Smoking Cigarettes and the
Unborn Baby
Question: I attended the birth of a baby to
a mother who smoked the entire pregnancy. During her labor and
delivery, she was administered oxygen, her placenta was in pieces,
and her baby was having breathing difficulties and transferred to
the NICU. While there were other factors such as the use of drugs in
her labor and meconium staining, would the smoking have contributed
greatly to these complications? What other complications in labor
and delivery and in the baby can a smoking mother anticipate? ~anonymous doula~
Susan P. Osborne, DO
In
residency, I had the same experience. We saw a large volume of
deliveries, many from the public health clinic, some with little
prenatal care. We encountered friable, calcified, old-looking
placentas in mothers who were not post term, often they were
preterm. In my home-birth practice, smoking was a relative
contraindicated to home delivery.
The March of Dimes maintains an excellent accessible website at
www.marchofdimes.com. They cite that 20% of women in the US smoke,
and not all quit during pregnancy. This results in an excess of 11%
still births, and 5% more newborn deaths. In the Reuter’s news
article “Prenatal Smoke Exposure Linked with Apnea in Preterm
Infants” from Am J. Respir. Care Med (2004; 169; 733-738) sleep
studies were done on 30 infants – 16 were exposed to prenatal smoke,
14 were not. The smoke exposed infants showed 28.6 apneic
events/hour, compared to 13.2 in the controls. The subjects in the
maternal smoking group had 34.5 arousals per hour, compared to
46.3/hour in the controls. After a respiratory event, 10.7% of the
smoke exposed infants aroused, compared to 29.4% for controls. In an
American Journal of Public Health Article, March 1995 (vol.85, no.3,
pp395-398) patients reporting bias was eliminated in studies by
measuring serum cotinine. In this study, confounding variables of
infant sex, maternal race, parity, age education, weight gain,
maternal alcohol and caffeine consumption showed no correlation to
preterm birth and infant weight – but – serum cotinine was related
on a dose response basis. 0-1.9mg/ml of cotinine were classified as
nonsmokers, 2.0-10.0mg/ml were passive smoke exposed, 0-78mg/ml were
light smokers, 79-165mg/ml were moderate smokers, and >166mg/ml were
heavy smokers. Skeptical moms may see having a smaller baby as
easier to birth not realizing these are not small, healthy babies,
many are preterm due to the placenta wearing out early.
March of Dimes also stated, 12.2% of babies born to smokers were
less than 5˝lbs, compared to 7.5% of nonsmokers. Specific to your
question – twice as many placenta previas and abruptions are seen in
smokers vs. nonsmokers. The studies on this mechanism go back to the
early 1980s – specific histologic studies on the “morphologic change
in the placental villi” in relation to quantity of tobacco exposure
were published by Asmussrin 1980 and VanderVeen, and Fox in 1982.
These were referenced in the paper, “The Effects of Passive Smoking
on the terminal Villi of Human Placenta”, published in the Journal
of the Anatomical Society of India 50(1) 19-23(2001) by Ruth, G,
Jinn, A.K, Bastia, B. Sood, M., and Makherjee, A. One hundred
placentas were studied, all from nonsmokers, but 50% had passive
exposures though husbands chain smoking Beedis. Now, keep in mind
the complex mechanism by which the placenta allows transfer of
nutrients without blood mixing. A thin syncytiotrophoblastic
membrane lies over a cytotrophoblast layer of cells, all on a thin
basement membrane. The endothelial cells of the capillary beds lie
on one side of this structure, and this is repeated in villi over a
vast surface area, projecting into in the myometruim of the uterus.
In 36% of the smoke-exposed placentas, the syncytiotrophoblastic
membrane was bunched up in knots, compared to 24% of the controls.
The number of cells in the trophoblastic layer was 4.27/field in the
controls, but were 70.25 field in the passive smokers. Endothelial
cells intruded into the vascular layer 5.35 times/hpf vs 0.66 times
in the controls. 75% of the passive smoker had irregularly irregular
basement membranes in a zigzag pattern. Absorption of nutrients is
impaired by this irregularity, and you can imagine why the blood
vessels grow in to get more absorption, which increases the
potential for blood mixing and vessel rupture. This is a scary
situation.
In the family practice setting, I have OB doctors taking my prenatal
patients off of nicotine patches because they are note approved by
the ACOG, so the mom often relapses. Doctors who are willing to do a
c-section against a mother’s will are afraid to upset a mother by
telling her to quit smoking. In a 1985 New York Times article,
William G. Cahon, MD published an opinion “abusing children by
smoking”. In a 1975 article “smoking mothers are more likely to have
hyperkinetic (ADHD) children” was published in the Canadian
Psychiatric Association Journal. (vol 20: 183-187, 1975). Children
who met the criteria for ADHD – were born to mothers who average 14
cigarettes/day, children evaluated as “normal” were born to mothers
who averaged 6 cigarettes /day (which would include the nonsmokers).
Carboxyhemoglobin was found in 2x the levels in the fetus as the
mother. (R. Denson, MD, J.L. Nansom, MA, MA, McWalters, RN,
University of Saskatchewan, CA)
So how does this affect our practice? We have to start very early.
The first pap smear is a chance to screen. I hear “I’ll quit when I
have a baby”, and grandmothers say “I smoked when I had you, and you
turned out okay”. I went to a presentation of a paper at the
American Society of Addiction Medicine on neonatal tobacco
addiction. It was an elegant study. It explained why I see children
who smoke their first cigarette and get high – no nausea, no choking
– they are relapsing after being addicted in the womb. Even care
providers are not immune to this addiction. I am very worried about
this pervasive legal toxin we expose our babies to. Is it all about
freedom? As mothers, we lose some of our freedom when we accept the
responsibility of a child.
Sincerely,
Susan P. Osborne, DO
Dr. Osborne has a Family Practice in Floyd, VA.
She provides prenatal care and midwifery support. She attended
home births in the Richmond area until the Virginia Board of
Medicine placed her license on probation for four years for "aiding
and abetting the practice of midwifery". She is very
homebirth, breastfeeding and mommy/baby friendly and has a
tremendous wealth of experience along with her knowledge. Her
heart exceeds the size of this world! She, along with being a Family
Practice Doc, is the only Medical Examiner for Floyd County, so her
time is preciously filled. We thank her for sharing her time and
knowledge on this important topic. She has indeed helped many folks
take that step to quit smoking. I have very personally
witnessed her educational abilities, in this, and in other areas as
well. ~Susan Oshel~
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