Maternal overweight and obesity might increase risks of adiposity and cardiovascular and metabolic diseases in offspring. We examined associations between maternal overweight and obesity severity and risk of cardiovascular diseases (CVDs) in young offspring.

In this population-based cohort study, we used data from live singleton births recorded in the Swedish Medical Birth Register. We calculated maternal BMI in early pregnancy from self-reported height and weight measurements at the first prenatal visit. We used multivariable Cox proportional hazards regression to estimate adjusted hazard ratios (HRs) and 95% CIs. We calculated the proportion of the associations mediated through known consequences of obesity that also predicted cardiovascular diseases and did family case-control analyses.

We identified 2 230 115 live singleton infants (without congenital malformations) in Sweden registered between Jan 1, 1992, and Dec 31, 2016. Overall, 1741 (0·08%) offspring were diagnosed with a cardiovascular disease between ages 1 and 25 years. Cardiovascular disease rates by maternal BMI categories were 0·57 per 10 000 child-years (BMI 18·5–24·9 kg/m 2; normal weight), 0·61 per 10 000 child-years (25·0–29·9 kg/m 2; overweight), 0·67 per 10 000 child-years (30·0–34·9 kg/m 2; obesity grade I), 1·02 per 10 000 child-years (35·0–39·9 kg/m 2; obesity grade II), and 1·38 per 10 000 child-years (≥40·0 kg/m 2; obesity grade III). Compared with offspring of mothers with normal BMI, HRs of cardiovascular diseases were 1·10 (95% CI 0·97–1·25) for overweight, 1·16 (0·95–1·43) for obesity grade I, 1·84 (1·36–2·49) for obesity grade II, and 2·51 (1·60–3·92) for obesity grade III. Risks of cerebrovascular diseases increased with maternal obesity severity and were partly mediated through asphyxia-related neonatal complications. The sibling-cohort analysis also indicated a positive trend between maternal BMI and cardiovascular disease rates.

Our findings indicate that maternal obesity might be a risk factor for cardiovascular diseases in childhood and early adulthood. These results need to be replicated and possible underlying mechanisms identified.