Women with Caesarean section delivery have a higher risk of subsequent coronary heart disease than women with vaginal delivery
Hui-Bih Yuan; Chun-Jen Huang
Background: This population-based cohort study was conducted to elucidate the impact of Caesarean section (CS) delivery on the future risk of coronary heart disease (CHD) in pregnant women.
Methods: We analyzed data retrieved from the Longitudinal Health Insurance Database 2010, which includes medical claims data and registration files for 1 million enrollees randomly selected from the 2010 Registry for Beneficiaries (n = 23.7 million) of the National Health Insurance program in Taiwan. Subjects with a newly diagnosed CHD after delivery were identified with ICD-9-CM codes between January, 2000 and December, 2012. At least two separate inpatient or outpatient medical record diagnosis of CHD were included in this study to confirm the accuracy of the diagnosis. Multivariate Cox proportional-hazards regression models were performed to estimate the hazard ratios (HRs) and the 95% confidence intervals (CIs). 
Results: A total of 52322 pregnant women were included (CS delivery: n=18153; vaginal delivery: n=34169). During 1 to 13 years of follow-up, the incidence of having subsequent CHD in women with CS delivery was significantly higher than that in women with vaginal delivery (1.4% vs. 0.9%; P<0.001). The between-group differences in age and length of hospital stay as well as the incidences of CHD-related prognostic factors, including diabetes mellitus, chronic hypertension, hyperlipidemia, obesity, chronic obstructive pulmonary disease (a proxy for smoking), and thrombophilia were significantly different (all P<0.05). The between-group differences in the incidences of pregnancy-related complications, including preeclampsia, pregnancy-related hypertension, antepartum haemorrhage, early or threatened labour, and preterm and low birth weight were also statistically significant (all P<0.001). After adjusting for the factors that were significantly different, the CS delivery women showed a significantly higher subsequent risk of CHD (HR = 1.32, 95% CI = 1.11-1.58, P<0.001) than the vaginal delivery women.
Conclusions: Women with CS delivery had an increased risk of a subsequent CHD comparing to those women with vaginal delivery.
	
IRB: 02-X11-025, 25-09-2013, Chiau-Suong Liau