妊娠が判明してからの禁煙も遅くない

3/26/2009発表　BMJより

妊娠１５週までに禁煙した場合、早産とSGAの発生頻度にに関しては非喫煙妊婦のものと同等まで戻る。
そうでない場合はリスクは高い　早産(4% vs. 10%, RR 2.5, NNH 16.7)　SGA(10% vs. 17%, RR 1.7, NNH 14.3 ).

喫煙者の１０人に一人が早産、６人に一人がSGA,非喫煙者、禁煙者でも１０人に一人がSGAというのは結構驚きです。日本の場合もう少し少ないかもしれませんが、喫煙はやはり思っている以上にリスクを上げるのですね。

「早くやめればリスクは帳消しにできる」


1. McCowan LME, Dekker GA, Chan E, et al. Spontaneous preterm birth and small for gestational age infants in women who stop smoking early in pregnancy: prospective cohort study. BMJ. March 26, 2009 2009;338(mar26_2):b1081-.

http://www.bmj.com/cgi/content/abstract/338/mar26_2/b1081


2500人の初産婦、南半球、前向きコホート
８０％が非喫煙者
１０％は妊娠１５週（+-１週）前に禁煙
１０％継続喫煙

結果は上記の通り

禁煙をした妊婦について、ストレス、不安、うつの増加もなく、

「吸わないとストレスなんです」という言い訳は無用とのこと。

ただし、baseline　characteristicsのに多くの項目おいて、３群に差があり、交絡因子の存在は注意。

Objectives To compare pregnancy outcomes between women who stopped smoking in early pregnancy and those who either did not smoke in pregnancy or continued to smoke. Design Prospective cohort study. Setting Auckland, New Zealand and Adelaide, Australia. Participants 2504 nulliparous women participating in the Screening for Pregnancy Endpoints (SCOPE) study grouped by maternal smoking status at 15 ({+/-}1) week's gestation. Main outcome measures Spontaneous preterm birth and small for gestational age infants (birth weight <10th customised centile). We compared odds of these outcomes between stopped smokers and non-smokers, and between current smokers and stopped smokers, using logistic regression, adjusting for demographic and clinical risk factors. Results 80% (n=1992) of women were non-smokers, 10% (n=261) had stopped smoking, and 10% (n=251) were current smokers. We noted no differences in rates of spontaneous preterm birth (4%, n=88 v 4%, n=10; adjusted odds ratio 1.03, 95% confidence interval l0.49 to 2.18; P=0.66) or small for gestational age infants (10%, n=195 v 10%, n=27; 1.06, 0.67 to 1.68; P=0.8) between non-smokers and stopped smokers. Current smokers had higher rates of spontaneous preterm birth (10%, n=25 v 4%, n=10; 3.21, 1.42 to 7.23; P=0.006) and small for gestational age infants (17%, n=42 v 10%, n=27; 1.76, 1.03 to 3.02; P=0.03) than stopped smokers. Conclusion In women who stopped smoking before 15 weeks' gestation, rates of spontaneous preterm birth and small for gestational age infants did not differ from those in non-smokers, indicating that these severe adverse effects of smoking may be reversible if smoking is stopped early in pregnancy.

Women who stopped smoking did not have increased stress, anxiety, or depression — which, the authors say, "should reassure" women who fear that quitting could cause them undue stress.

WHAT IS ALREADY KNOWN ON THIS TOPIC

Smoking is the single most modifiable risk factor for
adverse pregnancy outcomes in developed countries

Stopping smoking in pregnancy increases birth weight
and reduces rates of all preterm birth

The gestation by which smoking must stop to reverse
effects of smoking on spontaneous preterm births and
small for gestational age infants is not known

WHAT THIS PAPER ADDS

Stopping smoking early in pregnancy, before 15 weeks’
gestation, results in rates of spontaneous pretermbirths
and small for gestational age infants similar to those in
non-smokers

Women who continue to smoke at 15 weeks’ gestation
are more likely than those who stop smoking to have
spontaneous preterm birth

Pregnant women should be offered support and
interventions to help them stop smoking early in
pregnancy