Is maternal smoking during early pregnancy a risk factor for all low birth weight infants?
BACKGROUND
Low birth weight (LBW) infants do not form a homogeneous group; LBW can be caused by prematurity or poor fetal growth manifesting as small for gestational age (SGA) infants or intrauterine growth retardation. We aimed to clarify the relationship of maternal smoking with both SGA and preterm LBW infants.


METHODS
The study population comprised pregnant women who registered at the Koshu City between January 1, 1995, and December 31, 2000, and their children. We performed multivariate analyses using multiple logistic regression models to clarify the relationship of maternal smoking during pregnancy with the SGA outcome and preterm birth in LBW infants.


RESULTS
In this study period, 1,329 pregnant women responded to questionnaires, and infant data were collected from 1,100 mothers (follow-up rate: 82.8%). The number of LBW infants was 81 (7.4%). In this cohort, maternal smoking during early pregnancy was associated with LBW and the SGA outcome. Maternal smoking during early pregnancy was a risk factor for LBW with SGA outcome and for LBW with full-term birth. However, it was not a risk factor for LBW with appropriate weight for gestational age (AGA) and LBW with preterm birth.


CONCLUSIONS
These results suggested that LBW with AGA and LBW with preterm birth were associated with other risk factors that were not considered in this study, such as periodontal disease. For the prevention of LBW, not only abstinence from smoking during pregnancy but also other methods such as establishing a clinical setting should be adopted.
Suzuki
Kohta
K
Department of Health Sciences, School of Medicine, University of Yamanashi, Japan.
Tanaka
Taichiro
T
Kondo
Naoki
N
Minai
Junko
J
Sato
Miri
M
Yamagata
Zentaro
Z
D000328:Adult; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000453:epidemiology; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007236:Infant, Small for Gestational Age; D007564:Japan / Q000453:epidemiology; D015999:Multivariate Analysis; D011247:Pregnancy; D011248:Pregnancy Complications; D011261:Pregnancy Trimester, First; D047928:Premature Birth / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D012424:Rural Population; D012907:Smoking / Q000009:adverse effects*; D011795:Surveys and Questionnaires