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EFFECTS OF SMOKING DURING PREGNANCY AND

THE EFFECTS ON THE PEDIATRIC PATIENT.

Rachel Alcorn

Laura Wooldridge

AHEC Community Project

May 25, 2007

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TABLE OF CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . pg. 3

Effects of smoking during pregnancy. . . . . . . . pg. 3

Toxic chemicals of smoking . . . . . . . . . . . . pg. 5

Infertility. . . . . . . . . . . . . . . . . . . . pg. 6

Malformations of the embryo. . . . . . . . . . . . pg. 7

Spontaneous abortion . . . . . . . . . . . . . . . pg. 7

Placenta previa-accreta. . . . . . . . . . . . . . pg. 8

Placenta abruptio. . . . . . . . . . . . . . . . . pg. 9

Growth restriction and SGA . . . . . . . . . . . . pg. 9

Ectopic pregnancy. . . . . . . . . . . . . . . . . pg. 10

Stillbirth and infant mortality. . . . . . . . . . pg. 11

Maternal smoking and the pediatric patient . . . . pg. 12

Maternal smoking and low birth weight. . . . . . . pg. 12

Risk of cleft lip and palate deformity . . . . . . pg. 13

Nicotine withdrawal and the newborn. . . . . . . . pg. 14

Sudden infant death syndrome . . . . . . . . . . . pg. 15

Smoking as a cause of asthma . . . . . . . . . . . pg. 17

Attention-deficit/hyperactivity disorder . . . . . pg. 19

Smoking cessation in the pregnant patient. . . . . pg. 20

Conclusion . . . . . . . . . . . . . . . . . . . . pg. 21

References . . . . . . . . . . . . . . . . . . . . pg. 22

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INTRODUCTION

Approximately 17.6 percent of women between the ages

of 15 and 44 years old smoked during their pregnancy last

year as stated by the Centers for Disease Control (CDC,

2007). Our purpose in this paper is to discuss the major

effects of smoking tobacco during pregnancy and in the

pediatric patient to show the importance of smoking

cessation. In this paper we aim to show in detail how

smoking during pregnancy affects the pathological

development of the fetus, the effects of the fetus itself,

as well as the long-term effects on the newborn and the

child. We will also discuss how to safely quit smoking

during pregnancy and some of the benefits of smoking

cessation on pregnancy and childhood outcomes.

EFFECTS OF SMOKING DURING PREGNANCY

It has long been known that smoking is bad for your

health, but when you add a growing fetus to the picture the

risks related to tobacco use increase tremendously. One

study states that 27.2 percent of women of reproductive age

are smoking. It is proposed that the side effects of

smoking are dose-related, meaning the more cigarettes

smoked daily the higher the risk, however any amount of

smoking will raise the probability of complications

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occurring during and after pregnancy. In addition to the

commonly studied side effects of lung disease and bladder

cancer, cigarettes can have devastating effects on a

pregnant mother and her baby. The compounds in cigarettes

have been found to decrease the fertility of men and women

making it harder to conceive. The chemicals also have a

profound effect on a growing baby; it has been proven that

smoking causes structural and vascular defects leading to

spontaneous abortion, placental and fallopian tube changes,

intrauterine growth restriction (IUGR) and premature

rupture of membranes (PROM). Women who choose to smoke

during pregnancy are taking a chance with two lives and

should be encouraged to quit or at least cut back

significantly during their pregnancies (Hammoud, et al.

2005).

Numerous studies have shown that the amount of

cigarettes smoked greatly increases the risk of side

effects to the mother and the baby. A study found that the

rate of preterm delivery in smokers increased from 6.9

percent in women who smoked up to 5 cigarettes daily to 8.9

percent in women who smoked more than 10 cigarettes daily.

This trend remains true for IUGR, APGAR scores and PROM.

For this reason if the patient is unwilling or unable to

quit, it is important to stress the need for them to reduce

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the number of cigarettes smoked on a daily basis (Hammoud,

et al. 2005).

TOXIC CHEMICALS OF SMOKING

Smoking is toxic to a growing baby due to the

various compounds found in cigarettes. The most toxic

chemicals are carbon monoxide, nicotine, cyanide as well as

89 carcinogens. Of the 89 carcinogens some of the common

ones include arsenic, benzene, cadmium, chloroform,

formaldehyde, lead, styrene and urethane. These substances

have been studied and found to cause various cancers and

fetal malformations.

Carbon monoxide attaches more readily to hemoglobin

and myoglobin than oxygen which decreases the amount of

circulating oxygen, as well as stored oxygen, in the body.

