Structured Abstract
Smoking and Pregnancy
Prepared by Susan E. Moner, MD, Spaulding Rehabilitation Hospital, Boston,
Mass.
These recommendations were finalized by the Task Force in June 1993
Contents
Objective
To make recommendations on interventions that will reduce or stop smoking
in pregnant women in Canada.
Burden
of Suffering
Aside from increasing morbidity and mortality from cancers, cardiovascular
and pulmonary disease in the mother, smoking has been implicated in the
etiology of abruptio placenta, placenta previa, spontaneous abortion, premature
delivery, and stillbirth. Retarded fetal growth in the offspring
of smokers may be attributable to several factors, including the vasoconstricting
properties of nicotine, elevated fetal carboxyhemoglobin and catecholamine
levels, fetal tissue hypoxia, reduced delivery of nutritional elements
and elevation of heart rate and blood pressure. Retarded fetal growth
(about 18% of cases are caused by prenatal smoking) is a significant public
health concern because low birth weight is the most important single determinant
of neonatal and infant morbidity and mortality.
Options
Options include smoking cessation advice given by a physician or midwife
and supplemented by print information, feedback of laboratory values,
group counselling, and multicomponent programs. Nicotine replacement therapy
is not considered.
Outcomes
For the fetus, outcomes include intrauterine growth retardation, and shortened
gestation. For the infant, outcomes include low birth weight, respiratory
distress syndrome, sudden death syndrome, decreased physical growth, other
respiratory disorders such as asthma, and reduced cognitive ability. For
the mother, outcomes were shortened gestations, increased mordibity, other
diseases and disorders associated with smoking, recidivism, and smoking
cessation. Costs were assessed.
Evidence
MEDLINE searches were done for the years 1966 to 1993 using the key words
smoking; smoking cessation; tobacco; infant, low birth weight; infant,
small for gestational age; infant, newborn; birth weight; fetal growth
retardation; abnormalities; brain; development; brain growth; psychometrics;
child development; pregnancy; prenatal care; exposure; delayed effects;
longitudinal studies; and evaluation studies. Authors were also searched
in Science Citation Index, experts consulted, files of organizations searched,
and bibliographies of papers reviewed. Study results were synthesized in
table or graphic format only.
Recommendations were graded as:
|
A
|
Good evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
B
|
Fair evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
C
|
Poor evidence regarding inclusion or exclusion of the condition
in a PHE, but recommendations may be made on other grounds. |
|
D
|
Fair evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
|
E
|
Good evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
Quality of evidence was rated according to 5 levels:
|
I
|
Evidence from at least 1 properly randomized controlled
trial (RCT). |
|
II-1
|
Evidence from well-designed controlled trials without randomization. |
|
II-2
|
Evidence from well-designed cohort or case-control analytic
studies, preferably from more than 1 centre or research group. |
|
II-3
|
Evidence from comparisons between times or places with
or without the intervention. Dramatic results in uncontrolled experiments
could also be included here. |
|
III
|
Opinions of respected authorities, based on clinical experience,
descriptive studies or reports of expert committees. |
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993.
Consensus was reached on final recommendations.
Benefits,
Harms, and Costs
25% to 40% of pregnant women stop smoking, at least for a short time, without
intervention. 4 RCTs assessed smoking cessation advice and although design
problems occurred, quit rates through to the end of the pregnancy were
6% to 14% in the intervention group and 1% to 6% in the control groups.
A meta-analysis of 3 trials showed that the odds ratio (OR) for quitting
after advice was 0.39, 95% CI 0.21 to 0.75. Women who had their first child
and received advice to stop smoking had infants who weighed 68 g more than
women who did not receive advice; no differences were found for the weight
of infants of women who were multiparas.
Feedback of laboratory values was assessed in 3 trials and did not significantly
change smoking rates. 4 trials of group counselling were done, with mixed
results: 1 with low compliance and 1 with a strong control intervention
did not show any differences, while 2 studies showed higher abstinence
rates after intervention (14% vs 8% and 15% vs 5%).
6 trials (4 RCTs) showed that quit rates were increased by all behavioural
strategy interventions, birth weighs increased, and fewer low and very
low birth weight babies were born to women who had quit smoking. 1 meta-analysis
found that personal advice supplemented by written materials reduced smoking
during pregnancy (OR 0.30, 95% CI 0.23 to 0.38).
3 studies found smoking cessation interventions were cost effective
when taking into account the cost of the intervention and hospital deliveries.
Most mothers who quit smoking during pregnancy had started again after
3 years (72%) and 91% of those who had not quit during pregnancy were still
smoking.
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.
-
Good evidence exists to include smoking cessation interventions in the
periodic health examination for pregnant women who smoke. The interventions
can be advice, multiple component programs, and/or behavioural strategies.
[A, I, II-2]
Validation
This report was externally peer reviewed. The Canadian Nurses Association
and the 1989 U.S. Preventive Services Task Force recommend that pregnant
women receive smoking cessation education. The Canadian Medical Association,
the American College of Physicians, the American College of Obstetricians
and Gynecologists, and the American Academy of Pediatricians recommend
that physicians encourage smoking cessation. The Royal College of Physicians
and Surgeons of Canada recommend that persons who wish to stop smoking
should receive effective help.
Sponsors
The Canadian Task Force on Preventive Health Care
developed this guideline with funding from Health Canada.
Selected
References
Source Document
Link to Full Text of this
review
Link to Summary Table of Recommendations of this review
Link to Selected References list of this review
Top of Page
CTFPHC
Home Page
Copyright © 1997 Canadian
Task Force on Preventive Health Care
For any technical issues please contact: webmaster@ctfphc.org
Last modified: June 10, 1998.