Background: Maternal smoking during pregnancy is a major cause of intrauterine growth restriction and childhood obesity, but only a few studies have examined the association of smoking cessation before and during pregnancy with fetal and childhood growth. We examined this association in a prospective cohort study in Japan.
Methods: Our study included children born between 1991 and 2006 and their mothers. Using a questionnaire, maternal smoking status was recorded at pregnancy. The anthropometric data of the children were collected during a medical check-up at age 3 years. Multiple linear and logistic regression models were used for data analysis stratified by sex.
Results: In total, 2663 mothers reported their smoking status during early pregnancy, and data were collected from 2230 (83.7%) children at age 3 years. Maternal smoking during pregnancy was associated with a significant reduction in birth weight (approximately 120-150 g). Body mass index at age 3 years was significantly higher among boys born to smoking mothers than among boys born to nonsmoking mothers. Maternal smoking during pregnancy was associated with overweight at age 3 years among boys (adjusted odds ratio, 2.4; 95% CI, 1.03-5.4). However, among women who stopped smoking in early pregnancy, there was no increase in the risks of a small for gestational age birth or childhood overweight at age 3 years.
Conclusions: Children born to mothers who stopped smoking before or during early pregnancy had appropriate fetal and childhood growth.
背景：: 妊娠中の喫煙は子宮内胎児発育遅延や子どもの肥満の主要なリスクファクターであるが、妊娠前後の禁煙が胎児あるいは子どもの発育に与える影響の検討は少ない。そこで、日本における前向きコホート研究のデータを用いて、妊娠前後の禁煙の影響を検討した。
方法：: 対象者は1991年から2006年までに出生した児とその母親である。妊娠前後の母親の喫煙状況は妊娠届出時に質問紙で、身体測定のデータは3歳児健診時に収集された。重回帰分析と多重ロジスティックモデルにより、男女別に妊娠前後の喫煙状況が胎児および児の発育に与える影響を検討した。
結果：: 妊娠初期の喫煙状況について2663人の母親が回答し、そのうち2230人（83.7%）について3歳児健診時のデータが収集された。妊娠中の喫煙は出生体重を120－150g減少させた。また男児では、3歳時のBody Mass Indexは妊娠中に喫煙していた母親で、喫煙していなかった母親より有意に大きかった。妊娠中の喫煙は3歳時の過体重についても男児で有意なリスクとなっていた（調整後オッズ比2.4、95%信頼区間1.03－5.4）。しかしながら、妊娠初期に禁煙した母親については、胎内発育を抑制したり3歳時での過体重となったりするリスクを増大することはなかった。
結論：: 妊娠前後の禁煙は、適正な胎児および子どもの発育につながる可能性が示唆された。