Decreased oxygen delivery to the fetus causes hypoxia which

then inhibits proper growth and development of the fetus.

Nicotine easily crosses the placenta and actually reaches

levels 15 percent higher in the amniotic fluid and fetus

than the mother experiences. With levels of nicotine being

increased in the fetus a newborn baby actually experiences

nicotine withdrawal.

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abnormalities in their sperm as a result of smoking

(American Society for Reproductive Medicine, 2003).

MALFORMATIONS OF THE EMBRYO

Harmful environmental stimuli are most detrimental

during the organogenesis stages of pregnancy. Nicotine is

a major teratogen that can severely impair proper growth

of the embryo because it accumulates in fetal blood and in

the amniotic fluid. It has been postulated that nicotine

causes cell death in the embryo resulting in spontaneous

abortion or fetal malformations. The mechanism of nicotine

on the cells leads to oxidative stress which is a major

factor in programmed cell death. Therefore, nicotine is

causing apoptosis in embryonic cells. When embryos are

exposed to 3M of nicotine they develop neural tube

defects and have shorter crown-rump lengths. The effects

are more pronounced with increased amounts of nicotine

exposure, which confirms other studies of dose-related

effects of nicotine (Zhao, 2005).

SPONTANEOUS ABORTION

Spontaneous abortion is a result of the embryo not

implanting or growing properly in the uterus. Smoking has

serious vascular effects on the uterus that cause

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vasoconstriction of the vessels. The main structural

changes in the placenta involve the villous capillaries.

The capillaries become tortuous and poorly branched which

impedes blood flow and nutrient delivery to the fetus. In

addition, vasoconstriction reduces blood flow to the uterus

and placenta. Without blood the fetus is unable to get the

proper nutrients to grow, which can lead to a spontaneous

abortion. Decreased blood flow to the placenta actually

causes hypertrophy of the placenta as a compensatory

mechanism. The trophoblastic basal lamina of the placenta

will thicken while the fetal capillaries are reduced in

size. The enlarged placenta grows enough to cover the

internal cervical os resulting in placenta previa. Another

complication to the placenta is peripheral necrosis due to

the decreased blood flow. Necrosis of the outer tissue will

weaken the walls of the placenta and may result in an

abruption. Other structural changes include increased

calcifications and fibrin deposits in placentas exposed to

smoke (Van Meurs, 1999).

PLACENTA PREVIA - ACCRETA

Placenta previa is a condition that occurs late in

pregnancy. The placenta implants too close to the cervical

os and can partially or completely cover the cervical os.

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Placenta accreta is a condition of the placenta attaching

too deeply to the uterine wall but does not penetrate the

uterine muscles. It is common to have both placenta previa

and accreta occurring at the same time. Both conditions may

result in third trimester bleeding, preterm delivery and

death to fetus and mother. The risks of developing either

condition increases with smoking during pregnancy. The

incidence of placenta accreta was 12.2 percent compared to

4.8 percent in nonsmokers due to the hypertrophy of the

placenta. The risk of placenta previa and accreta increases

with each subsequent pregnancy because of scarring which

leads to fewer implantation sites (Usta, et al., 2005).

PLACENTA ABRUPTIO

Placenta abruptio is the condition of premature

separation of the placenta from the uterus. This causes

painful bleeding during the third trimester. For each year

of smoking the risk of abruption increases by 40 percent

and 25 out of 100 cases of abruptio are linked to smoking

(Usta, et al., 2005).

GROWTH RESTRICTION AND SGA

As discussed earlier, fetal hypoxia can lead to IUGR.

The average birth weight of a term baby is 2500 grams. A

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baby that has been exposed to cigarettes weighs an average

of 90-200g lighter at term than babies who are not exposed.

Pringle, et al shows that weight, length and head

circumference were all decreased at birth in babies exposed

to smoking in utero compared to non-exposed babies.

Ultrasound found no significant reduction in head,

abdominal circumference or fetal length at 20 weeks

gestation; however, the changes were noted at 30 weeks

gestation and were still evident at birth. They also found

that insulin-like growth factor was significantly lower in

cord plasma of babies exposed to smoke. The placental

weight was also reduced in the babies. This reduction was

dose dependant; mothers who smoked 20 cigarettes daily had

placentas that were 400 grams lighter than mothers who did

not smoke (Pringle, et al., 2005).

