European Journal of Pediatrics · 9 authors, 3 centres
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This meta-analysis of 15 prospective cohort studies (N=73,448) found that maternal smoking during pregnancy is associated with a small but statistically significant increase in systolic blood pressure (SBP) of offspring during childhood and adolescence (β=0.31 mmHg; 95% CI: 0.14–0.49). No significant association was found for diastolic blood pressure (DBP). The overall quality of evidence was rated low for SBP and very low for DBP, limiting clinical inferences.
**Background:** High blood pressure in children is increasingly common, with a global prevalence of approximately 4.0% in those aged 6–19 years. Maternal smoking during pregnancy is known to cause placental changes and fetal alterations, but its precise role in childhood hypertension remains controversial. This systematic review with meta-analysis aimed to evaluate the association between maternal smoking during pregnancy and offspring's blood pressure during childhood or adolescence, focusing exclusively on prospective cohort studies.
**Methods:** The review followed PRISMA guidelines and was registered in PROSPERO (CRD42021247824). A bibliographic search of MEDLINE (PubMed), EMBASE, and CENTRAL databases was conducted in March 2022. Eligible studies were prospective cohort studies evaluating the association between maternal smoking in pregnancy and offspring blood pressure at ages 3–17 years, providing adjusted mean differences with 95% confidence intervals. Fifteen studies met inclusion criteria for the meta-analysis (N=73,448 for SBP; N=31,459 for DBP). Quality was assessed using a modified Newcastle-Ottawa scale, and evidence levels were rated using GRADE. A random effects model was applied, with heterogeneity evaluated using Cochrane's Q test and I² statistic.
**Key Results:** Maternal smoking during pregnancy significantly increased offspring SBP (β=0.31 mmHg; 95% CI: 0.14–0.49). Inter-study heterogeneity was not substantial (I²=0.00%). No significant association was found for DBP (β=−0.16 mmHg; 95% CI: −0.75–0.43), with high heterogeneity (I²=73.10%). Subgroup analyses showed greater SBP increases in studies with recruitment before 1990 (β=0.87 mmHg; 95% CI: 0.28–1.47), non-European studies (β=0.67 mmHg; 95% CI: 0.25–1.09), studies using manual sphygmomanometry (β=0.81 mmHg; 95% CI: 0.15–1.47), and studies adjusting for birth weight (β=0.69 mmHg; 95% CI: 0.06–1.32). Egger's test suggested possible publication bias for SBP (p<0.1). The GRADE level of evidence was low for SBP and very low for DBP.
**Clinical Implications:** This study supports the hypothesis that maternal smoking during pregnancy may increase offspring SBP during childhood and adolescence, though the effect size is small (<1 mmHg). The low quality of evidence precludes strong clinical inferences. The association with SBP but not DBP may reflect effects on arterial stiffness rather than peripheral vascular resistance. Future research should use biomarkers (e.g., cotinine) for exposure assessment, examine dose-response relationships, and adjust for key confounders including postnatal environmental tobacco smoke exposure.