Association between Maternal Smoking during Pregnancy and Low Birthweight: Effects by Maternal Age

Abstract

BackgroundMaternal smoking during pregnancy has been consistently related to low birthweight. However, older mothers, who are already at risk of giving birth to low birthweight infants, might be even more susceptible to the effects of maternal smoking. Therefore, this study aimed to examine the modified association between maternal smoking and low birthweight by maternal age.MethodsData were obtained from a questionnaire survey of all mothers of children born between 2004 and 2010 in Okinawa, Japan who underwent medical check-ups at age 3 months. Variables assessed were maternal smoking during pregnancy, maternal age, gestational age, parity, birth year, and complications during pregnancy. Stratified analyses were performed using a logistic regression model.ResultsIn total, 92641 participants provided complete information on all variables. Over the 7 years studied, the proportion of mothers smoking during pregnancy decreased from 10.6% to 5.0%, while the prevalence of low birthweight did not change remarkably (around 10%). Maternal smoking was significantly associated with low birthweight in all age groups. The strength of the association increased with maternal age, both in crude and adjusted models.ConclusionsConsistent with previous studies conducted in Western countries, this study demonstrates that maternal age has a modifying effect on the association between maternal smoking and birthweight. This finding suggests that specific education and health care programs for older smoking mothers are important to improve their foetal growth.

Low birth weight of institutional births in Cambodia: Analysis of the Demographic and Health Surveys 2010-2014

“…Other related risk factors are included pre-pregnancy weight, parity, history of prior LBW, gestational weight gain and caloric intake, general morbidity and illnesses, malaria, maternal HIV infection cigarette smoking, alcohol consumption, and history of LBW and prematurity [ 11 , 14 , 24 ]. For example, a study by Zheng et al among 92,641 mothers in Okinawa showed that maternal smoking was significantly associated with LBW in all age groups, while Coutinho et al found that smoking beyond the fourth month of pregnancy was a risk factor for LBW, irrespective of the number of cigarettes smoked per day [ 12 , 25 ]. Mother’s level of hemoglobin, and baby’s birth interval are also associated with LBW [ 11 , 12 ].…”

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“…Second-hand tobacco smoke exposure and indoor air pollution remain two major health problems, especially in developing countries, and the effect of passive smoking and cooking smoke on neonatal birth weight has been debated. Smoking during pregnancy can increase the risk of preterm birth, fetal growth restriction, low birth weight, sudden infant death syndrome, and behavioral problems [ 3 , 4 , 5 , 6 ]. Although multiple substances have been identified in cigarette smoke, carbon monoxide (CO) and nicotine are the two responsible for adverse effects on the developing fetus [ 7 , 8 ].…”

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“…The birth weight increase by 0.01 kg per one year increase in the age of the mother. This finding disagree with a 2016 fining [38]. This is due to the reason that the awareness of mothers will be increased as their age increases due to the repeated exposure which finally makes them to take enough quantity and quality of nutrient necessary for their fetus growth [6].…”