ECTOPIC PREGNANCY

Ectopic pregnancies are the primary cause of death in

the first trimester of pregnancy to the mother. Common

causes of ectopic pregnancies are pelvic inflammatory

disease, tubal surgeries and a history of infertility.

However, with the increase in the number of women who

smoke, there have also been increases in the number of

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ectopic pregnancies. As discussed earlier the components of

cigarettes have many negative effects.

These toxins also have an effect on tubal motility as

discussed by Handler, Davis, Ferre and Yero. They measured

wave amplitude of tubal contractions before and after

smoking and found that nicotine exposure caused decreased

uterotubal activity and longer periods of inactivity. In

addition to the effects the nicotine has on tubal activity,

the idea that smoking also reduces immunity has brought up

questions about the increase in pelvic inflammatory disease

and the effects it has on tubal infections. Overall it was

found that smoking increases the risk of ectopic

pregnancies twofold compared to nonsmokers and the amount

of risk is dose related (Handler, et al., 1989).

STILLBIRTH AND INFANT MORTALITY

Still birth occurs when a fetus dies in utero or

during labor and is then delivered. The chances of having a

still birth double with nicotine exposure in the womb. The

mechanism of death is most likely due to growth retardation

as a result of hypoxia from excess carbon monoxide in the

blood. Women who stop smoking greatly decrease their

chances of having a still birth and if they can stop

smoking by their 16th week of pregnancy 25 percent of all

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still births could be prevented (American Society for

Reproductive Medicine, 2003).

MATERNAL SMOKING AND THE PEDIATRIC PATIENT

The effects of maternal smoking on the infant can lead

to many abnormalities including low birth weight, cleft

palate, nicotine withdrawal and an increased incidence of

sudden infant death syndrome (SIDS), asthma and attention-

deficit/hyperactivity disorder (ADHD). Many of these

problems occur due to the chemistry of nicotine and how it

affects the vasculature in utero and the effects it has on

the development of the lungs and neurotransmitters in the

brain.

MATERNAL SMOKINGAND LOW BIRTH WEIGHT

Smoking during pregnancy can double a womens risk of

having a baby at low birth weight and 12 percent of babies

born to smokers were of low weight (less than 2500 grams).

As discussed earlier maternal smoking during pregnancy can

cause intrauterine growth restriction which can lead to

lower birth weights in the newborn. Low birth weight

infants account for 7.6 percent of all live births and most

of these are caused by smoking. Many of these infants will

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die since approximately 69 percent of all infant deaths are

due to low birth weight (Law, 2003).

Nicotine causes vasoconstriction of the arteries in

the body which leads to decreased flow and is the major

cause of myocardial infarction and cerebral vascular

accidents in the United States. Low birth weight is caused

by the same pathology. There is a decreased amount of

oxygenated blood going to the placenta due to the

vasoconstriction of the arteries when the mother smokes

which leads to poorer nutrition and inability to grow in

utero. These infants do no develop fully, having increased

risks for future problems including sudden infant death

syndrome and asthma.

RISK OF CLEFT LIP AND PALATE DEFORMITY

Cleft lip and palate are the fourth most common birth

defects in the world and account for 1 of every 700

newborns. During fetal development the palate is normally

formed during the fourth to seventh weeks of gestation with

fusion occurring at the ninth week of gestation. When this

closure fails, a cleft palate or lip results. This is

characterized by an incomplete fusion of the lip or hard

palate which disables the infant in their ability to

breathe and eat. If left uncontrolled, long term speech and

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hearing loss can occur. Cleft palate babies will require

approximately 10 to 20 surgeries throughout their lives to

have full function of their mouths; even then they will

still have scarring and most likely be left with a speech

impediment (Chung, 2000).

Studies have shown that the more cigarettes the mother

smokes the higher the risk for cleft palate deformity,

again the dose-dependent theory. The thought is behind how

the chemicals in the cigarettes alter the transforming

growth factor-alpha gene variants. Transforming growth

factors are important because they play crucial roles in

the development of embryonic tissues, epithelial cells,

tissue regeneration and regulation of the immune system.

When the chemicals of the cigarettes alter the transforming

growth factors, it delays or inhibits the growth of the

embryonic tissues in utero and leads to malformations of

the infant (Shaw, 1996).

NICOTINE WITHDRAWAL IN THE NEWBORN

A mother who smokes during pregnancy has many things

to worry about with her child; however, nicotine withdrawal

most likely is not one of them. Just as in cocaine, heroin

and alcohol use during pregnancy the fetus builds up an

addiction to these chemicals. When the chemicals are

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suddenly taken away the infant starts to crave them and

go through withdrawal. Some of the withdrawal symptoms the

infant will encounter are insomnia, headache, stomach pain,

constipation and gas. These can all lead to a very unhappy

and inconsolable infant.

