Association between the number of live births and hazard of
all-cause premature mortality stratied by potential risk factors
We also conducted stratified analyses according to the potential risk
factors including age (born year), race, BMI, Townsend deprivation
index, smoking status, moderate drinking, diabetes, hypertension,
asthma, emphysema and chronic bronchitis in Supplementary Table 2. The
association of parity with hazard of all-cause premature mortality
appeared was not significant in Other ethnic group participants (P-trend
= 0.447), where the protective effect of mothers with double children on
all-cause premature death had disappeared (HR2=1.02,
95% CI: 0.31-3.31). We also found the harmful effects of the
nulliparous women on all-cause premature death had become not
significant in obese participants (BMI≥ 30 kg/m2)
(HR0=1.12, 95% CI: 0.99-1.27). Notably, the observed
significant association of the number of live births with hazard of
all-cause premature mortality appeared to be abolished in
current-smokers (P-trend = 0.003) and overdrinker (P-trend = 0.114).
Meanwhile, the chronic diseases such as diabetes, asthma, emphysema and
chronic bronchitis also had an impact on the relationship between parity
and all-cause premature mortality. We did not find significant
interactions between other potential confounders and the number of live
births on hazard of all-cause premature mortality.