late pregnancy bleeding. In humans, it refers to the abnormal separation after 20 weeks of gestation and prior to birth...

 is the premature separation of the placenta from the attachment site. This again can cause problems to both the mother and the fetus. The mother could lose large amounts of blood and hemorrhage. The fetus could be put in distress because it cannot receive the proper amount of nutrients or oxygen, and the placental abruption could cause the fetus’ death. Babies born to women who smoke during pregnancy also have roughly 30% higher odds of being born prematurely.

Implications for the umbilical cord

Smoking can also impair the general development of the placenta. Impairing placental development is problematic because it reduces blood flow to the fetus. If the placenta is not developing fully, the umbilical cord
Umbilical cord
In placental mammals, the umbilical cord is the connecting cord from the developing embryo or fetus to the placenta...

 (which transfers oxygen and nutrients from the mother's blood to the placenta) cannot do its job fully. If the umbilical cord cannot transfer enough oxygen and nutrients to the fetus, it will not be able to fully grow and develop. These conditions can result in heavy bleeding during delivery that can endanger mother and baby, although cesarean delivery can prevent most deaths.

Pregnancy-induced hypertension

There is limited evidence that smoking reduces the incidence of pregnancy-induced hypertension
Pregnancy-induced hypertension
Gestational hypertension or pregnancy-induced hypertension is defined as the development of new arterial hypertension in a pregnant woman after 20 weeks gestation without the presence of protein in the urine.-Conditions:...

, but not when the pregnancy is with more than one baby (i.e. it has no effect on twins etc.). Smoking does, however, increase the likelihood of almost every other pregnancy-related health risk to both mother and child, and is the single most preventable cause of illness and death among mothers and infants in the developed world.

Low birthweight

Smoking nearly doubles the risk of low birthweight babies. In 2004, 11.9% of babies born to smokers had low birthweight as compared to only 7.2% of babies born to nonsmokers. More specifically, infants born to smokers weigh on average 200 grams less than infants born to women who do not smoke.
Premature and low birthweight babies face an increased risk of serious health problems as newborns have chronic lifelong disabilities such as cerebral palsy
Cerebral palsy
Cerebral palsy is an umbrella term encompassing a group of non-progressive, non-contagious motor conditions that cause physical disability in human development, chiefly in the various areas of body movement....

 (a set of motor conditions causing physical disabilities), mental retardation
Mental retardation
Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...

 and learning problems. Overall, they also face an increased risk of death.

Sudden infant death syndrome

Sudden infant death syndrome
Sudden infant death syndrome
Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes...

 (SIDS) is the sudden death of an infant that is unexplainable by the infant’s history. The death also remains unexplainable upon autopsy. Infants exposed to smoke, both during pregnancy and after birth, are found to be more at risk of SIDS due to the increased levels of nicotine often found in SIDS cases. Infants exposed to smoke during pregnancy are up to three times more likely to die of SIDS that children born to non-smoking mothers.

Withdrawal symptoms in child after birth

A 2003 study showed that babies born to mothers who smoked during pregnancy often undergo withdrawal-like symptoms similar to babies born to mothers who used illicit drugs during pregnancy. These babies tend to be more jittery and are harder to soothe than babies born to non-smokers.

Other birth defects

Birth defects associated with smoking during pregnancy
Defect Odds ratio
Odds ratio
The odds ratio is a measure of effect size, describing the strength of association or non-independence between two binary data values. It is used as a descriptive statistic, and plays an important role in logistic regression...

cardiovascular/heart defects 1.09
musculoskeletal defects 1.16
limb reduction defects 1.26
missing/extra digits  1.18
clubfoot  1.28
craniosynostosis
Craniosynostosis
Craniosynostosis is a condition in which one or more of the fibrous sutures in an infant skull prematurely fuses by ossification, thereby changing the growth pattern of the skull...

 
1.33
facial defects 1.19
eye defects 1.25
orofacial clefts  1.28
gastrointestinal defects 1.27
gastroschisis
Gastroschisis
Gastroschisis represents a congenital defect characterized by a defect in the anterior abdominal wall through which the abdominal contents freely protrude. There is no overlying sac and the size of the defect is usually less than 4 cm...

 
1.50
anal atresia  1.20
hernia
Hernia
A hernia is the protrusion of an organ or the fascia of an organ through the wall of the cavity that normally contains it. A hiatal hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm....

 
1.40
undescended testes  1.13
hypospadias
Hypospadias
Hypospadias is a birth defect of the urethra in the male that involves an abnormally placed urinary meatus...