When it comes to the heavier drugs more severe forms

of withdrawal proceed, as in seizures and electrolyte

abnormalities. When an infant becomes addicted to nicotine

the results are similar for why it is so hard for people to

quit smoking. The number of nicotinic receptors in the

brain are increased immensely which leads for more and more

of them requiring nicotine to stay calm. When they do not

receive the nicotine, the infant becomes more agitated and

excitable.

When mothers smoke the chemicals cross the placenta

and act as vasoconstrictors reducing uterine blood flow by

up to 38%. This results in fetal hypoxia and brain and

neuronal damage (Law, 2003). This is also the cause of the

infant having a higher risk of attention-

deficit/hyperactivity disorder, which is discussed later.

SUDDEN INFANT DEATH SYNDROME

Sudden infant death syndrome, or SIDS, is defined as

death of an infant unexplainable by postmortem exam. SIDS

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is fairly common, being two of every 1000 children born in

the United States. This commonly occurs in children under 6

months of age, more commonly between the hours of 4AM-6AM

and is the most commonly unexplained cause of death before

the age of one (Auth, 2006).

The actual cause of SIDS is unknown; however, there

are many hypothesized reasons with the main one being the

inability to wake oneself when hypoxia occurs. When infants

feel they are out of oxygen and stop breathing, receptors

in the brain trigger what is called autoresuscitation.

When this fails the infant is unable to awaken and take a

breath. One of the major risk factors for impaired

autoresuscitation is the effects of nicotine and how it

raises the arousal threshold in the infant so they are

unable to wake up, turn their head and gasp for air. This

risk is greatly increased with second hand smoke continued

in the home after nicotine exposure in utero (Thompson,

2006).

Other risks factors of SIDS include sleeping in the

prone position, low birth weight, low socioeconomic status,

drug-addicted mothers and family history of SIDS. Even with

these other risk factors smoking cessation while pregnant

and after birth, studies have shown a great decrease in the

incidence of SIDS.

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SMOKING AS A CAUSE OF ASTHMA IN THE PEDIATRIC PATIENT

Asthma is a major cause of hospital emergency room

visits in the young patient. Asthma is a reversible type

lung disease that is caused by a triad of obstruction,

hypersensitivity of airways and inflammation. There is

initially inflammation of the smooth muscle layer of the

trachea, then large amounts of mucus are secreted in

response to some allergen and as the eosinophils and

lymphocytes travel to the area, a greater amount of

obstruction occurs leading to an asthma attack.

It is well known that secondary cigarette smoking

leads to acute asthma attacks because of bronchial

irritation and inflammation. Asthma can be caused by other

triggers such as household allergens, pollen, mold, mildew,

extreme temperatures and pet dander. However, recent

studies have shown that mothers who smoke during pregnancy

cause a higher risk for their child to acquire asthma

usually within the first 3 years of life. It was found that

Children with any in utero exposure to maternal smoking

were at increased risk of asthma (Li, 2005).

Many of these children that are exposed to tobacco in

utero are also exposed in their homes after birth; however,

one study has proven that the risk of in utero tobacco

exposure and environmental exposure are independent

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variables in the cause of asthma and both are of equal

risks in causing asthma. As explained in the American

Journal of Respiratory and Critical Care Medicine, smoking

during pregnancy causes many dangerous carcinogens to cross

the placenta and harm the development of the lungs

(Gilliland, 2001). The lungs start to develop around 6-8

weeks gestation and in a healthy full-term fetus are

completed before birth. This means at the critical

developmental times, if the mother is smoking the ability

for the lungs to mature correctly is hindered. This leads

to lower surfactant levels which decreases the ability of

the lungs to expand and contract. The alteration of

development leads to lower lung function in general and

increased bronchial hyperactivity (Gilliland, 2001).

The factors that cause asthma are bronchial

irritation, inflammation, and spasm. It makes sense that

over activity of the smooth muscles due to the chemical

exposure from smoking is a high risk factor for asthma.

Therefore, tobacco smoke is not only a trigger for an

asthma attack it is also linked with the cause of asthma.

In the research it is estimated that if mothers did not

smoke while pregnant there would be an overall reduction in

asthma by approximately 15 percent (Gilliland, 2001).

