Parity, Age at First Birth, and Risk of Death from Non-Hodgkin’s Lymphoma: A Population-Based Cohort Study in Taiwan

Abstract

We undertook this study to examine whether there exists an association between parity and age at first birth and risk of death from non-Hodgkin’s lymphoma (NHL). Our sample included a total of 1,292,462 women who had a first and singleton childbirth between 1 January 1978 and 31 December 1987. We followed each subject from their first childbirth to 31 December 2009, and determined their vital status by merging natality data with Taiwan’s national death certificate database. Hazard ratios (HR) of death from NHL associated with parity and age at first birth were estimated using Cox proportional hazard regression models. In all, 412 NHL deaths were recorded during 34,980,246 person-years of follow-up. NHL mortality rate was 1.18 cases per 100,000 person-years. Older age at first birth (>23 vs. ≤23 years) was linked to an increased risk of death from NHL (adjusted HR = 1.41; 95% CI = 1.13–1.75). Controlling for age at first birth, the adjusted HR were 0.74 (95% CI = 0.55–0.98) for women with 2 births, and 0.71 (95% CI = 0.53–0.95) for women with 3 births or more, respectively, when compared with women with only 1 birth. A statistically significant downward trend in the adjusted HR for NHL death was detected with increasing parity (p for trend = 0.05). The HR of death from NHL was decreased by 7% (HR = 0.93; 95% CI = 0.87–0.99) for each additional parity. Our findings are consistent with reproductive factors (parity and early age at first birth) conferring a protective effect against the risk of NHL death.

Number of parity and the risk of non-Hodgkin lymphomas: a dose–response meta-analysis of observational studies

“…For example, in the California Teachers Study cohort, a 30% decreased risk of B-cell NHL associated with full-term pregnancies has been observed [8]. Similarly, a population-based cohort study in Taiwan has also found a protective role for each additional parity [9]. In contrast, though, data from the NIH-AARP Diet and Health Study Cohort have indicated null associations between NHL and parity in women [10].…”

Female reproductive factors and risk of lymphoid neoplasm: The Japan Public Health Center‐based Prospective Study

“…With regard to the timing of pregnancy, 1 cohort study with 2 million women found a reduced risk of NHL with delayed age at first birth, 12 whereas 2 case-control studies reported that early age at first birth was associated with a significantly reduced risk of NHL 11,38 or null results [13][14][15][16] The results should, therefore, be considered inconclusive, and age at first birth may not be attributable to the risk of lymphomagenesis.…”

“…2,3 Although attention has focused on pregnancy as a protective factor against the risk of non-Hodgkin lymphoma (NHL) owing to its dramatic alternations in female sex hormones and immune response, a recent systematic review and a meta-analysis suggested only a weak or null association. 3,9 Associations between the risk of NHL and late age at first birth were positive 10,11 or negative, 12 but most studies and a pooled analysis reported a null association. [13][14][15][16] Hormones released during lactation or missed ovulations due to breastfeeding were suggested as a possible mediator of lymphomagenesis, but evidence to determine the effect of breastfeeding is scarce.…”

U-shaped association between fertility and mortality in a community-based sample of Japanese women

“…Tamakoshi et al 5 reported that in a Japanese population, compared with women with two children, all-cause mortality was higher in women with no, one, or five or more children, but they did not report an association between parity and cause-specific mortality. There are a series of studies of parous women in Taiwan that examined the association between parity and specific causes of death such as subarachnoid haemorrhage,15 non-Hodgkin’s lymphoma,16 bladder cancer,17 gallbladder cancer,18 kidney cancer19 and chronic renal failure 20. These studies from Taiwan reported no significant association between fertility and bladder cancer17 or kidney cancer19 but observed increased risks of mortality due to gallbladder cancer18 and non-Hodgkin’s lymphoma16 in women with higher parity compared with that in women with only one child.…”

“…There are a series of studies of parous women in Taiwan that examined the association between parity and specific causes of death such as subarachnoid haemorrhage,15 non-Hodgkin’s lymphoma,16 bladder cancer,17 gallbladder cancer,18 kidney cancer19 and chronic renal failure 20. These studies from Taiwan reported no significant association between fertility and bladder cancer17 or kidney cancer19 but observed increased risks of mortality due to gallbladder cancer18 and non-Hodgkin’s lymphoma16 in women with higher parity compared with that in women with only one child. However, higher parity was associated with lower risks of mortality from chronic renal failure20 and subarachnoid haemorrhage15 in the Taiwanese sample.…”