 
0.90
skin defects 0.82
All defects combined 1.01

Smoking can also cause other birth defects, reduced birth circumference, altered brainstem development, altered lung structure, and cerebral palsy. Recently the U.S. Public Health Service reported that if all pregnant women in the United States stopped smoking, there would be an estimated 11% reduction in stillbirths and a 5% reduction in newborn deaths.

Future obesity

A recent study has proposed that maternal smoking during pregnancy can lead to future teenage obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...

. While no significant differences could be found between young teenagers with smoking mothers as compared to young teenagers with nonsmoking mothers, older teenagers with smoking mothers were found to have on average 26 percent more body fat and 33 percent more abdominal fat than similar aged teenagers with non-smoking mothers. This increase in body fat may result from the effect smoking during pregnancy, which is thought to impact fetal genetic programming in relation to obesity. While the exact mechanism for this difference is currently unknown, studies conducted on animals have indicated that nicotine may affect brain functions that deal with eating impulses and energy metabolism. These differences appear to have a significant effect on the maintenance of a healthy, normal weight. As a result of this alteration to brain functions, teenage obesity can in turn lead to a variety of health problems including diabetes (a condition in which the affected individual’s blood glucose level is too high and the body is unable to regulate it), hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

 (high blood pressure), and cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...

 (any affliction related to the heart but most commonly the thickening of arteries due to excess fat build-up).

Future smoking habits

Studies indicate that smoking during pregnancy increases the likelihood of offspring beginning to smoke at an early age.

Quitting during pregnancy

Quitting smoking at any point during pregnancy is more beneficial than continuing to smoke throughout the entire 9 months of pregnancy, especially if it is done within the first trimester (within the first 12 weeks of pregnancy). A recent study suggests, however, that women who smoke anytime during the first trimester put their fetus at a higher risk for birth defects, particularly congenital heart defects (structural defects in the heart of an infant that can hinder blood flow) than women who have never smoked. That risk only continues to increase the longer into the pregnancy a woman smokes, as well as the larger number of cigarettes she is smoking. This continued increase in risk throughout pregnancy means that it can still be beneficial for a pregnant woman to quit smoking for the remainder of her gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...

.
There are many resources to help pregnant women quit smoking such as counseling and drug therapies. For non-pregnant smokers, an often-recommended aid to quitting smoking is through the use of Nicotine replacement therapy
Nicotine replacement therapy
Nicotine replacement therapy is the remedial administration of nicotine to the body by means other than tobacco, usually as part of smoking cessation. Common forms of nicotine replacement therapy are nicotine patches and nicotine gum...

 in the form of patches, gum, inhalers, lozenges, sprays or sublingual tablets (tablets which you place under the tongue). However, it is important to note that the use of Nicotine Replacement Therapies (NRTs) is questionable for pregnant women as these treatments still deliver nicotine to the child. For some pregnant smokers, NRT might still be the most beneficial and helpful solution to quit smoking. It is important to talk to your doctor to determine the best course of action on an individual basis.

Smoking after pregnancy

Infants exposed to smoke, both during pregnancy and after birth, are found to be more at risk of sudden infant death syndrome
Sudden infant death syndrome
Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes...

 (SIDS).

Breastfeeding

If one does continue to smoke after giving birth, however, it is still more beneficial to breastfeed than to completely avoid this practice altogether. There is evidence that breastfeeding offers protection against many infectious diseases, especially diarrhea. Even in babies exposed to the harmful effects of nicotine through breast milk, the likelihood of acute respiratory illness is significantly diminished when compared to infants whose mothers smoked but were formula fed. Regardless, the benefits of breastfeeding outweigh the risks of nicotine exposure.

Passive smoking

Passive smoking
Passive smoking
Passive smoking is the inhalation of smoke, called secondhand smoke or environmental tobacco smoke , from tobacco products used by others. It occurs when tobacco smoke permeates any environment, causing its inhalation by people within that environment. Exposure to secondhand tobacco smoke causes...

 is associated with many risks to children, including, sudden infant death syndrome
Sudden infant death syndrome
Sudden infant death syndrome is marked by the sudden death of an infant that is unexpected by medical history, and remains unexplained after a thorough forensic autopsy and a detailed death scene investigation. An infant is at the highest risk for SIDS during sleep, which is why it is sometimes...

 (SIDS),, asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

, lung infections,
impaired respiratory function and slowed lung growth, Crohn's disease
Crohn's disease
Crohn's disease, also known as regional enteritis, is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract from mouth to anus, causing a wide variety of symptoms...

, learning difficulties and neurobehavioral effects, an increase in tooth decay
Dental caries
Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin that causes demineralization of the hard tissues and destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the...

, and an increased risk of middle ear infections.
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