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ATTENTION-DEFICIT/HYPERACTIVITY DISORDER AND SMOKING

Attention-deficit/hyperactivity disorder, or ADHD, is

on the rise in the United States. ADHD is defined as a

pattern of behavior where the child is inattentive or

hyperactive, but most commonly a mix of the two.

Inattentive type features short attention span, inability

to listen or follow instruction, forgetfulness, inability

to organize and easily distracted. Hyperactive type is

classified as being fidgety, difficulty staying seated or

waiting in line, impulsive speech and inability to remain

quiet. There must be six of the above symptoms for

classification and they must last at least 6 months with

the diagnosis before 7 years old (Auth, 2006).

There are many speculations of what is causing this

disorder in children, as in parental neglect, lack of

discipline and other environmental factors. One theory is

that mothers who smoke while pregnant increase the risk of

ADHD. Studies have shown that there is a threefold

increased risk for having offspring with hyperkinetic

disorder with mothers who smoked while pregnant compared

with those who did not (Schmitz, 2006). The physiology

behind these facts is that nicotine reduces cerebral blood

flow to the brain which leads to a low birth weight,

microcephaly and abnormalities in the neuronal matter of

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the body and result in lower IQs. This in turn is expressed

as a hyperactive child that is unable to pay attention in

class and mentally does not have the capability of higher

level thinking. These children also have a higher number of

nicotinic receptors in the brain, as do adults who smoke

and are much more easily agitated than a child not exposed

to nicotine in utero (Schmitz, 2006).

SMOKING CESSATION IN THE PREGNANT PATIENT

As discussed in this paper there is a high importance

in smoking cessation of the pregnant patient. This needs to

be a goal set as early as possible in the pregnancy or when

planning a pregnancy. The first process as with all other

smokers who are trying to quit; the 5 As which are Ask,

Advise, Assess, Assist, and Arrange. First ask about

thoughts of smoking cessation, advise on the long-term

effects to the infant and mother, assess the willingness to

quit, assist the mother in quitting and arrange for a stop

date and other help that may be necessary.

However, the help that we can actually give other than

emotional support and counseling to the pregnant mother may

be greatly limited. Studies have not shown whether the risk

or benefit is higher in using nicotine replacement in the

pregnant patient. The American College of Obstetricians and

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Gynecologists, ACOG, recommends that nicotine patches and

gum should only been used in the pregnant patient when

counseling has failed and nicotine nasal spray and inhaler

should be avoided since it is a Category D and may cause

harm to the developing fetus. Bupropion should again only

be used if counseling has failed; this is a Category B drug

and has not been shown to cause actual harm to a human

fetus (Bailey, 2002). With these limited techniques in

smoking cessation of the pregnant patient strong, early

counseling is the first line therapy.

CONCLUSION

Smoking during pregnancy has multiple consequences on the

outcome of the child. From time of conception to early

childhood, the chemicals found in cigarettes play an

integral part in the development and well-being of fetus

and child. Multiple studies have consistently shown that

cigarettes cause complicated pregnancies which include

infertility, placenta previa and abruption, spontaneous

abortion, fetal malformations and later can lead to

fetal/infant deaths, developmental delays and childhood

asthma. In many cases smoking cessation before conception

or in early gestation will avoid many of the harmful

effects discussed in this paper.

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REFERENCES

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sheet; Smoking and Infertility.

Augood, C., Duckitt, K., Templeton, A.A. 1998. Smoking and female

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Reproduction. 13(6) 1532-1539.Auth, P.C., Kerstein, M.D. 2006. Physician Assistant review.

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Bailey, D., Taylor, P., Zaichkin, J. 2002. Smoking cessation

during pregnancy: Guidelines for intervention. Washington

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Centers for Disease Control. 2007. Smoking and pregnancy.

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Chung, K.C., Kowalski, C.P., Kim, H.M., Buchman, S.R. 2000.

Maternal cigarette smoking during pregnancy and the risk of

having a child with cleft lip/palate. Plastic &Reconstructive Surgery. 105 (2) 485-491.

Gilliland, F.D., Li, Y., Peters, J.M. 2001. Effects of maternal

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asthma and wheezing in children. American Journal of

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Baumann, P. 2005. Smoking in pregnancy revisited: Findings

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Handler, A., Davis, F., Ferre, C., Yeko, T. 1989. The

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Thompson, J. M., Thach, B.T., Becroft, D.M., Mitchell, E.A. 2006.

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Schmitz, M., Denardin, D., Silva, T.L., Pianca, T., Hutz, M.H.,

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