A. Spinillo et al., SOCIODEMOGRAPHIC AND CLINICAL-VARIABLES MODIFYING THE SMOKING-RELATEDRISK OF LOW-BIRTH-WEIGHT, International journal of gynaecology and obstetrics, 51(1), 1995, pp. 15-23
Objective: The purpose of the study was to evaluate the sociodemograph
ic and clinical variables modifying the smoking-related risk of low bi
rth weight (<2500 g). Method: This case-control study included a popul
ation of 967 singleton low birth weight deliveries and 967 selected co
ntrols. Unconditional logistic regression analysis was used to test st
atistical significance of the interactions between smoking in pregnanc
y and other risk factors for low birth weight. Results: Increasing mat
ernal age and parity potentiate the smoking-related risk of a low birt
h weight infant. The effect of maternal smoking on the risk of low bir
th weight was significantly increased in patients with a history of pr
evious spontaneous abortion (excess risk 2.30, 95% C,I, 1.24-4.27) and
in patients of high compared with patients of intermediate or low soc
ial class (excess risk 1.97, 95% C.I, 1.1-3.57). Smokers with less tha
n two prenatal visits per trimester were at significantly greater risk
of delivering a low birth weight infant (excess risk 2.36, 95% C.I. 1
.14-4.87) than their counterparts with more frequent prenatal visits.
Among clinical variables, the effect of maternal smoking on the risk o
f low birth weight was significantly increased in women with a history
of first trimester hemorrhage during the current pregnancy (excess ri
sk 2.67, 95% C,I, 1.30-5.49). Conclusions: The smoking-related risk of
low birth weight is very high in some subgroups of women. Identificat
ion of these subgroups could be important for prenatal counseling.