Parental smoking during pregnancy and offspring cardio-metabolic risk factors at ages 17 and 32

Highlights

• We examine offspring cardio-metabolic risk in relation to parental smoking during pregnancy.

• Parental smoking was positively associated with offspring adiposity at ages 17 and 32.

• Associations with offspring insulin and lipid levels at age 32 were non-significant.

• Results highlight potential long-term health impact of exposure to parental smoking.

• Efforts to promote smoking cessation of parents before pregnancy may be warranted.

Abstract

Objective

To examine the association of maternal and/or paternal smoking during pregnancy with offspring cardio-metabolic risk (CMR) factors at adolescence and early adulthood, taking into account socio-demographic, medical and lifestyle characteristics of parents and offspring, as well as offspring common genetic variation.

Methods

We used a population-based cohort of all 17 003 births in Jerusalem during 1974–76, with available archival data on parental and birth characteristics. Measurements at age 17 were assessed at military induction examinations for 11 530 offspring. 1440 offspring from the original 1974–1976 birth cohort were sampled using a stratified sampling approach, and were interviewed and examined at age 32. Parental smoking during pregnancy (i.e. maternal, paternal and any parent) was primarily defined dichotomously (any number of cigarettes smoked daily by mother or father during pregnancy vs. non-smokers). Additionally, smoking was assessed by quantity of cigarettes smoked daily. Linear regression models were used to evaluate the associations of parental smoking during pregnancy with various offspring CMR factors, after controlling for potential confounders and for genetic variation in candidate genes.

Results

Prevalence of exposure to parental smoking in-utero (i.e. smoking of any parent) was 53.2% and 48.4% among the 17 years old and 32 years old samples, respectively. At age 17, smoking of at least one parent during pregnancy was significantly associated with weight (B = 1.39), height (B = 0.59), BMI (B = 0.32) and pulse rate (B = −0.78) (p-values < 0.001). At age 32, parental smoking, adjusted for covariates, was associated with 2.22 kg higher mean offspring weight, 0.95 cm higher mean offspring height, 0.57 kg/m² higher BMI, and 1.46 cm higher waist-circumference (p-values ≤ 0.02). Similar results, reflecting a dose response, were observed when maternal and paternal smokings were assessed by number of cigarettes smoked daily.

Conclusions

This prospective study demonstrates a potential long-term adverse effect of parental smoking during pregnancy on offspring health and calls for increasing efforts to promote smoking cessation of both parents before pregnancy.

Introduction

Active and passive cigarette smoking are major risk factors for multiple clinical conditions, such as cardiovascular disease, cancer, chronic lung disease, and mortality [1], [2]. Hence, cigarette smoking is a major public health concern globally. Despite the known harmful effects of cigarette smoking on the health of mothers and their children, it is estimated that 22 to 34 percent of American women of reproductive age smoke cigarettes [3]. Smoking during pregnancy is one of the most important modifiable risk factors associated with adverse pregnancy outcomes. The negative impact of cigarette smoking on fetal health is well established and cigarette smoking has been associated with numerous adverse perinatal outcomes [4], [5]. Low birth weight (LBW) (<2500 g) is the best-studied complication of smoking during pregnancy. Women who smoke are 1.5–3.5 times more likely to have a LBW infant with increasing risk as cigarette consumption increases [6]. It has been estimated that at least 20% percent of LBW and small for gestational age infants are attributed to tobacco exposure during pregnancy [7]. Exposure to passive smoking during pregnancy also appears to have adverse effects on the fetus, child, and adult offspring [8], [9], including increased rate of stillbirth, and reduced mean birth weight [9].

Additionally, parental smoking during pregnancy is associated with long-term offspring health risks. Associations of parental smoking with offspring cardiovascular risk factors have been demonstrated mostly in pre-pubertal children [10], [11]. Only few studies have examined these associations in adolescents and adults and most of them were retrospective [12], [13], [14], [15]. Prior studies have focused mostly on maternal smoking, rather than paternal smoking, and the associations of maternal smoking with offspring obesity [16], [17] and blood pressure [18]. Evidence regarding the associations of parental smoking with other cardio-metabolic risk (CMR) traits is sparse [19], [20], [21].

It has been suggested that the long-term effects of both paternal and maternal smoking on offspring health are related to effects on the intrauterine environment as well as to postnatal characteristics that are associated with CMR [22], [23], [24].

In our study, we aimed to assess the effect of maternal and/or paternal smoking during pregnancy on a range of cardio-metabolic risk factors at age 17 and 32, taking into account various socio-demographic, medical and lifestyle characteristics of the parents and the offspring, as well as common genetic variation in offspring.